plug reading for jetting...info.

[JOHNDOE83]

The most controversial subject on here is how to properly read a plug, I have some advice and some facts to clear up and help everyone having jett issues and plug reading problems. I donot plug chop, will explain at the end...

The pocelain "IS NOT" the proper way to read a plug....in fact the porcelain is how you determine timing, detonation....AND partly needle position....even Trinity will tell you the porcelain is not the way to tell jetting.

The ground strap "Where your plug sparks to" and "is the base of the threads" determines heat range....and "part" of pilot jet.

The carbon ring, "inside the plugs threaded section" determines your actual jetting...

Determining heat range: Our ATVs dont really apply here being that they are setup for the right plug from the start...but here you go. "The ground strap" this is the piece attatched to the plug threads where the spark hits. If the color on the strap is closer to the end...its to cold...if the color goes almost to the threads on the plug its to hot...you want it in the middle of the strap.

This is only important if you have a crazy built "Highly Modded Motor" NOS...High compression 13:1 or more....custom timing, not 3 or 4 degrees...Alcohol....not even a motor like mine.

The pilot jet slightly affects the gound strap area and the ring around the base of the plug...not really nessesary to check being that you want it a tad rich...like a 42 pilot on a stock carb and a 50 in a 450r carb. If its a nice dark even color and your not poping on decel...your pilot and air fuel screw is fine.

The porcelain: The porcelain shows detonation and timing, also needle position. The "tan color" everyone sees on the porcelain after riding a few hours comes from a proper needle setting only.

If there is deposits on the porcelain "Black or shiny" you have detonation, timing really isnt an issue unless you have that "highly modded motor" stated above...ex's are fine with 3, 4, or 6 degree timing depending on mods.

ACTUALLY DETERMING JETTING: OK, if all the above is ok after riding for a few hours, then you need to do a plug run!

Ride at wide open throttle till fourth or fifth gear, squeeze the clutch and kill the motor, coast to a stop, pull the plug, replace with another, ride back home.

Once back at home, take the removed plug, use a grinder with a metal cut off wheel, hold the plug by the porcelain with your hand or vice grips, cut the base of the threads with the wheel all the way around, THE PORCELAIN WILL NOT GET CUT BY THE WHEEL, becareful anyway to not cut into it....this is why its called a "PLUG CHOP"...lol.

Remove the threaded part and look at the plug, your looking for whats called the carbon ring. This will be a tiny blackish, tanish ring at the base of the porcelain.

You want this ring to be about 1/8th inch thick, making a complete circle around the plug, and evenly distributed, a lil off is fine.

The thickness also determines needle position, the full and even distribution by the main jet, if your not popping on decel, your pilot/ air fuel screw are fine.

If its slightly black or tanish, your in a good spot.

This stuff is on sites all over the internet, YOU CANNOT go based on pulling the plug and seeing tan.

I donot plug chop, because after extensive plug chops and tunning, what works for me as some of you know, is the "GO BIG OR GO HOME" method. "Even www.jetsrus.com recommends this method for main jet adjusting".

How its done: I make sure my pilots big enough to start without the choke, I leave the needle in the middle position, and get large size main jets in incriments of 5 from stock size 148 to almost 240..."I have a big bore".

I start with a large size main jet like a 190, then go for a ride, if it doesnt sputter on the topend, I go up 10 sizes, I do this till it sputters at wide open throttle from being rich, then go down to the smaller incriment of 5 till it stops. Your main is now "almost perfect" as close as youll ever get it.

I only adjust the needle if theres hesitation or a slight sputter on acceleration, if theres hesitation, its to lean, if it sputters, its to rich. If your not sure its hesitating, go rich till it sputters on accel and back it off a lil bit till it stops.

This method "WORKS" and is nearly perfect without plug chops.

It will leave you a touch rich, not by much, but BELIEVE ME THATS WHAT YOU WANT....

When you need to rejet: new pipe, new carb, big bore, filter, cams?, popping, backfiring, hesitation, elevation changes, temp changes...etc.

if I left something out, let me know, if Im wrong we can look it up and make proper corrections.

Long but informative...look it up if you have any issues...ask a question if you need to...good luck and ride hard.

EDIT: on page 4 I uploaded some pics of a 400ex plug dpr8z this plug is out of the turbo project and does not represent a good jet setting, it will show you how the plug will look after chopping the plug.... I REPEAT not a properly jetted plug by any means.

Also 99% of websites on plug reading leave out nesescary info on how to read your plug for your main jet, and can be slightly sketchy on info...they cant have you competing with them out at the track right? ;)

Heres video of what a properly tuned 440ex can do against a HIGHLY modded yfz40. This is my personal ATV, This was running a lil lean at the time.

http://www.youtube.com/watch?v=YbxcE9rHt90&feature=channel

[dalejiw25]

Thanks for the knowledgeable Thread. I don't know much about reading a plug nor do I care, But that is exactly how I've Been jetting anything with a motor in it forever. Great write up. Cheers.

[JOHNDOE83]

Thanks man, I appreciate it.

I must have wasted hundreds of $ on plugs, maybe not hundreds, but it was a waste of time, I see alot of the look at my plug, or let me see your plug stuff and alot of how to jet.

I figured this would be a tad easier, for newer guys. lots of reading tho...lol.

[bherriman]

Good post...only thing I will say is that a Slight pop on decel does not always point towards a lean condition. When you let off the throttle it creates a small vacume and will suck some extra fuel into the cylinder and the pop is just that unburnt fuel being heated by the header and "popping".

[JOHNDOE83]

Actually the carb has vents that prevent that from happening, it sounds likely, but not the case....Mine doesnt pop on decel.

When the throttle closes, the carb isnt completly shut off "like a choke", the slide doesnt close fully, if it did there would be a vaccum.

show a pic of your plug and how it should look. and ill put one up of mine to compear them. im runnig a 450 fcr carb with a 50/155 and it runs 8.40 flat in the 1/8 mile your running a 450 vac. carb with 50/220 running 8.80s not to say im or mine is better than your or that im better than you so dont take it that way. we are just running to diffrent carbs. but i will say that the fcr carb is better cuz its a mechanical carb and vac. carb dont respond as fast it has to pull vac. frist. then it will respond i dont have to wait its there. if u go to the 450 site and ask around thay are pulling the vac. carbs off and going to the newer carbs the fcr carb. the 04-05 have the vac. carbs on them. 06 and up run fcr carbs.

[guenther]

Originally posted by ericcrip
show a pic of your plug and how it should look. and ill put one up of mine to compear them. im runnig a 450 fcr carb with a 50/155 and it runs 8.40 flat in the 1/8 mile your running a 450 vac. carb with 50/220 running 8.80s not to say im or mine is better than your or that im better than you so dont take it that way. we are just running to diffrent carbs. but i will say that the fcr carb is better cuz its a mechanical carb and vac. carb dont respond as fast it has to pull vac. frist. then it will respond i dont have to wait its there. if u go to the 450 site and ask around thay are pulling the vac. carbs off and going to the newer carbs the fcr carb. the 04-05 have the vac. carbs on them. 06 and up run fcr carbs.

What does your 1/8 mile time have to do with the instructions on jetting correct? I think everyone on this site is entirely to familiar with how fast your quad is.

[JOHNDOE83]

well, that 8.4 is with a wheelie bar...my 8.8...is from sliping the clutch... ;)

lol...and your high compression...lol.

I know hes not trying to rub it in anyones face, hes just saying, unfortunatly im under going the turbo project and cant get a plug reading for you.

The 450r carb is better for what we do, drag racing, its a 42mm....I think the fcr is slightly smaller....better for mx, xc....just an opinion.

[guenther]

Originally posted by JOHNDOE83
well, that 8.4 is with a wheelie bar...my 8.8...is from sliping the clutch... ;)

lol...and your high compression...lol.

I know hes not trying to rub it in anyones face, hes just saying, unfortunatly im under going the turbo project and cant get a plug reading for you.

I know he's just saying ;) . I'm not trying to be a jerk but it gets old hearing it time after time after time after time.........

[NacsMXer]

Excellent post JOHNDOE83, thanks for the write up! :)

Right now i'm trying to get my jetting perfect as I just put a new cam in my motor. I have every circuit in the carb pretty much dialed except for the main jet.

I was using your "go big or go home" method to test the main jet circuit. With the previous cam I had in the motor, it would sputter up top with only a Keihin 170 main. Plug was dry sooty black after that.

With the new cam, I started out with a 172 main. It pulls clean, but no sputtering. I currently have a 175 main in it which is the biggest one I have on hand. Again, pulls clean, no sputter. No deposits on the plug, it's not black and it's not bone white either....a nice dark brown.

Would you recommend going higher than a 175 to a 178, 180, 182, etc. until it starts to sputter? And then back it down until it goes away? Would I possibly be leaving power on the table if I don't get to the point of sputtering (even though it pulls clean now)?

Thanks again for your insight!

[JOHNDOE83]

Honestly, you wont be leaving behind any real noticeable power, if it were on a dyno and not jetted right then jetted right after a few runs, you might gain .1 or .2 hp...lol, from what youve said it sounds like your almost there on your jetting, if your looking at a nice color now, I wouldnt stress it to much.

I like the sputter and back off method, it leaves you a tad rich, that way if the weather changes or elevation or anything else that would cause a air/fuel change, you know your good to go no matter what, also if you add a mod here or there you wont have to worry about jetting right away or at all being slightly rich. also if your trying to really get on it in a race, you want plenty of fuel with no issues.

From riding around in normal conditions, the plug will always get color after a few hours or even after a few minutes, the high rpm runs burn and blow all the color away from the porcelain, thats why when doing plug chops they always look a lil lean. and why you have to go off the carbon ring inside the plug.

Im not sure how much bigger you need to go? you have a pretty highly moded motor correct? I cant see your sig in the reply...lol. anyway if your pretty modded with a big bore then yes go big till you sputter then back off....may help that tick a lil also???

My way of thinking is its not to rich till it sputters....anything before that is clean burning fuel or to lean.

[jcs003]

here is a visual aid:

http://www.atvriders.com/articles/sparkplug.html

[NacsMXer]

I appreciate the reply, thanks.

Yeah this motor is pretty built up with high comp piston, stroker, porting, valvework, etc. so I definitely agree with you leaning towards the rich side on things. You might burn a little extra fuel but it helps the longevity of the engine i'm sure in the long run.

I was honestly expecting it to sputter with the 175, but I guess I will have to go bigger. I will never really get that "confirmation" that i'm too rich until I try it I suppose.

So say I put a 182 main in it and it sputters. If I put a 180 in it and it doesn't sputter, should I leave that in there, or go slightly leaner to a 178? Or maybe is it just as simple as going down in steps until the sputter is completely gone?



Here's my plug after the 175 runs. It's not a plug chop I know, but it was a fresh plug with minimal idling and a WOT run. If you look down to the base of the porcelain where it stops, it is a nice dark ring. It is a brown to lighter brown everywhere else. Think i'm close still?
http://img171.imageshack.us/img171/9002/dsc01739x.jpg (http://img171.imageshack.us/i/dsc01739x.jpg/)
http://img94.imageshack.us/img94/8933/dsc01754t.jpg (http://img94.imageshack.us/i/dsc01754t.jpg/)
http://img694.imageshack.us/img694/8471/dsc01750hf.jpg (http://img694.imageshack.us/i/dsc01750hf.jpg/)

[JOHNDOE83]

you have to cut the threads off to know...use the bigger jets first, then plug chop

well u did sound like a (*ss). what i was getting at is the jets he runs and the jets i run. we have the same set up but the carbs are the only thing hat is diffrent. and for the bars on the back. thay are for safty we are slipping the clutch to now and its faster slipping the clutch than just dumpping it. when he was dumping it it jumped all over the place. now that he has some drag time under him he is doing what i have been trying to teach he. drag racing is a diffrent ball game then dirt. back to the set ups we have 440 kits,stage 2 cams,p&p heads 12.5 comp. 450 carbs, his is vac. and mine is fcr mech. same rims his running 22/10/10 and im running 18/10/10. so there u go all most the same motors and like i said from the start of it if you read the frist one i put DONT TAKE IT WRONG OR ME WRONG I WAS NOT SAYING THAT MINE WAS FASTER OR BETTER. SO YES U WAS AN *SS ABOUT IT.

I HOPE U DIDNT TAKE IT WROUNG LIKE I SAID FROM THE START IT WAS NOT THAT MINE WAS BETTER OR FASTER. JUST WE RUN DIFFRENT CARBS. WITH THE SAME SET UP.

[JOHNDOE83]

your wheelie bar is to short, you need it a bit longer so you can dump and go, it helps keep it straight on take off instaed of bouncing.... on atvdragracers.com they say your bar should be the length of the quad to keep from bouncing and swaying.

You have alot more mods then me also....but thats beside the point.

I know what your getting at but there is alot more variables, in whats goin on then just our carb setup.

[JOHNDOE83]

NACS...this is where you need to look, I know it says 2 stroke but its the same place the band your lookin for is.

I cut the threads all the way off, to see the whole rotation of the band...

http://www.dfn.com/benkaren/plugchop.html

These plugs are from a car but its what you want and where to look....pics at bottom of this page....on the EX it will be slightly smaller.

http://www.dragstuff.com/techarticles/plug-pictures.html

[guenther]

Originally posted by ericcrip
well u did sound like a (*ss). what i was getting at is the jets he runs and the jets i run. we have the same set up but the carbs are the only thing hat is diffrent. and for the bars on the back. thay are for safty we are slipping the clutch to now and its faster slipping the clutch than just dumpping it. when he was dumping it it jumped all over the place. now that he has some drag time under him he is doing what i have been trying to teach he. drag racing is a diffrent ball game then dirt. back to the set ups we have 440 kits,stage 2 cams,p&p heads 12.5 comp. 450 carbs, his is vac. and mine is fcr mech. same rims his running 22/10/10 and im running 18/10/10. so there u go all most the same motors and like i said from the start of it if you read the frist one i put DONT TAKE IT WRONG OR ME WRONG I WAS NOT SAYING THAT MINE WAS FASTER OR BETTER. SO YES U WAS AN *SS ABOUT IT.

You gave a whole lot of info above but didn't answer the simple question that I asked. What does your 1/8 mile time have to do with the instructions on jetting a quad correct? I never said, nor implied, that you were saying your set up was better than his. I didn't mention anything about the wheelie bars either. I guess what I am trying to get at is that you seem to work in the fact that you can run a 8.4 in the 1/8th mile in MANY of the threads you post in. We ALL know this and have seen it over and over. You can think I'm an "a (*ss)" as you put it, I'm okay with that. However, I'm sure that many others on this site share the same sentiment that I do. I'm not saying you're a bad guy or an "a (*ss)", but maybe it's time to ease up a little. Have a good one.

JOHNDOE83, I'm very sorry about hijacking your thread.

[JOHNDOE83]

More good info...says everything ive said.


http://www.dragstuff.com/techarticles/reading-spark-plugs.html

[JOHNDOE83]

Also just from riding aroud and pulling your plug, that will only tell you your needle and pilot position and has nothing to do with the main jet.

[jcs003]

john, anything you can tell me about having a gray electrode strap and the visible part of the porcelin being gray? according to the pug color chart im in an ok range.

i richened up my lectron for my engine break-in. this is on my 250r. any thoughts?

[JOHNDOE83]

I know 2 strokes are a bit different, I think the slight grey comes from the oil mix? I also hear that the gas now a days burns a lil different and that higher octanes burn a lil greyish?

as long as your running the right type of octane for your compression, your oil mix is good, and the jetting scheme matches that of the pics you were looking at, id say you were good.

I know my go big or go home method isnt really for 2 strokes, I also know that 2 stroke plugs will have a darker then tan color, greyish or blackish, even be slightly wet when jetted proper.

break in on 2 strokes should be rich....so I think just from what youve told me...your good enough to not worry.

after the break in, you should do a plug run, cut the threads on the plug and check the carbon ring to make sure you top end jetting is good 2 go....I think 2 strokes need that more then anything, if they run lean in high rpms, it could be hurt full?

Is that what you were looking for?

[MtnEX]

I think it is not so much intentional mis-information out there as it is that the FUELS have changed... and plug reading has changed with it... but few of the plug reading guides say the same thing.

[MtnEX]

Now with the above said, I am going to post a few general pictures of plugs to see what kind of reading you guys get from them... without the actual chop....



Black at the end of the threads...

Black on one side of the porcelain, white on the other...

[MtnEX]

Back if ground strap... and coloring in the threads...

[MtnEX]

One with several different color patterns...

[JOHNDOE83]

Originally posted by MtnEX
I think it is not so much intentional mis-information out there as it is that the FUELS have changed... and plug reading has changed with it... but few of the plug reading guides say the same thing.

exactly!!! thats why you cannot just pull a plug and get a proper reading!!!

About your posted pics and plug reading test....lol.

Just from looking at the plugs color without knowing what type of motor, modifications, compression or fuel or how long the plug was in there?...which are key elements.

Its anybodys guess? I am in no way an expert on plug reading, but just from taking a guess, I would say.

The first pic appears to be rich.

The second, appears to be to hot on the plug, or to lean, or fresh from a plug run?

The third looks as if its either a high octane fuel, or the first plug in the pics cleaned off with carb or brake cleaner...lol.

Like I said...Im not claiming to be an expert, plugs cannot be read from just pulling it and looking at it, thats why I made this thread, to show the proper way to do a plug chop!! And that everyone fails to read the carbon ring, and the best way to jett without doing numerous plug runs.

Im curious to see whats wrong with those plugs? from another point of view? can you chop em and post the pics again? Id like to know what reading you got also?

[MtnEX]

Well, they are all different plugs out of the same engine... same fuel and octane...

The only difference is different fuel % and timing... and also when they were really taken out, like after a plug run or just a ride, etc...

These are out of my KFX450R at different times as I mess with tuning.


To me, it is very hard to tell about air/fuel ratios from the plugs anymore.


To me a couple of those look rich and lean on the same plug... because...

1- not used to seeing black
2- not used to seeing white

Usually you would get a gray or brown coloration of some degree all over a good burning plug seeing good air/fuel ratios.

Now that's just not the case all the time... or I'm missing something....

[JOHNDOE83]

well if you go back and read threw the main topic post, the part you see when just looking at the threads is only going to determine heat range and partial pilot and needle setting, timing...etc. it will NOT show main jet just from looking at the plug.

Thats why I use my "Go Big Or Go Home" method.

I totally by passes the plug chop, and could be done easier and in half the time.

if your pilots big enough to start your motor without the choke, its good.

If your not hesitating or sputtering in the mid, your needles good.

If your unsure on your main jet, go big till your top end sputters a lil bit, then back off the jet size rougly 5 sizes, and youll be jetted perfectly.

If you need to be sure? do a plug run after the above stated info, and cut the threads off the plug and check the carbon ring.

That is the proper way to jet!...with these fuel additives.

[MtnEX]

And here is what I think I have learned the hard way while trying to make the uneven porcelain coloring go away...

[MtnEX]

And what I think I have learned about timing and heat range...

[MtnEX]

This ground strap appearance is a confuser to me though...

Doesn't look like what I am used to and the timing was not changed...

Gray without what you can pick out as a timing mark.

[JOHNDOE83]

One reason why they say poping on decel is ok, is that the pilot only effects up to like 1/4 throttle at most, so if its only at 1/4 or below it will not hurt your engine enough to cause damage.

So if your rich on your idle, which is the black on the threads, its a good thing, it means youll have the low end torque you need and will keep you from backfiring.

the ground strap only shows your plugs heat range, if its in the middle, your heat range is good, towards the tip, to cold, at the threads, to hot..

The porcelain that everyone thinks is the way to determine jetting, when its "TAN" is the timing and detonation part of the plug....not for jetting.....the "tan" comes from the needle after riding from several hours.

chop the plug and post a pic of it!

[MtnEX]

Originally posted by JOHNDOE83
well if you go back and read threw the main topic post, the part you see when just looking at the threads is only going to determine heat range and partial pilot and needle setting, timing...etc. it will NOT show main jet just from looking at the plug.

Thats why I use my "Go Big Or Go Home" method.

I totally by passes the plug chop, and could be done easier and in half the time.

if your pilots big enough to start your motor without the choke, its good.

If your not hesitating or sputtering in the mid, your needles good.

If your unsure on your main jet, go big till your top end sputters a lil bit, then back off the jet size rougly 5 sizes, and youll be jetted perfectly.

If you need to be sure? do a plug run after the above stated info, and cut the threads off the plug and check the carbon ring.

That is the proper way to jet!...with these fuel additives.

I think you are right, because if I try to clean up the smooth part of the metal below the threads there... it will clean up with less fuel but will not start for crap... LOL...

And the 400EX needs to be even richer to start well. Ticks me off because it starts well with a 42 pilot, but stumbles when you stab it off idle after it warms up. Too much jet or my compression is getting lower.


As for doing plug chops... On the 400EX you can just pick up Champion Powersports plugs... run them, then look down at the bottom of the porcelain. You can just look and see without cutting this plug.

[JOHNDOE83]

Originally posted by MtnEX
...

And the 400EX needs to be even richer to start well. Ticks me off because it starts well with a 42 pilot, but stumbles when you stab it off idle after it warms up. Too much jet or my compression is getting lower.



That might be your needles to rich? or to lean?

[MtnEX]

Originally posted by JOHNDOE83
That might be your needles to rich? or to lean?

Maybe...

I never did try moving it either way while I had the 42 pilot in.

[JOHNDOE83]

you said it stumbles? without being there I cant know what you mean? that could be a sputter or a hesitation?

go lower with the needle clip, if its worse, go higher, see what happens?

[JOHNDOE83]

This is out of my turbo project, NOT A PROPERLY JETTED PLUG!!!

but this is how it will look after the plug "CHOP!"...lol.

This was ran in my atv for almost a year, then ran on numerous runs with the turbo....its not a guide on how it should look being that its jetted horribly wrong and not after a plug run!!!

You can "almost" see the remnants of the carbon ring from previously jetting setting. the camera sucks and the light was akward but if you look its there.

If you can see the ring im talking about, and know how to add a line pointing at the ring to show where it is or would be? please feel free to edit the photo if possible?

http://i953.photobucket.com/albums/ae15/johndoe83_2010/Picture0062.jpg

http://i953.photobucket.com/albums/ae15/johndoe83_2010/Picture0060.jpg

[MtnEX]

Yes, I will do that for you later... and post it up....

[TRXRacer1]

I can tell the air temp, elevation, sex of the rider and month of the year from my plug chops.

[JOHNDOE83]

LMAO...thats funny.

what about hair color?

[TRXRacer1]

Originally posted by JOHNDOE83
LMAO...thats funny.

what about hair color? Haha, sometimes but it's not a 100%.

[honda400ex2003]

Originally posted by TRXRacer1
I can tell the air temp, elevation, sex of the rider and month of the year from my plug chops.

freaking awesome! I am glad you finally decided to come back to exriders! you make a bad day better lol. steve

[MtnEX]

Here is what I think you were looking for?

[MtnEX]

...and the other one as to not confuse folks...

[JOHNDOE83]

Yeah thats perfect!!!.....called a carbon ring but its ok i get them mixed up once in awhile also....i think throught the thread ive got em mixed up a few times.

Good eye!!! and great example of where everything is at!!!

[MidnightBlade]

explain hesitation and sputter at WOT, is this just from idle to WOT or getting to WOT over time? if someone could post a vid would be most appreciated

[JOHNDOE83]

the sputter at wot, will be like the rev limiter kicking in to early.

on topend...hesitation is hard to tell, but if you go buy the sputter and back off method, if you were hesitating before...youll see the difference.

it will also feel like your rpms from idle to high will get up fast, then kinda slow down after mid to higher rpms, like torque then flat in any gear under heavy acceleration.

it should rev out as fast in the higher rpms like it does in the lower rpms..

[MtnEX]

It's hard for me to decide what is sputter and what is hesitation also when stabbing it off idle...

So that is why I never said.


I'll just have to go back and try.
But right now my front brakes are out.
Dang screws broke off in the reservoir cover!

Can't get them out to save my life.
Guess I will have to buy new or ebay for the whole thing.
Can't spend a penny right now though.

[Wheelie]

MtnEX--When you are talking about stabbing the throttle from an idle, are you doing this is neutral or under a load?

[MtnEX]

It's been a while now... but I think it did it both ways....

[NacsMXer]

JOHNDOE83, here are my GoPro vids using your "go big or go home method". Please don't flame for being on the street, this is a private neighborhood and i'm just going around the block real quick. I don't have anywhere else to go WOT nearby.

All the vids are 3rd or 4th WOT runs. I started with a 175 main, then a 178, and ended with a 180 main. I believe I have found the rich stumble with the 180 main, listen to the motor in the vid. Listen specifically at 0:18-0:19 and 0:31-0:32. 175 seems to pull the best and sound the cleanest from the vids.

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[TRXRacer1]

175 sounded the best. :muscle:

[honda400ex2003]

cheers to that :D steve

[honda400ex2003]

after my ride this weekend i will do the same thing i think. I gotta test this for myself. steve

[NacsMXer]

Thanks guys. I'm tempted to go back to a 172 but not sure if I will. I want the motor to have good power, but still not be too lean at the same time. I want a jet I can have in there and go WOT all day if I wanted to without worrying something was going to melt down.

As you can see, with a FCR 39 and my mods, 175-180 main jets all pull reasonably well, but there's very slight differences between them. That's what makes jetting so tricky IMO, there's a lot of fine tuning to be had.

So final jetting, FCR 39, mods in sig:

Pilot: 55
Fuel screw: 2.5 turns out
Needle: OCEMP middle/4th notch
Main: 175
Main Air jet: 200 (standard size)
Air Screw: 2.25 turns out (standard setting)


And on a side note, my new +1.5 swinger and reworked PEP ZPS rear REALLY tames the wheelies. You can see it in my 175 main vid. I used to be able to throttle it up in 3rd-4th (+1 forward arms/stock swinger), but now it keeps the tires planted. It shows how offset arms and extended swingers change the weight bias. Just point and shoot now, I can't wait to hit up the track :macho

[JOHNDOE83]

Nice, Im glad everything worked out, from watchin the vids you can see the difference in the front end also, with the 175 when you gas it, it seems to pick up a lil faster then it did with the 180.

I usually wined it out a lil more, but I deffinetly heard the stumble on the 180, so you did good on reading the bike.

You got a sweet quad there!!!

[TRXRacer1]

Originally posted by NacsMXer
Thanks guys. I'm tempted to go back to a 172 but not sure if I will. I would say no. You found the ceiling with the 180 and the 175 is the perfect back off. I bet if you dyno tuned it they wouldn't touch that main either.

[NacsMXer]

Originally posted by TRXRacer1
I would say no. You found the ceiling with the 180 and the 175 is the perfect back off. I bet if you dyno tuned it they wouldn't touch that main either.

Yup i'm feeling the same way. And even if I did gain a little power leaning it out a tad, the actual HP increase would be pretty negligible. I'd rather the motor run richer and slightly cooler in the long run.

Thanks again JOHNDOE83, your method totally works!! :D

[honda400ex2003]

so you went up one jet size from a 172 to a 175? steve

[honda400ex2003]

Originally posted by NacsMXer
Yup i'm feeling the same way. And even if I did gain a little power leaning it out a tad, the actual HP increase would be pretty negligible. I'd rather the motor run richer and slightly cooler.

Thanks again JOHNDOE83, your method totally works!! :D

you should do one with the 172 in it too. see in my opinion after watching it again, the 175 sounds rich at around 6000 rpms-7000 rpms imo, it had a weird bog sound to it before you would about half a second or so before let off the gas. I didnt actually watch them earlier with sounds cause i was at work. the top one looked the best out of the three just by rides sake. do you know what the temp of the engine was also by chance? my guess would be around 150-170 degrees. it will richen up as it gets to full operating temp of around 200-210. I am not trying to be picky here just trying to see what the conditions were and such. steve

[NacsMXer]

Originally posted by honda400ex2003
you should do one with the 172 in it too. see in my opinion after watching it again, the 175 sounds rich at around 6000 rpms-7000 rpms imo, it had a weird bog sound to it before you would about half a second or so before let off the gas. I didnt actually watch them earlier with sounds cause i was at work. the top one looked the best out of the three just by rides sake. do you know what the temp of the engine was also by chance? my guess would be around 150-170 degrees. it will richen up as it gets to full operating temp of around 200-210. I am not trying to be picky here just trying to see what the conditions were and such. steve

I did try a 172 on my way up to the 175, but I don't have that run on video. I could try to get one just for the heck of it. It pulled similar to the 175, no drastic difference. Don't know the bog you are talking about, at what point in the 175 vid is it?

And you are correct, the oil temps (not engine temps) in the vids were no more than 170 degrees. My supercooler setup is like too efficient on the street lol, I couldn't get it to go any higher. That was totally without using the fan also since I was trying to get the engine as warm as possible. I've never seen the oil temps anywhere near 200 since I got the temp dipstick. I'd really have to flog it hard on a hot day for it to get there it seems. Think that would really make much difference in my jetting?

[honda400ex2003]

I think it makes a huge difference in jetting myself. especially for the guys that drag race. they surely dont have their engines at full operating temp unless they let them run for 10 minutes prior to it. I dont see many drag strips letting guys do that. Maybe after 4-5 runs it would be close. this imo is a major contributor to having such big jetting. once warmed up it richens it up. steve

[honda400ex2003]

Nacs, I finally got my comp going at work so i can have sound again. imo 31 seconds sounds like a bog just before you let off the gas and 47 seconds sounds a bit messy. start at aroune 26 seconds right as you come out of the corner, then listen to it all the way to 49 or so. that is where i was thinking though. steve

[NacsMXer]

Ok I did a run with the 172. I added it with my other vids for easy comparison. It was a 172RD jet though and not a Keihin jet, so i'm going to fix that soon.

It was hot today, close to 90 out. I also got the motor as hot as I could get it prior to my runs. The oil temp was about 190 degrees.

In the new vid, I noticed my pilot or something acting funny. I did change the fuel screw to 2.25 turns out from 2.5, so not sure if that had an effect. There is a slight stumble or something when I go to light throttle tip in (1/4 throttle) from cruising. In the vid you can hear it at 1:12-1:13, 1:14-1:15, and 1:16-1:18. It also "misses" on me once at 1:55 when I go to take off from a stop. It never did this before. I don't know if it's from the heat and the pilot is getting richer or what. Let me know what you think please.

Also let me know how the 172 sounds at WOT compared to the 175 run. Thanks again for everyone's advice :)

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[honda400ex2003]

imo after watching the 172 and the 175 runs the 172 sounded better to me. i would go in to 2 turns out if it was me. it was idling pretty low imo also but i like to have it a bit higher. it sounded like it had a bit of a rich gurgle to it when you let off the gas, that is my opinion. the heat can cause it and most likely did. it can play with your mind lol.

just a matter of opinion i guess. there is actually a way to tune the f/a screw pretty easy. ill find it and post it up. steve

[honda400ex2003]

1) Warm up the engine to full operating temp.

2) Turn up your idle a few hundred RPM using the throttle stop screw (basically you want a fast idle). This will make it easier to hear small changes in RPM. Watch for overheating--pointing a big shop fan at your engine will help it from getting too hot during the fast idling. The whole procedure shouldn't take too long though.

Each time you change the screw setting 1/4 or 1/2 turn or so, wait about 5 seconds to let the idle speed normalize. It usually take the carb and engine a moment to react to the change.

3) Turn the fuel screw IN until the idle starts to drop and miss. The engine should die if you bottom out the screw. Your pilot jet is too big if it doesn't die when the screw is bottomed out--it should die before it gets that far in.

4) Then begin turning the fuel screw OUT. The idle should peak and become smooth. Keep going and look for the idle to begin to drop/miss again.

5) The goal is to find the setting that provides the highest and smoothest idle. If it's unclear exactly were that point is then set to the midpoint between step #3 and step #4. For example, if the idle starts to drop at 1 turn out and starts to drop at 2 1/2 turns out then 1 3/4 of a turn out should be the correct setting.

If the peak/smoothest RPM is reached somewhere between 1-3 turns then your pilot jet is correct (the 1-3 turns applies to most carb types). If you end up less than 1 turn out then your pilot jet is too big and you need a smaller one. If you end up more than three turns out or the fuel screw seems to make little difference as you continue turning it out than you need to go up (bigger) on your pilot jet.

To re-emphisize: If the idle never drops when you're turning the fuel screw in, you need a smaller pilot jet. If the idle never drops when you're turning the fuel screw out, you need a bigger pilot jet.

6) Once you've got the fuel screw set, re-adjust your throttle stop screw (idle screw) to an appropriate idle speed.

And that's it! Your pilot circuit is now VERY close to ideal. From here you can experiment with how small adjustments affect low-end (i.e. small throttle openings) response and make adjustments for weather. The hardest part is usually gaining access to the screw while the engine is running. Also, you may really have to listen carefully to detect the rpm changes in the idle. 100 or 200 rpm differences can be tough to detect when the change happens over several seconds.

steve

[JOHNDOE83]

Its kinda hard for me to tell, I think the 175 was better?...but for me it was hard to tell?...plus you said its hotter out?

when you get to almost top RPMs it kinda sounded like it hit a lean spot.

I said before I wined it out a lil more, cause the main jet and needle work in conjunction till that last 1/4 bit of throttle, then your on the main jet after that.

Do a plug run and plug chop for chits and giggles with the 175, and try to do one on the 172?

I really wanna upload video of mine, only prob is my cam only takes 10 seconds of video....lol....its really just a camera that has a video option...lol.

But ima try to get video of it soon, I want you guys to see what the power band is like on mine.

[honda400ex2003]

http://www.dragstuff.com/techarticles/how-to-read-plugs.html

good info with pics. thats how the drag guys do it for quick reference on how the plug looks.

steve

[NacsMXer]

Originally posted by honda400ex2003
http://www.dragstuff.com/techarticles/how-to-read-plugs.html

good info with pics. thats how the drag guys do it for quick reference on how the plug looks.

steve

Thanks for the link. Now these guys are saying you read jetting off the base ring of the threads? And "Do not look at the porcelain to read jetting !!! " :confused:

[NacsMXer]

Originally posted by JOHNDOE83
Its kinda hard for me to tell, I think the 175 was better?...but for me it was hard to tell?...plus you said its hotter out?

when you get to almost top RPMs it kinda sounded like it hit a lean spot.

I said before I wined it out a lil more, cause the main jet and needle work in conjunction till that last 1/4 bit of throttle, then your on the main jet after that.

Do a plug run and plug chop for chits and giggles with the 175, and try to do one on the 172?

I really wanna upload video of mine, only prob is my cam only takes 10 seconds of video....lol....its really just a camera that has a video option...lol.

But ima try to get video of it soon, I want you guys to see what the power band is like on mine.

Not sure what you mean by winding it out more? I felt like I was revving the piss out of it lol...almost to the limiter. I think the vid is a bit deceiving as far as speed and sound?

I put a genuine Keihin 175 in it this time. Seeing how the K178 revved out clean, but seemed fat, and the K180 had a bit of a rich stumble, i'm sticking with the K175 main jet.

I was running 172RD and AB175 jets in it before, not knowing any better. They were just sitting in my jet collection and had the right number so I used them. These are actually aftermarket jets made by a company called Precision Engineering. If you compare them to a Keihin jet, the orifice is up higher in the jet (away from the fuel), and the taper around the orifice is also different. Because of this, they run differently off the needle and all around. They are not calibrated the same as Keihin jets, much like Dynojets, so they shouldn't be mixed with other Keihin jets during testing.

[TRXRacer1]

Reading plugs for jetting is like using witching sticks to find water. At best it should be used as guide but never as something you can rely on. One man's "science" will be different then the next.

[NacsMXer]

Originally posted by TRXRacer1
Reading plugs for jetting is like using witching sticks to find water. At best it should be used as guide but never as something you can rely on. One man's "science" will be different then the next.

I've heard this same thing before from motor builders which is why I sort of gave up on the voodoo of reading plugs. A lot of people advise to simply jet it based on how it runs, and that seems to be giving me good results so far.

[JOHNDOE83]

Originally posted by NacsMXer
Thanks for the link. Now these guys are saying you read jetting off the base ring of the threads? And "Do not look at the porcelain to read jetting !!! " :confused:

That same website is what I posted earlier in this thread for plug chopping to read the carbon ring, it still says not to read the porcelain color, which I stated earlier also. If you look back, the link is on page 2.

Your not looking at porcelain color, your looking for the carbon ring inside the plug on the porcelain to determine main jet.

The jetting they are explaining in the link steve posted, is mainly for pilot jet and needle, for all around riding and racing but doesnt accuratly determine main jet, main jet will be the carbon ring inside the plug.

How would you determine the full jetting range from just the base ring....you really cant, you need to read for several different areas to get the full range of jetting, still they will never be 100%.

Theres a thread that was posted recently, where the guy didnt have his jetting right, he put the needle on the fourth clip and went for a ride and pulled the plug, then he saw tan on his porcelain and figured he was getting close, that tan was a result of the needle being to rich, it colored the porcelain only after a short ride from changing the needle to the richest setting. This shows that that color on the porcelain that most people think is the way to jet, its only for needle position after extended ride time.

I agree with trxracer on the plug reading, it isnt 100% and it is kinda hit or miss, but after the go big or go home method, using a plug chop is to see how close it is after the go big method, kinda like doing 2 tests in one, it just helps you get it that much more accurate. Which it will never be 100% anyway. This just gives you 2 tests to get it as close as you can.

Essentially ,what you wanna do is all three methods, go big, then go off the porcelain and base ring, then go from the carbon ring on an actual plug chop, this way you now have three jetting methods combined that are all correct in some way and all have basically the same principles on color.

It may be the video that makes it sound not completly wound out.

[JOHNDOE83]

Heres a link I found on that same site, theres some interesting info about retarding the timing in there also.

http://www.strappe.com/plugs.html

[NacsMXer]

Excellent info JOHNDOE83, thank you very much! :)

[JOHNDOE83]

LOL, I just saw thats even www.jetsrus.com in the FAQs section, recomends my "go big or go home" method for main jett adjusting.

[honda400ex2003]

8 pages lol. i guess ill throw out one more reason to start something. :D


like stated before, that is a fine way to do jetting. everyone has done this forever. you arent creating anything new here. just starting with the biggest though is stupid and a waste of money. you have to buy numerous jets instead of 3 or 4 instead of possibly 10 or more. there is no way you will get to peak performance just going with "until the stumble is gone"It also states that you should do the pilot first then the needle and so on. not the main first as most of these guys try to do. get the lower stuff correct before moving on. much easier that way and would help with some of the issues people have. a recommendation is not a shot in the dark for most people, most are a very thought out, prediction about the given attributes of their situation. reading the plug can be fine to a point, match the pictures to your plug and see how it is. the problem with reading plugs is that the chops are not long enough and thus gives false readings. lots of repeat but worth a reminder after 8 pages of gobbly gook. lol. we gotta sift out that to get to the real thing at hand here, jetting based on plugs and how to do something about how to jet properly.

steve

[honda400ex2003]

Originally posted by JOHNDOE83
LOL, I just saw thats even www.jetsrus.com in the FAQs section, recomends my "go big or go home" method for main jett adjusting.

exactly why it is not your method but someone elses. lol steve

[MtnEX]

I gotta totally agree with Steve...

I also gotta say he was a huge help to me when a lot of things happened on my end and got me very frustrated with jetting beyond anything I had encountered before.

It all started from the guy who did my pipe and filter putting the wrong brand and type of main jet in.

He put in an RD Precision main (wrong brand) that was short and round with a screwdriver slot (wrong type).

It worked, but not right. It was un-tunable!!! And small changes really effected how it ran.

It was usually OK in heavy throttle (short term) but would not start cold for crap. Start and die 19 times before it would stay running no matter what the fuel screw adjustment. Yet it never popped in any way on decel.

In the middle it was safe, but never spot on. Make the needle richer and it started better, but was lazier in the middle on acceleration. Get it better in the middle and the starting was worse than ever.

So I went to rejet... and low and behold, my Honda dealer sold me the same wrong jets for main jets.

It started well with a 42 pilot, but stumbled off idle with a hard stab every time like it was too rich on the pilot no matter the fuel screw setting.

I got to a point where I had myself backed all the way down to a 40 pilot and the right type 150 main with a pipe and filter. It ran fine... not lean or anything it didn't seem, but still didn't start well cold.

I would not go back to the 42 for the stumble... but I stayed persistent and Steve helped out.

I moved to a proper 155 main, and low and behold I started getting a pop on decel with the 40? So I went to the 42.

Now it just barely doesn't pop on decel, starts good and runs pretty darn good.

Moral of the story is....

That there is a pretty good size range of OK jetting that won't blare out at you about being rich or lean.

There is some bleed-over from circuit to circuit that causes some cross effect that can be hurtful or helpful... but getting all aspects as spot on as possible is best.

Pilot needs to be the right size, fuel screw needs to be properly set, and idle speed dialed in... and the needle and main need to be close as well, else you chase your tail.

And use only carburetor brand jets!

I have a bit more playing to do with one size up on the main, one size down on the main, and some needle play before I am certain what seems to be best.

[JOHNDOE83]

Originally posted by honda400ex2003
8 pages lol. i guess ill throw out one more reason to start something. :D


like stated before, that is a fine way to do jetting. everyone has done this forever. you arent creating anything new here. just starting with the biggest though is stupid and a waste of money. you have to buy numerous jets instead of 3 or 4 instead of possibly 10 or more. there is no way you will get to peak performance just going with "until the stumble is gone"It also states that you should do the pilot first then the needle and so on. not the main first as most of these guys try to do. get the lower stuff correct before moving on. much easier that way and would help with some of the issues people have. a recommendation is not a shot in the dark for most people, most are a very thought out, prediction about the given attributes of their situation. reading the plug can be fine to a point, match the pictures to your plug and see how it is. the problem with reading plugs is that the chops are not long enough and thus gives false readings. lots of repeat but worth a reminder after 8 pages of gobbly gook. lol. we gotta sift out that to get to the real thing at hand here, jetting based on plugs and how to do something about how to jet properly.

steve

I never said I was creating anything new.

I never said to start with the main jet, I kinda said to start with the pilot then the needle, then main.

Jetting based on plugs I also said wasnt the best, and could never be spot on, but is a good way to run tests to see how well you are jetted, the carbon ring on the plug is for main jet.

Earlier I even said use the three different jetting and plug reading methods to be as close as possible.

Plug color really has nothing to do with it, Ive said that numerous times, and all the posted sites also say that the porcelain color is NOT for jetting.

Jetting for peak performance would be to run it lean, which isnt the best.

Steve, I feel that you still need to do a plug chop, or atleast see how many jet sizes till you sputter, dynos are cool but people will let you run and tell you whatever you want to hear for your money.

RD jets are OK to use, any type of jet that screws in to the jet holder will work, but you have to actually know how to jet to know what your doing.

One or two sizes up or down is pointless in jetting.

Theres just so many things to say here, but really no one here is wrong, we all just have different ways of saying things.

But for you guys to say Im flat out wrong or misguided is deffinetly not the case, this is not gobbly gook, I think you guys just arent understanding part of whats going on here, which is fine, sometimes Im very vague in my responses and posts which I do on purpose, not to be rude or mean, but so that some people can figure things out on their own, like planting seeds...lol.

Shoot sometimes I get things wrong, I know what im talking about but get ahead of myself and sometimes and type before I think, which seems like alot of us do, but like I said, none of us are really wrong here, if you look back and read everything, we are on the same page, just doing things differently.

[honda400ex2003]

I cant even bring myself to do something like that again. i know i would be right back where i am now if not one jet size smaller than i am at for the heat. i had a 178 in there when i took it down and it did not run as good as it does now so i have actually done what you want me to do. I have in access of a 182 in there before getting down to what i am at now. it didnt really bog too bad with the 182 in there, but why should i run that when i can run something smaller? I can get another 5 miles to the gallon going down in jet sizes. I dont care about hp, i like gas milage. it is not hard for me to put on 70-90 miles in a day without thinking about it. you on the other hand ride down a drag strip for the most part. you dont need to get 40 miles to the gallon so you dont have to carry 2 or 3 gallons on the back of your machine. I gained a whole horse going from the 178 to a 168 and probably could have gained another .5 or so going down a bit more. This doesnt seem like much but you can tell when it runs bad when it is rich. It wheelies a gear higher now than it did when i got it in. steve

[JOHNDOE83]

Here is the video I said I was gonna get of my quad running, this was running lean at the time with a 195 main jett. racing against a highly modded yfz450.

http://www.youtube.com/watch?v=YbxcE9rHt90&feature=channel

[JOHNDOE83]

bumped for people that need jetting help.