Spark Plug color

[bkb88]

I believe I am getting close on my 406ex jetting. The picture below is from a new plug after about a 1.5 hour ride varying the rpm range. My jetting specs for this were:
#165 main
#40 pilot 3.5 turns out
needle on stock position

http://i100.photobucket.com/albums/m14/thebutelr/SANY0549.jpg

I am still noticing a little bit of popping on deceleration and a faint very soft backfire (almost a puff) when my engine is shut off after being ran for a little while. I tried running my bike with the needle set on the 4th slot and it would barely run through the 1/4-3/4 throttle range.

Would going to a #42 pilot at around 1-1.5 turns out and leaning my main to around a #160 put me close to spot on? IMO this plug is looking like the carb is slightly rich on the main and lean on the pilot. What do you guys think?

[JOHNDOE83]

Im glad to see your doing a proper plug chop!!

BUT, it looks to rich for the main jet, the popping is from the pilot jet, try to to turn your air/fuel screw out to 3 turns.

Back down your main jet to a 160 and try again, the band on yours is too big, try a new plug and chop it again, tyour looking for that band to be about 1/8th in, or smaller,. Yours is a lil big...lol.

Any stuttering or rev limiter hitting at wide open throttle?

[bkb88]

Thank you! I have tried doing the WOT 10 second, clutch/killswitch, roll to a stop run several times and it seems to not be near enough time to put any color on a new plug. I have read on several sites stating that it is virtually impossible to get an accurate reading on a new plug using the traditional plug chop method due to the high amounts of detergents found in modern day pump gas.

As for the WOT performance I have not hit the rev limiter yet and I have had the bike pinnned at WOT for an extended period of time just to see how it ran.

I have also noticed that when I give it a quick rev that the rpm's will not go down as quick as it used to. It is very subtle but still noticeable.

The climate here in Southern Illinois is extremely humid. That probably would explain why my jetting seems to be rich running the settings that many others use on this forum with similar mods.

[JOHNDOE83]

I forgot to add that 3 turns out on the air screw was for a 42 pilot.

if your 3.5 turns out on the air/fuel screw with a 40 and still backfiring on decel and getn a lil puff when shut off, then you still have a lean pilot.

It seems as if your on the right track, let us know the outcome.

[bkb88]

Okay guys, just for the sake of keeping things simple I decided to only change the main jet for this plug run. Everything else has been left alone except for changing the main to a #160. Here is how my plug looked after another hour ride. The last runs I made with this were using a friends GPS on his phone to see how fast my bike would run so this should be a pretty good indication of how my main jet is doing.

http://i100.photobucket.com/albums/m14/thebutelr/SANY0557.jpg

I believe I found the problem causing my 42 pilot & 4th clip on the needle setting to run so bad. The carb had part of the intake pinched causing extra air to enter into the system causing a false indication of being too rich. IMO the plug should be brown throughout after a long ride. I will be buying more plugs today so should setting my needle on the 4th clip solve my 3/4 white plug problem?

I am also seeing a faint puff of black smoke when I slightly open the throttle from closed to about 1/8. Could this just be the accelerator pump out of adjustment? When I am riding I have noticed a slight hesitation when I go from 1/8 to about 1/4 throttle, is this also an indication of a lean needle jet setting?

[CJM]

Before you do much else:
1. Set the needle to the 3rd notch from the flat end
2. Try a 162 main.

I betcha it runs great after that.

[bkb88]

I will have to order a 162, seems like that's the only one I don't have haha. My needle clip is already on the 3rd notch from the top (stock). It seems to run okay right now except for that slight hesitation when going from around 1/8 to 1/4 throttle. Should it not have color all the way through after running it for about an hour??

[JOHNDOE83]

That plug looks good!

But as cjm suggested, Id also bump it up to the 162 but for now your looking good!

That hesitation would be from the needle position, maybe richin it up 1 notch or maybe try adjusting the pilot more and see if that helps, if the pilot isnt a simple fix for the hesitation then try the needle.

[CJM]

There may always be a very slight hesitation, sometimes its hard to get rid of. Adjusting the needle, pilot and air/fuel screw should work, just finding the right combo.

In my case I jetted slightly richer than needed (1 size up) just incase-you just never know based on where you might ride, temps could be extreme, crappy gas-etc.

[MtnEX]

Nice plug reading/jetting thread guys.

I am too lazy to chop them like that... so I look at them with a pen light... like an LED.

Need to jack one of those things at the Dr's office that he uses to look in the kid's ears... LOL...

I have spent several quads worth of money there... LOL...

[bkb88]

Here's a little update:
I have tried moving the needle clip to the 4th slot and have found it to be too rich. The bike wouldn't rev without a slight sputter in the mid range so I moved it back to the 3rd slot and that's where it will have to stay. I have not messed with the pilot yet due to the brand new plug I put in showing up completely black from idling about 10 minutes. I am still getting a small puff of black smoke when I slowly open the throttle from 1/8 to 1/4 after it has idled for about 10 seconds.

This seems like my 40 pilot is a bit too much for my bike in this humid/hot climate. I am suspecting an air leak that is causing my slight popping on deceleration. Is there a good way to check for exhaust leaks?? I installed new copper crush gaskets when I rebuild my engine but I have not looked into sealing the section where the header meets the silencer. Is there some type of sealant that is supposed to be used instead of just using the exhaust clamp?

Other than the slight popping the bike runs great so I will be leaving the jetting as is until I purchase a #162 main to switch out my #160. I really appreciate all the helpful posts guys.

[CJM]

Black smoke is rich, perhaps the pilot and or main is too rich-but like you said cant be sure till you get the main dialed in better.

As for the exhaust, stock you shouldnt need any sealer. If you have anything else then some hi-temp copper gasket maker silcone is what I seal it with.

You can check for leaks while its running, put your hand (use a rag over it) and seal the end of the exhaust. Air escapes then you got a leak, otherwise your good to go.

[bkb88]

I am losing my mind trying to tune this bike... I now not only have problems with my slight sputter when gently opening the throttle from 1/8-1/4 throttle, I have issues with sputtering in the mid range. It seems like I cannot keep a steady rpm holding the throttle in anything from 1/4-3/4 throttle. It feels like it is "surging" in that throttle range. I tried placing the needle clip on the 4th slot and had exactly the same result as before, it runs like it has the choke on.

Could I possibly be running into timing/electrical issues now???

[MtnEX]

Have you checked the compression, valve clearance and timing?

And have you verified that your screws didn't come loose on top of the slide?

And have you checked the synchronization between the slide and throttle butterfly?


These things will make one impossible to tune out. So will a leaky needle/seat or improper float level.


You'll get it or figure out what's preventing you from it in time.

You might loose the rest of your mind, and some of your hair, but you will get it... just be persistent and logical.

[bkb88]

The bike definitely seems to have great compression although I have not performed a reading with a compression gauge. The valves could possibly be out of adjustment since I had it apart last time but could that really make it run rough in only one rpm range? I have never heard of setting the butterfly synchronization before, what are the steps to doing that?? Also, I am 100% positive that the screws are nice and tight on the top of the slide.

Does it affect anything when a timing key is installed while you are setting the cam timing?? What I am trying to say is does it have any effect on the way you set the timing or is it the same as if no timing key were installed? I am pretty confident that I had the timing set correctly but there is always a chance that it might be off slightly. I have noticed on the carb that there is a lot of scoring on the throttle slide. Is this an indication that my carb is pretty much completely worn out? The previous owner did not ever maintain this bike and put it through some major abuse.

I'm trying to narrow this down to one possible area or the other instead of looking around for problems all over the bike (timing, carb, electrical, etc.). If it sounds to everyone like a timing issue I have no problem with taking off the valve cover and starting from scratch. I feel I should mention that the bike still has a slight backfire (almost a puff of exhaust) when the engine is shut off after riding for a bit.

[MtnEX]

You know... I have never messed with the advanced key... but...

If you took the top end apart after installing the advance key, and you set the cam timing back with the advance key in place... heck that might be an issue... never really thought about that until now.

What the advance key does is slightly rotate the flywheel position which advances when the pulse generator sends and that advances the timing.

The timing mark is on the flywheel, so the mark would be relocated. I have no clue if it is enough to matter though.

[bkb88]

I know that it was insanely hard to get the lines on the cam sprocket to line up parallel to the head. It seemed to want to be off one tooth advanced or retarded on the timing. I think I may have messed up and put the piston slightly lower than TDC when I installed it. I have read that the sprocket needs to be slightly advanced to compensate for the cam tensioner so that when it is installed, it will put the sprocket back in the appropriate position. Has anyone else experienced this issue?

The flywheel should be only rotated maybe 1/8 of an inch or so forward since it is only a +3 key. I will be taking the cover off yet again to try and get this timed 100% correct so I'll know for sure that it is not a variable in my rough 1/4-3/4 throttle issue.

I will keep you posted on the results... Wish me luck!

[CJM]

Originally posted by MtnEX
You know... I have never messed with the advanced key... but...

If you took the top end apart after installing the advance key, and you set the cam timing back with the advance key in place... heck that might be an issue... never really thought about that until now.

What the advance key does is slightly rotate the flywheel position which advances when the pulse generator sends and that advances the timing.

The timing mark is on the flywheel, so the mark would be relocated. I have no clue if it is enough to matter though.

Indeed possible, but many havent had an issue.

Me, I would remove the key and retime the cam and see what happens. it will always look like its retarded slightly due tot he way the whole things designed-dont worry its fine.

[bkb88]

Okay guys here is where I'm at on the timing. I didn't have much time last night so I have just finished looking through the spark plug hole and making 100% sure the piston was at true TDC and making sure the cam sprocket would line up. I don't know if it can get any better than this.

"T" mark on the flywheel is a little farther forward as to be expected when running an advance timing key.

http://i100.photobucket.com/albums/m14/thebutelr/SANY0561.jpg

Cam sprocket lines perfectly horizontal with the top of the head.

http://i100.photobucket.com/albums/m14/thebutelr/SANY0565.jpg

Cam lobes facing down.

http://i100.photobucket.com/albums/m14/thebutelr/SANY0566.jpg

This should be all I should ever have to mess with on timing unless I am completely missing something here. :confused:

[bkb88]

Update:

I finished re-installing everything and fired it up again and it still has the exact same symptoms. The bike will idle fine but when I give it anything past like 1/8 throttle it will not run "cleanly". The rpm's will not stay constant and it seems to sputter in the midrange. I have searched high and low for any cracks on the intake boot, leaks in my exhaust, etc. While taking off my intake boot I noticed something odd. There seems to be a rust colored substance coating the intake ports. I had wiped out the right port for a comparison between the two.

http://i100.photobucket.com/albums/m14/thebutelr/SANY0576.jpg

Is this a sign of bad gas or is this normal?? I have purchased my 93 octane fuel from my local gas station and I don't believe they sell much of the 93 so it could very well be old and full of crud. I am pretty much out of ideas on possible solutions. If anyone has any ideas please let me know.

[MtnEX]

Yeah, that looks like residue from bad gas.

I'd get that fuel out of there.

If the problem still persists....

You are using OEM carb jets right?...

Have you checked the float level?...
The level should show with residue like in the intake ports.

How about the needle?...
Changed positions?... Took it all apart and checked it?

How about the butterfly & slide syncro?....
All you do with that is inspect the carb and verify that the two are moving in sync.

People here have told me this part is crap, but I beg to differ. If your slide and butterfly are not moving in sync when you press the throttle, your quad will run like s#!t on the needle (1/4 - 3/4 throttle).

The reason is obvious... the tapered needle must be raising up out of the needle jet in proper sync with the throttle butterfly opening...

Likewise, if your slide happens to be the part that is delayed in lifting it can even cause you a terrible bog on instant throttle from idle to open throttle. The reason is that the accelerator pump spray will hit the slide instead of spraying through. So point the carb away from you and pump the throttle the first time looking for the accelerator squirt to shoot out the head side.


The instructions on how to set the sync are in the service manual. Page 5-10 or PDF page 74.

[bkb88]

I guess it was a combination of bad gas & rich jetting settings that caused my sputtering. I was able to get it to go away and rev cleanly through the rpm range using the following jetting settings:

-#165 main
-#40 pilot 2 1/2 turns out
-needle on 3rd groove.

I wasn't satisfied with the way my plug was looking after a good hour ride (still looked white towards the end of the porcelain) so I decided to play with the needle yet again. With fresh 93 octane fuel, I lowered the needle to the 4th notch down from the top. The bike seemed to sputter in the 1/4-1/2 throttle range but would clean out and rev all the way through. I then decided to lean out the main jet to a #160 and started to clear up the low end sputter but not completely.

Here is how the new plug looked after the ride today with the following jetting settings:

-#160 main
-40 pilot 2 1/2 turns out
-4th clip on needle

http://i100.photobucket.com/albums/m14/thebutelr/SANY0591.jpg

I guess it didn't have enough time to get color all the way around the plug because here is the backside.

http://i100.photobucket.com/albums/m14/thebutelr/SANY0592.jpg

I am glad to see there is finally color on my plug. However, I was still experiencing a sputter in the 1/4 throttle range. I am also still seeing a black puff of smoke when I give it a hard rev in neutral. Does this look like I will have to lean out the main to compensate for the current needle setting?

[bkb88]

Any ideas?? I am still getting a snow white color on 3/4 of the plug. The bottom 1/4 ring is black though :confused: . The only time I have had any color that looked like it should was when the needle clip was on the 4th slot.

As of now the bike seems to run pretty good but I am still worried about seeing my plug stay white after a good ride. Could there be an issue with my needle or some other worn out part on my carb??

I do have a mix of stock jets and some aftermarket hex main jets from jetsrus.com. Would these really mess up my jetting so much to make my plug white? :ermm:

I have recently moved the jetting back to a K#170 main, 3rd clip on needle, and a #40 aftermarket pilot. Acceleration felt flat with the K#160 and feels much better with the K#170.

[MtnEX]

What have you done to the bike to have the need for such big main jets?

[bkb88]

I have done the following mods to my bike:

-86mm Wiseco 10:1 piston
-Stage 2 Hotcam
-+3 timing key
-Ground header welds
-HMF Slip-on
-XR400 Head Gasket
-Airbox lid removed

[CJM]

Id say you need a 42 pilot, I tried the 40 and it ran a bit lean on the pilot circuit.

[MtnEX]

Originally posted by bkb88
I have done the following mods to my bike:

-86mm Wiseco 10:1 piston
-Stage 2 Hotcam
-+3 timing key
-Ground header welds
-HMF Slip-on
-XR400 Head Gasket
-Airbox lid removed


Originally posted by CJM
Id say you need a 42 pilot, I tried the 40 and it ran a bit lean on the pilot circuit.

I would agree... try a 42 pilot and adjust the fuel screw until it peaks on idle speed.

Set the needle in the middle

Go up on the main jet until it bogs at full throttle. Then back down until it cleans up.

Then put in a fresh plug and chop.


Myself, I think you are putting a bit much concern into getting the porcelain "colored" well. A lot of that has to do with what is in the fuel and how long you run the plug.


Right now to me your base ring looks plenty fat, but it is important to have all the circuits in harmony and you can't do that without finding the right pair of jets.

I think you are a little lean on the pilot and doing a little compensating for it with the needle and main trying to get it right.

[JOHNDOE83]

I think, the main jet in the 160 - 165 range is right, the needle is whats giving you the dark on one side and light on the other, go back to 3rd notch from top and leave it. I can explain why it looks like that in detail but its a long explaination.

I dont know exactly how your going about your plug run, from my experience "Ive chopped alot of plugs" the plug chop method isnt 100% anyway you do it. But from what I see on your plug, your in a ok spot with minor tunning needed.

I feel like your doing 2 types of plug runs and trying to get the same results from both.

If I were you, 160-165 on main jet "Id go with 165", needle 3rd notch, 40-42 pilot and 2.5 - 3 turns out on the screw depending on which one you go with. You could leave the 170 and not worry, it may look slightly rich on the plug but if it smoothed out the powerband then it may be best, if you were stricktly jetting by the plug, it would be like a 168.

If your still not happy, theres always the go big or go home method, thats what I use....lol.