My Jetting

[sprtrx300ex]

Right now I am running:

DJ needle on 3rd notch
DJ155 mainjet
42 pilot with 2 turns out

Does my pilot sound to lean being only 2 turns out?
What about the mainjet? Its about 70 degrees and I'm at 400ft.

It still pops a little bit, but I think its noraml because of the pipe design.

My mods are:

WB R-4 slip-on
Wb powerfilter

[trailburner]

Sounds pretty dam close to me ...[check your plug] If you want to find out for sure wait to see if "cals400ex" posts some Info for you. He is a carb God............ ;)

[cals400ex]

well trailburner, i am not a carb god, but i rejet mine so much that i do have an idea where my jetting needs to be for the most performance.

are you just having problems with it popping when you are deceleration and not on the gas?? if so, i bet your just a little lean on the fuel skrew. i usaully run about 2.5 to 3 turns out on the fuel skrew. as far as the main and needle go, i can't help since you use dynojets. the popping for sure should not be the mainjet unless its missing on full throttle. i find the stock needle to be too lean in the 3rd positon but too rich in the 4th position. so the fix for that is to get a washer from C&D so you can adjust your needle approximately in the middle of the 3rd and 4th positions.

what you could try is get your bike up to normal temperature and let it idle for a minute or so. this will give you a plug reading from your pilotjet/fuel skrew location. i would bet your pretty close but a little lean on the fuel skrew. i would leave the 42 pilot in. also, don't let your bike idle too long with the 400ex's being air cooled. i actually never tried this method of checking the pilot jet and it may not even work since it is harder and harder to look at the plugs anymore to get a good reading since the additives in the fuel these days. you may always get a little pop here and there with an aftermarket pipe. however, turning the fuel skrew out and richening the needle fixed the popping on deceleration with my bike. good luck

[sprtrx300ex]

I recently had the 42 pilot with 3 turns out on fuel screw. It ran good but still popped a little bit. I went out a little more, but no difference, so I put it away. The next day I tried to start it and it.... nothing. I ended up fouling the plug. The gas was not left on, nor the choke, nor did I pump the throttle. However, I did end up pumping the throttle a little bit when it wasn't starting. I took out the plug...Black and smelled alot like gas.

Pilot:
The next day I took off the card and turned the fuel screw in all the way, then out to turns, and put in a 155 main (not because of the stating problem, but because I suspected that I was a little rich on top end). I put in a new plug and turned the key and it started right up.

Needle:
In the beginnning of my jetting, I have the needle on the 4th notch and the washer on top.(DJ needle). It studders a bit. So I moved it down to the 5th notch. It studdered ALOT. I then put it on the 3rd and it ran great, So I'm thinking that its right-on.

It still pops a little bit on decell, But its not like a POP, POP, POP CRACK, POP.

Its more of a mellow pop(about 4x).

So right now Im not sure I should turn the pilot out anymore because I think I might Foul the PLug, But however its still poping.
There are definitly no exhaust leaks.

So, What do you think? This pipe will always pop? or is there something else that I need to do?

[Doibugu2]

If your lid is on, then your way to rich with a 155.

I'm running a 142 with my HMF slip on and Rico is running a 146, and he has motor mods.

If your stock at 155 your way rich. That is probably why your fouling plugs. You should also have a very bad bog somewhere in your powerband.

just my 2cents.

[sprtrx300ex]

I dont have a bad bog anywhere in the power band. Every once in a while There will be a delayed throttle response, but barley noticeable.

Also, I believe stock is 148, U shouldnt have to go down on the main when adding mods.

[2001400ex]

Instead of making another jetting thread, I'm going to just ask my question in this thread. This is my question...

I have a HMF slip-on exhaust and I have a UNI air filter. I've heard that I am running my mixture too lean because I have my clip on my needle on the very top clip. When I did this (about 3 weeks ago) I thought I did it right, but I am wondering if I should have moved my needle up ONE notch from the stock clip. On the HMF website it says this about the slip-on jetting modifications.

"175 main jet"
"3.5 turns out on air-fuel mixture"
"Raise stock needle to first clip position"

I raised my little clip on my needle all the way to the very top, like it says, unless I'm just a dumb***** and can't follow directions. I've asked this before but I just got confused with someone else when we were trying to establish an answer:p. If someone could tell me if I did the jetting the right way I'd appreciate the answer.

And if I did do it wrong it doesn't matter because about 2 days after I got my exhaust I got a boxer break so I can't ride for no more then 10 minutes. *puts away the soapbox*

[sprtrx300ex]

HMF jetting instructions are the worst.

First of All,

Are you using Dyno Jets or another brand?
Whats your elevation?
Is your lid on or off?



"175 main jet" -- Around 155 is a good place to start
"3.5 turns out on air-fuel mixture" -- 2 1/2 turns out with 40 or 42 pilot
"Raise stock needle to first clip position" -- 3rd from the top

[Doibugu2]

Originally posted by sprtrx300ex
I dont have a bad bog anywhere in the power band. Every once in a while There will be a delayed throttle response, but barley noticeable.

Also, I believe stock is 148, U shouldnt have to go down on the main when adding mods.

That 148 is on the klien jets. The dyno jets are not the same numbering system. The instructsions say on the DJ that you should go to a 146 with an aftermarket exhaust.

[2001400ex]

Originally posted by sprtrx300ex
HMF jetting instructions are the worst.

First of All,

Are you using Dyno Jets or another brand?
Whats your elevation?
Is your lid on or off?



"175 main jet" -- Around 155 is a good place to start
"3.5 turns out on air-fuel mixture" -- 2 1/2 turns out with 40 or 42 pilot
"Raise stock needle to first clip position" -- 3rd from the top

I am using a 165 main Keihen jet (I think I spelled that right?) - that's what Joe at HMF told me, (if I remember his name correctly)
My elevation is quite high, I am guessing maybe 1700 feet above sea level? I live on a mountain...
My lid is on.

This weekend I'll lower my clip down to the third position.

[sprtrx300ex]

OK, your need to try your clip on the 4th notch from the top. If it bogs or studders Then put it on the 3rd notch. The 3rd should be right, but just in case try it on the 4th from the top.

AS far as the mainjet, a 165 is pretty high. Id try a 155 or so and go from there.

You will deffinitly need a 40 or 42 pilot, especially since winter is coming.

Try the the needle and let us now how it goes.

Also

Make sure that there are absolutly NO exhaust leaks. Look for Black soot where the header and slip-on meet. If there is, then you need to buy some exhaust tape (from local automotive store) and put that on. Also listen for "sucking" sounds along the pipe.

[2001400ex]

Where can I order a 40-42 pilot jet from?

I've already checked for exhaust leaks because I had to jockey my exhaust on where the header/exhaust meet. I have the stock exhaust clamp on plus the one HMF gave me.

[sprtrx300ex]

You can get the pilots from your local honda dealer. They will call honda direct and order them for you. The 40 and 42 pilot all together cost me 17 bucks. They will need to look up the size of the 400ex carb in order to get the right size jets.

Some dealers are lazy and say that they cant find the part. If this is the case, let me know and Ill give you thr part #'s

Let me know how it goes

[2001400ex]

Ok, thanks for all your help!:D

[sprtrx300ex]

no problem. Let me know how it goes.

[2001400ex]

Will-do! Like I said, thanks for all your help;)

[cals400ex]

Originally posted by 2001400ex
I am using a 165 main Keihen jet (I think I spelled that right?) - that's what Joe at HMF told me, (if I remember his name correctly)
My elevation is quite high, I am guessing maybe 1700 feet above sea level? I live on a mountain...
My lid is on.

This weekend I'll lower my clip down to the third position.


2001400ex, your rich on the main especially since you are at a higher altitude. the higher altitude you are, the smaller jets you need to use. i am not sure what temp you ride in, but if you are using keihin jets and the only mod is the slip on, the very biggest main i would use would be a keihin 155. in anything but the winter i wouldn't use that big. for the warmer months i would put in a 152. your power will dramatically increase with the smaller jets. i am not even using a 165 in 40 degree weather on my built 406 and i am also at lower altitudes than you.

sprtrx 300ex, i would still turn that skrew out at least 2.5 turns. you mentioned that the plug was wet and black. our carb has an accelerator pump in it so every time you hit the throttle, fuel will squirt out of the carb towards the plug. you mentioned that your bike started right up after taking the carb off. its weird that you mention this because every time i take my carb off and put it back on, it immediately starts up. i don't know if this has something to do with draining the fuel in the carb and it gets refilled when you start it. its weird, but mine does that too. for starting the bike this is what i do: turn the fuel on, put the choke on full and then just hit the start button. if this doesn't work, you may have to bump the throttle 2 or 3 times to get some fuel in there and then just hit the start button without hitting the gas. you may also want to buy a new plug as on old plug will cause starting problems somtimes. also, if you noticed that the popping had decreased when the fuel skrew was out 3 turns, you know you are getting closer to where it needs to be. jetting can be tedious but after doing it over and over, you will get the hang of it pretty quick. i am one of those that tries to get pretty close with the fuel skrew and needle when jetting, but i want the main to be exact because when you are flooring it, the main jet is what counts.

[sprtrx300ex]

OK, Today I'll try 2.5 turns out. Ill tell u if it still pops. I will also do some plug tests for every fuel range.

Thanks a bunch.

[2001400ex]

I'll defenitely order some smaller jets if I will see a larger power increase, thanks alot for your help cals.:)

[sprtrx300ex]

Cal,

I went to the local track today. I tried tuning the screw out 2 1/4, and 2 1/2 turns out. It still pops after being revved high. I also noticed a slight delay in the throttle response at about 1/8 throttle. After I let off the throttle, and then pushed it again , it misses a little bit.

This is what Im thinking:

The pilot & A/F screw is too rich causing the delay in throttle respnse.

Would a rich main jet cause popping?
Thats the only thing I can think off.

[cals400ex]

i can't see a mainjet causing popping unless it is way too big or too small. so is it just popping when you floor it and immediately let off of the throttle?? if you are having a slight delay in the throttle response at 1/8 throttle, i bet money its your needle. since every bike is different, we won't be able to jet it exactly perfect. i noticed that the pilot jet on mine does't seem to do much over anything more than idle. if i give it just enough fuel to cruise around my needle is what is primarily being used. i found this out by:

i was having problems with my headers glowing. this means for one i have stainless steel headers and two i am probally lean. i noticed that at idle or above 3/4 throttle or so they wouldn't glow. but once i hit the gas enough to cruise, even less than 1/8 throttle, they would start glowing again. i messed the the pilot jet. i put in a 45 pilot jet and turned the fuel skrew out as much as 3.5 turns and they would still glow when i gave it enough fuel to go. before doing all of this i was almost positive that it wasn't my pilot jet because they wouldn't glow at idle but just when i cruised around. this made me believe it was my needle. i just moved my clip down on my needle to the 4th position and my headers haven't glowed since. i even leaned out the fuel skrew to 2.75 turns out and this is where i have it right now and the headers don't glow. the thing is, the 4th position is still a little rich for my setup. it is great in the cold months. in the 50 and 60 degree weather i have to remove the airbox lid to help lean the needle out or its too rich. in the summer its too rich even with the lid off but the 3rd position is too lean as my headers will glow. this means i either need a thinner needle or a needle with a different taper. i just ordered a washer from C&D to let me adjust the factory needle in between the 3rd and 4th positions. this, i hope, will be the key. however, with you running the dynojet needle, its near impossible for me to tell if your rich or lean on the needle.

here is how you can tell if your lean:
1. your headers might glow. you might not notice it but at night just check. remember to check when just criusing around too because mine didn't glow when i was riding it hard but just putting around.
2. when you first start your bike and take it for a spin it may hesitate or miss. all you have to do is start the bike ( you can even let it warm up for a minute if that is what you normally do) and drive it in first gear for the first 30 or 40 yards or so. just take it easy and don't give it much throttle. if you feel it miss or hesitate, your probally a little lean on the needle.
3 you can try to do a plug chop after driving between 1/8 throttle and 1/2 throttle. i am not promising you this will work though because the additives in the fuel make it hard to read a plug.

sorry for rambling on about a bunch of crap. jetting is trial and error and you have to stick with it. one reason why my friends with the same bikes can't catch me in drag races is because i am so nit-picky about jetting. it won't make 5 horsepower difference going up or down 2 sizes on the mainjet but it could get you bragging rights on how you have 1/2 of a mile per hour on your buddy. good luck

[cals400ex]

i forgot to mention, make sure your bike is 100% warmed up as that could be the reason why you have a slight miss.

[sprtrx300ex]

Thanks Cal,

I will adjust the needle this wekend. I dont think that my mainjet is far off tho, so it must be the needle. In my Dynojet instruction manual it says that only the pilot causes popping, but I have tried everything I can with it. So Im thinking that you might be right about the neeedle.
The hesitation you described sounds exactly like whats happpening to me. I havent checked the headers but I will.

Once again, Thanks

[cals400ex]

your headers may not glow. its just a possibility. my stock headers didn't seem to glow, but my sparks headers were glowing. that may just because i leaned the jetting out when i put the sparks pipe on. also, i am using stainless steel headers from sparks. yeah, i would try to mess with the needle. if you tried everything on the fuel skrew, it must be something else. by the way, which main are you running?? i think dynojet recommends their 142 or so with just a slip on pipe, but i am not positive since i have never used their jets. however, i don't think the popping is from the main either.

[cals400ex]

i just got to thinking, you have a slip on, right?? did you happen to get a new exhaust gasket? there is suppose to be an exhaust gasket between the header/silencer connection. without this gasket, you may be leaking a little air which could cause some popping. just an idea.

[sprtrx300ex]

I did not buy a new gasket for the exhaust, just the clamp that came with it.

However, I did buy exhaust tape, which DEFFINITLY sealed it up. No leaks.

Thanks for your help, Im gonna go screw with the needle today.

[sprtrx300ex]

Well I went out to mess with the 400 today, and looked at the exhaust and noticed a little bit of black soot where the header and silencer meet. I could have sword that I completely cover the gap up. So im goin to put some sealent on it today. Thanks

[cals400ex]

my friend put some sealant on his and it didn't stay. just warning you. it may work for you though. i think he used some silicone sealant. if it does't work, you can just get a new gasket from the dealer. that should definately work. did you mess with the needle yet?

[sprtrx300ex]

Im going to try to seal up the leak first, then if that doesn't work, then I'll adjust the needle.

[hondarider2006]

yeah tell us what happens when you mess with the needle....I am running a stock piolet jet, with the air mixture screw out 3 1/2 turns, and its winter out right now, so the temp is like in the mid 20's-30's. I was thinking about putting in a 42 piolet and messing with my mixture screw, cause when I slowly give mine gas, it kinda "misses" and than cacthes and picks up. It also pops quite a bit when I run WFO and than let off. I am thinking about putting my clip on the 4th notch...but I would like to see what it does to your bike before I tear mine all apart and find out it still does it....Good luck and keep us informed!

[cals400ex]

Originally posted by hondarider2006
yeah tell us what happens when you mess with the needle....I am running a stock piolet jet, with the air mixture screw out 3 1/2 turns, and its winter out right now, so the temp is like in the mid 20's-30's. I was thinking about putting in a 42 piolet and messing with my mixture screw, cause when I slowly give mine gas, it kinda "misses" and than cacthes and picks up. It also pops quite a bit when I run WFO and than let off. I am thinking about putting my clip on the 4th notch...but I would like to see what it does to your bike before I tear mine all apart and find out it still does it....Good luck and keep us informed!

if yours misses when the bike is cold and your only giving it a little bit of gas, moving the clip to the 4th position will fix your problem.
a 42 pilot couldn't hurt either.
what main jet are you running?

[hondarider2006]

i am running a 165 main, i am gonna lower my clip tomorrow

[2001400ex]

Well I just lowered my clip down to the third position on my needle, I'm still running the 165 main jet, I haven't been able to get a 155 main jet or the other 42 pilot jet. After I re-assembled everything and got the plastics back on, I started 'er up and it seemed normal, I gave it a few pumps of gas to get some gas flowing thru the carb. and it took about 5 tries to start it, I forgot to turn on the gas the first two times I tried to start it.:p After it was started i went to give it a few pumps of gas and it stalled and cut out, I don't know why? It used to do that before I lowered the clip to the third position. I choked it at the higher RPM's and it would rev good, but not great. If I left it choked during the lower RPM's it would stall, like it did before, and I noticed for about the first 15-20 seconds when I would rev it it blew out a white/grey smoke. Anything I did wrong? Or is this all normal? I didn't get a chance to ride it for a few minutes because I just finished at like 8:00, it's too late out for that loud thing to be ripping around, I only took it to the end of the yard and ended up missing my shift:rolleyes: figures...damn broken hand.:rolleyes:

[hondarider2006]

Originally posted by cals400ex
if yours misses when the bike is cold and your only giving it a little bit of gas, moving the clip to the 4th position will fix your problem.
a 42 pilot couldn't hurt either.
what main jet are you running?

Well I moved it down to the 4th notched tonight....now it runs like *****!!! I think that 3rd was a lot better, cause it misses at 1/8 throttle, and at half, and it won't even idle. Do I need to turn my mixture screw out? Or would I just be better off leaving it at the 3rd notch? It was 11:00pm and about 20-25 degree's when I tested it. I am also about 400ft above sea lvl, if this helps anyone that will help me....Thanks in advance -Nick-

[trailburner]

The mixture screw only fuels the motor at idle. All motors are alittle different, mine was doing the same thing when i bought it as yours[missed at 1\8 to 1/2] I was on the 3 notch moved to 4 & it got worse......so I put mine on the 2 notch & it fixed it.....
Good luck....... :)

[hondarider2006]

Originally posted by trailburner
The mixture screw only fuels the motor at idle. All motors are alittle different, mine was doing the same thing when i bought it as yours[missed at 1\8 to 1/2] I was on the 3 notch moved to 4 & it got worse......so I put mine on the 2 notch & it fixed it.....
Good luck....... :)

Alright I am think I am just gonna leave it on the 3rd notch...It seems to run good enough for me there....and I think that the 2nd will be to lean for the winter months...

[pineway]

I figured by reading this thead im a running lean, but when im in 4-5th gear decelerating and off the gas, my exhaust pops a lot. what needs to be adjusted to stop this?

[cals400ex]

i am really sorry hondarider and trailburner, i thought both of you two were using the stock needle. i don't use dynojets so i don't know how there needle is. i feel bad telling you to adjust your needle and me not knowing you are using jets kits. sorry, i am only familiar with keihin jets.


2001400ex, what mods do you have done?? are you using the factory keihin needle or a jet kit needle?? if you are using the factory needle, there is no reason why the needle should be in the 2nd position on the factory keihin needle. the stock position on the needle is the 3rd and it is suppose to be a tad lean from factory. by the way, when you say 2nd you mean the second position from the top of the needle right? you aren't counting from the bottom are you? the top positon on the needle is the leanest and the bottom of the needle is the richest.


pineway, what mods do you have? what jetting are you running? dynojets or keihin? what temp you ride in?

[cals400ex]

sorry, i seem to be getting confused what mods everyone has and what setup they have etc. if anyone has any questions, i am more than happy to try my best to help you out. go ahead and pm me and i will try to help you out. i just don't want to tell anymore people the wrong thing to do because i forgot what jets they use or some other small thing i forgot. sorry for going through the hassle.

[trailburner]

"Cals400ex" you have nothing to be sorry about!!!! It's inpossible for you to know everybodys mods.....you are allways on here giving your "Time & Help" & I for one Thank you!!!!!

[2001400ex]

Originally posted by cals400ex
2001400ex, what mods do you have done?? are you using the factory keihin needle or a jet kit needle?? if you are using the factory needle, there is no reason why the needle should be in the 2nd position on the factory keihin needle. the stock position on the needle is the 3rd and it is suppose to be a tad lean from factory. by the way, when you say 2nd you mean the second position from the top of the needle right? you aren't counting from the bottom are you? the top positon on the needle is the leanest and the bottom of the needle is the richest.

I have only the mods listed in my signature, I have my airbox lid on, my HMF slip-on, a UNI air filter, my holeshot tires, and that's it. I'm using the needle that came with my quad, which I'm assuming is stock. I bought my 400 used from a local dealer down the road. I put my clip down to the third position from the top. Thank you for all your help!

[hondarider2006]

Originally posted by cals400ex
i am really sorry hondarider and trailburner, i thought both of you two were using the stock needle. i don't use dynojets so i don't know how there needle is. i feel bad telling you to adjust your needle and me not knowing you are using jets kits. sorry, i am only familiar with keihin jets.

Hey man don't worry about it. You have nothing to be sorry about. When I did lower my needle down to the 4th, after running WFO and I left off, it didn't pop anymore, so in one way you were right:blah: Thanks for the info though!

[pineway]

cals400ex,

I am running a dj 114 main jet, 2 1/2 turns on the mixture screw, and i am using the dynojet needle set on the 4th notch. I have a sparks exhuast, k and n filter for my only engine mods. The temp is around 25-40 degrees. Thanks for any help.

[rap169]

i hate jetting. ITs a pain in the ***** to be pulling the carb apart 100 times to get it right. My latest problem is with a 400ex carb on my modded 250x. It seems under low rpm i get a bog. but high rpm is great. I also get alot of poping on deceleration, and it coughs when im running high rpm and come almist to a stop to go around a puddle, it coughs and sometimes will stall. I am really lost on what i should do next. I have the stock slow jet, but am using dj main and needle. Not sure on the numbers right now. I think its a 165 and clip on need is in the middle. Any ideas?

[cals400ex]

pineway, it will be hard to me to tell. i don't know what to tell you on the dynojets, since i have never used them. also, i have never jetted a 300ex. read farther down this post for my suggestions.

rap, it is possible that you may lose lowend and gain up top with a bigger carb. the hesitating and stalling should not happen though. a 165 seems too big for a 250x motor.

here are my suggestions for both of you:
take your bike out and warm it up to normal temp. this make take a little while if it is cold. after you do this, let your bike IDLE for about a minute. don't give it any gas, just idle. we don't want to let it idle to long since both of these bikes are aircooled. shut it off and check the plug. take note on what color it is. put the plug back in and take the bike out and run it at about 1/2 throttle or so in 4th or 5th gear. pull in the clutch and shut it off. check the plug again. just remember to not let it idle or don't go up to 3/4 throttle when doing this test. take note on the color of the plug. put the plug back in and take the bike out and floor it. make sure your floor it long enough to get to top speed. at this time, pull in the clutch and shut it off quickly. check the plug again. take note on the color. remember, the engine and plug will be hot when removing the plug so be careful. you will probally notice a nice difference in the color of the plug between these 3 tests. post your results on all 3 tests and then i will try to help. note how the plug color changes, if it does, on each test.

this tests works great for the pump fuel i get here. i know that when i use shell fuel i need to run for longer distances. i guess the shell may burn cleaner or something and does't give a plug reading as quick. also, i have best luck when using the plug you have in your bike now. i wouldn't put a new plug in when doing this test. let me know how it goes.

[exrider3000]

whats it cost to jet a 300ex

[2001400ex]

$5 if you get a jet from HMF, they're keihens, not sure if they make them for 300EXs though. www.hmfengineering.com

[exrider3000]

thanks man:D

[2001400ex]

No prob. dude:D

[hondarider2006]

damn this turned into a long thread....lol:cool:

[cals400ex]

Originally posted by 2001400ex
$5 if you get a jet from HMF, they're keihens, not sure if they make them for 300EXs though. www.hmfengineering.com


thats assuming you buy the right one you need. lol if not, you will be buying a few. i actually have every keihin one between 150 and 165. jetting changes so much throughout the year, i wouldn't be able to use the same one year round since i am so particular about jetting

[2001400ex]

True, I'm thinking about doing what you've done, I still need to get the 42 pilot jet.:p