440ex jetting help

[Nate105]

hey
I have been rejetting my wheeler because I found that I was lean on the main jet by reading the plug. right now i'm at 168 main and I just started getting a light brown color in the plug but the problem is. now that I'm at 168 main in 1 and 2 gear fine no problems but from 3,4, and 5 gear if the rpms are low and I got to full throttle it will sputter like i'm rich for a few seconds and clear itself out most of the time sometimes I have to let off and go again. I need to go up to a 172 main and I think I will be good there but I know if I put that in it will get worse. do you guys have any ideas why it would be sputtering when the plug says i'm a little lean yet please help

[CJM]

Got the airbox lid on, if so take it off throw in the 172 and your good to go.

[Nate105]

ok is it better to run with lid off? now with the lid off I will probably have to go up to a 175 right cause it will make it leaner taking the lid off? and just a question if I wanted to leave the lid on then what would I have to do.

[JOHNDOE83]

If your trying to jett for main jet and not cutting the threads off your plug to check for main jet, your not seeing main jet on your plug.

From your description above, its not your main jet where you have a problem.

www.jetsrus.com read the FAQs section on jetting.

It sounds like your lean on your pilot or needle.

If you wanna jett for main jet, youll need a few more jets in very large sizes to what you have now.

You need to start very large on jets untill it sputters on top end and doesnt rev out fully, then back down sizes in incriments of 5 till it stops sputtering and fully revs out.

Plug reading without cutting off the threads on the plug is useless.

Thats why its called a plug chop.

[Stickman400]

You've posted that method about the main quite a few times but I tried it with no luck. With the mods in my sig. I stuck in a 220 main and it still didn't sputter or anything. And since they only make a 230 main as the next largest size I highly doubt it would make any sense to try it, since that's what people with highly modded 440s are running. So idk if that method works all the time.

[Nate105]

If I was lean on the pilot or needle then why does it only do it when I go up on the main jet? If I went down to were I was for main it runs great with no sputtering but then i'm lean.

[Wheelie]

Sputtering in the upper RPM's in higher gears means you're too rich on the main circuit.

Don't put too much into plug reading. Tune by how the machine actually runs and use the plug as a reference. Tuning by the plug only will cause nothing but problems and tail chasing IMO.

[JOHNDOE83]

Originally posted by Stickman400
You've posted that method about the main quite a few times but I tried it with no luck. With the mods in my sig. I stuck in a 220 main and it still didn't sputter or anything. And since they only make a 230 main as the next largest size I highly doubt it would make any sense to try it, since that's what people with highly modded 440s are running. So idk if that method works all the time.

Here is the method direct from jetsrus. http://www.jetsrus.com/FAQs/FAQ_rejetting_101_how_to_rejet.htm

I understand you concern, with kibblewhite valves and a 450r carb along with compression and bore sizing, even a stock bore could possibly run up to a 220 main jet.

I did exactly what you said, I went and did use a 230 main jet an thats where my sputter is so I backed down to 220.

You can get and use bigger jets, you have to buy minkuni jets which even tho look different will work just fine on a kehin carb.

You could always drill bigger like Wheelie had to do for his e85 setup.

[JOHNDOE83]

Originally posted by Wheelie
Sputtering in the upper RPM's in higher gears means you're too rich on the main circuit.

Don't put too much into plug reading. Tune by how the machine actually runs and use the plug as a reference. Tuning by the plug only will cause nothing but problems and tail chasing IMO.

I think he meant when at low rpm in higher gears he cracks the throttle open and thats when it sputters and takes off. I think he may have confused a sputter with a bog, without being there we cant tell unfortunatly.

Which generally would mean lean, but any motor in high gear at low rpm then WOT might do the same thing.

I totally agree with you about plug reading, with gas now a days its pointless to read plugs.

The sputter will be like a rev limiter only it will have loss of power.

[JOHNDOE83]

Originally posted by Nate105
If I was lean on the pilot or needle then why does it only do it when I go up on the main jet? If I went down to were I was for main it runs great with no sputtering but then i'm lean.

If the main was to rich it would only sputter at wot, it will not do it at any other point in the rpm range.

[Nate105]

(The sputter will be like a rev limiter only it will have loss of power.) quote from johndoe83.
This is what its doing its like i'm on the rev limiter. then after a few seconds it clears. so that would mean i'm running rich on the needle or pilot right?

[JOHNDOE83]

its possible it could be the needle, 3rd notch is the standard placement for ex's to run right, you might be running into a rich spot at the transition from needle to main jet in the rpm range.

you probally need to raise the clip on the needle one notch and test it to see, whats odd about this is you could be to lean on main and you could also be hitting a lean spot in that transition.

Its just to hard to say without being there or without quality video.

the pilot seems to be fine as long as your not poping and backfiring on decel and starts fairly easy.

[Nate105]

yea it start real good and no backfiring the only time it backfires is when I run out of gas. I took it for a ride yesterday and ran it like it was for about an hour then I took the air box top off and it made it alot better. so what would be the problem the needle?

[Nate105]

if it runs better with the top off should I just get and outerwear cover and leave the needle alone. what do you guys think?