250R jetting help

[XANDADA]

Made the following change and now my R runs like crap :mad: -

I removed the aluminum air box (with outerwears cover on top) and installed the oem plastic with snorkle & EHS modified outerwears lid. I also changed from a K&N filter to a foam filter. I figured that jetting shouldn't really change at all but I guess I was wrong. The engine runs great in 1-2 gear but the top of 3rd gear when it hits the powerband starts to stumble and sound like it is misfiring (not really bogging but missing). 4th -6th gear is all bad from 1/4 throttle to full throttle. Almost acts too lean, what do you guys think? Go richer on main jet and see what happens? I can't beleive I would be getting more air with this setup to create a lean condition. Thanks for any suggestions...

I'm using a 38tmx carb

your not lean the motor is blubbering, god down 3 sizes on the jet.

if you tell me what jet your running I will tell you exactly where to go.

have you checked the plug?

get back to me on your main.

[dariusld]

Have you checked your plug lately, maybe you need to change it.

[XANDADA]

390

[AndrewRRR]

Easiest way to check is just put in a new (properly gapped) plug, ride around for a few minutes to give it a little color, then do a plug chop. I wouldn't think going back to a stock airbox and snorkel would give you more air, so chances are you are just running fat.

[XANDADA]

plug color is light tan with a slight red tint (maybe from red maxima oil?). 1-2 gear runs great, 3-6 gear runs like crap (no power and sounds like it is miss firing with almost a slight cracking noise) at anything over 1/4 throttle. Too lean right? I'm running a 390 main, should I give a 400 a try?

[AndrewRRR]

Yeah, you can't hurt anything by being too rich, lean on the other hand is a different story.

[XANDADA]

Thanks :cool: