hi guys im New to the forum and wondering if you can help me out!

07' klx250s with OEM 300cc kit, Two Bros M7, and twin air filter
#35 pilot, #128 main, N1TC needle middle clip position

I was riding after warming bike up for a few minutes and all of a sudden while riding it sputtered as if out of gas and it wouldn't stay running at idle unless you gave it gas, so i cleaned the carb and set the fuel/air to 2.5 turns out. It runs a little better but always sputters and dies randomly at idle and has jumpy idle when adjusting it.

plug is whitish on the electrode and spark seems a tad weak, lean conditions or valves out of adjustment?

 

How old is the plug ?

I would replace that first and see how it goes.

 

I've owned the bike for a month so not sure how long the previous owner had it on, but its not crazy black or anything so idk if its fouled but i will replace it tomorrow and see if there is any change in the running condition

 

I'm running the 132 and 40 jets, In 12,000 miles I haven't even had a hickup, my bike runs flawlessly. How many miles on the bike? Oh and welcome to the forums man!!!

 

check for pinched vent hoses on the carb. Seems I recall an earlier post where the vents got pinched during a carb re-install. Fresh gas? Can you adjust the fuel screw with the carb in place, running, and see if it makes any difference in idle speed?

 

When you cleaned the carb, did you remove the pilot jet and inspect it? The hole in it is very small and it doesn't take much to restrict gas flow through it. The pilot jet runs in parallel with the idle mixture screw (fuel/air screw). This will affect idle to around 1/4 throttle.

If the engine runs good at upper rpms and under a load, the problem is most likely not electrical.

When you get time, check the intake valve clearances. They have a tendency to close up with use.

Let us know what you find.

Ride on
Brewster

 

what elevation are you at? the bike only has around 3000 with only about 1000 on the 300cc kit

 

Yes i cleaned with carb cleaner then blew everything out with compressed air! It seems to run fine after about 1/4 throttle (before that it still sputters), the idle hangs a bit though, i tried putting in a 130 main and the clip at the middle position to richen it a bit and it didn't seem to help

 

That's a good sign though, as those measures shouldn't really do anything for the idle (<1/4 throttle) circuit. You may want to pull the pilot jet out again and carefully inspect it. There could be a chunk of something still stuck in there, even after cleaning.

Hey carb experts...how about float level? Could a mis-adjusted float cause a problem at idle, but not at wider throttle openings?

 

I am with IDRIDR, check for a pinched or burnt vacuum line.

I had the same problem with my bike. One day it just started having problems idleing, ended up burning shut a vacuum line. Fixed it and ran like a champ.

Hopefully it is something simple like that