I went from a 145 main needle on 3 to a 142 and left the needle. Now when you gas it it kinda bogs then surges, but it wont redline. Wouldnt the 142 helped lean it out? It seemed rich to begin with.

 

No one!! Ill go mess with it then.

 

What problem are you trying to solve by going down to a 142 ?

Going down on the main will lean things out when you are WOT. If you're already good at WOT then you may not need to go down, you may just have to mess with the needle or else pilot/idle circuit.

The surge could be a lean surge...not good.

Watch the plugs and piston wash......

What do the plugs look like after a WOT run ?


-jeff b.

 

rule of thumb on jetting. if your asking for throttle and it acts up, your lean. if your not asking for throttle and it acts up, your rich. i wrestled with my 250ex for days over this. are you sure your not redlining and hitting the rev limiter? rejetting will get you there (rev limiter) much faster than stock and it takes some getting use to. a good symptom of running rich is if sounds like its loading up or flooding on idle, the pipe will give off a black, almost wet smoke.

 

bartojc, the 145 is a stock jet, which is very rich. Its not the rev limiter, ive heard that before and know what it sounds like. It like when you punch it there is nothing for power from 1/2 to WOT.

 

voodoo on the Dynojet troubleshooting Guide says 1) check you float level, mine is 7/10 of a inch or 44.8/64 of a inch. 2) It says lower the needle down.( you would think the needle should go up) 3)if that don't work, then it says put even a smaller jet in.
It's worth a try.

 

Voodoo- I am sure you already know this but start over with a new plug and clean the air cleaner. A fouled plug will make you think you are having carb problems. If you are still rich, take your airbox lid off and ride it. If it gets better you are rich and need to go to smaller main jet. With your airbox back on and it starts to cut out at mid to WOT, turn on your choke and see what happens, if it runs better choked , it is too lean.


Jetting can be a P.I.T.A.

 

Thanks for all the replys. The main reason for doing this is for education. I put the 145 back in and its fine. Didnt think 145 to 142 would make that much of a difference.

OBD, i know what you mean. But i got nothing else to do on the weekend hehe.