Hi everybody nice site here

i got a question my 300ex will not full throtle in any gear but if full throtle it out of gear it will stay full throtle but not at half it just spits and sputters i.replaced a solenoid on it and ive been reading up and found all kinds of stuff on what it could but i caan not figure it out is there anything that could cause it to that i have cleaned out carb and everything oh yeah and the jets inside of carb does the center jet the main have to b at a certin adjustment or all the way snug

 

The main jet gets screwed in all the way. Is it getting enough air? Is the filter clean? Other than that, I don't know because you say you have cleaned the carb.

 

Welcome to the forums.
I have had 3 EX's and currently have a 96 EX. I love em!

Providing that there is no issue with air going in and out (air filter/air ducting/pipe)::
I'd be looking at the compression. Whether it's a wore piston or valve.
OR VALVE ADJUSTMENT. hehe
But it could be a bent/broke/wore/sticking valve. I find it hard to believe the timing chain slipped a notch.
I consider the valvetrain bulletproof for the most part but being a 91, things wear out.
I'm sorta betting on the piston.
Hope that helps.

P.S. Using periods helps. I understand you know what is being said, but we have to read it a few times to understand.

 

There IS a valve adjustment procedure for the 300ex. Don't remember what the measurement is but I DO KNOW that they need to be adjusted periodically.

 

I stand corrected. Thank you.
I went to look in the parts bin. No valves/rockers but I did find the clymer manual.
It calls for .004 valve clearance.


I also found the EX head I ported for the boy. Took 2nd at the Red Bud national with it.