mrb_it400

I have a 1978 motor in my It 400. I've been searching the internet without much success, how to check if the reed valve is operating properly. Does any one have experience in this field?

The bike is harder to start when cold, often starts better cold without the choke on, usually starts well warmed up. The best way I can describe what the engine is doing is: decent power on take off, as rpm's reach mid range it begins to sputter (surge yes) almost like a rev limiter.. if I stay in the throttle the rpm's gradually increase with little or no gain in power.

thanks for the reply blackhat250. The bike is harder to start when cold, often starts better cold without the choke on, usually starts well warmed up. The best way I can describe what the bike is doing is: decent power on take off, as rpm's get to about mid range the engine starts to sputter (surging yes) almost like a rev limiter.. if I stay in the throttle it will gradually go higher rpm's but limited change in power.

Hey guys, my 1978 it400 has rebuilt carb, top end, & replaced spark plug. Plug wire is in good condition. Hard to start sometimes, other times 1st kick. Plug doesn't look excessively wet (though I'm new to 2 strokes). I tried adjusting the carb main jet needle 1 notch richer, without any change. Suggestions?