yz400f ?

[Lawrence Olson]

I have a 99yz400f. Bike has been giving me a problem  \. During the last ride towards the end of the ride i notice a loss in power and it was popping ? . Since then i have cleaned the carb and got it running nice no popping. takes a few kicks to start. but still have a no power problem. i know its a four stroke but think of it ths way i have no powerband. Almost like its in limp mode only applys so much power. could this be a cdi issue?

[downonmonday]

When was the last rebuild?

[grayracer513]

Check your cam timing. 

[toten]

+1 on cam timing. Also check valve clearances, they can lead to problems with hot starting.

[Lawrence Olson]

? thanks guys for the replies. it starts just fine when hot. runs and idles great. if your a mechanic think of it as its in limp mode  

.

[Lawrence Olson]

forgot to add one thing a few times i would go to kick it over and it would act as if i had the decomp lever pulled. when i didn't. so i think yo may have something there with a valve problem ?