New Top End Bike Has issues starting/idling

Hey guys I just did a brand new top end on my 08' crf450r and I can get it to start but I have to hold the throttle partially open for it to start. And when I got it to start it had a hard time idling until I turned the idle screw up. Also, whenever I would blip the throttle when it's started it would stick in the higher rpm range for a little while and gradually slow down to a slower rpm. Please let me know if you guys have any idea of what's going on. I messed with the accelerator pump a little while I had the bike apart so that when I got on the throttle hard it wouldn't hiccup like it used to. I didn't do a big adjustment but maybe that's what is causing these issues. 

Edited by Bigtyme07

Your carb needs cleaning.

Ya check the pilot jet for cleaning. They can gum up fast if you dont drain the gas.

Best just to replace the pilot jet when you clean the carb

 As mentioned above:

- replace (don't clean) pilot jet, and possible  clean the passage above it with fishing line

- put on a fresh fuel screw oring

- set you fuel screw at 1 turn out.

- drop the idle as low as it will go

- now raise the idle with the fuel screw.

We redid the valves on my brothers bike a couple weeks ago and this same thing happened. I read on here that its most likely a clogged pilot jet. Turns out that he was somehow missing his fuel mixture screw on bottom of carb. Replaced this and seems to be fine.

Now I just rebuilt the top end on my 07 and can't get it to even kick over!!

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now