This is strange....

I just worked on my 06 YZ450F for the past 2 nights....got my suspension back from Pro Circuit, installed new bearings & races for the steering stem, brand new oem plastics & seat, fresh Dunlops, bike looks brand new again. I get out to our riding area & when I go to start it I have almost no compression, feels like my 426 when you had the decompression lever pulled & I hear what sounds like air being forced out the breather..I thought I left a rag in the airbox, I checked & no rag so I keep kicking thinking the auto decom pin is stuck a little & then I get compression...sweet! It fires up with the choke on but sounds raspy & as soon as I switch the choke off, the bike starts popping like crazy, backfires & then dies. I restarted it with the choke again but still the same thing. Humm...maybe my pilot jet is plugged or can the decompression pin stick & cause this to happen? Can it be a stuck valve? This was the first ride of our season since it's so hot here & the bike hasn't been ridden since March but I do drain the tank & carb before putting them up for the summer. I have had ZERO problems with this bike since new. Has this happened to anyone else?

Edited by MX1967
spelling

My guess is that you have two problems: The pilot jet is varnished, and there is rust on one of the valve seats. Fix the carb and get it running. The valve seat will take care of itself in a few minutes time.

My guess is that you have two problems: The pilot jet is varnished, and there is rust on one of the valve seats. Fix the carb and get it running. The valve seat will take care of itself in a few minutes time.

Thanks gray....:excuseme:

Fixed it! Pilot jet was plugged....even after draining the tank & carb back in march. I think I'll keep some fresh gas on hand & fire it up during the summer months just to keep things happy. Compression is back nice & strong too. Looks like my bike doesn't like to sit in the garage 7 months waiting for me to ride it.

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