CRF's Only Forums

I have a 2005 CRF450X. I sent the head in to CRFs Only for a Kibblewhite valve job. While the carb was off the bike, I took it apart and gave it a thorough cleaning.

The bike is now very hard to start and requires using both the button and kickstart at the same time (never had to do this before). It seems to idle fine with the choke on. No matter how long I let it warm up, turning off the choke kills the engine. In neutral with the choke on, the engine sputters at 1/4 throttle, but seems to rev OK.

I went back and checked the valve operation and clearance, timing marks, etc and it all looks good. I disassembled the carb again and blew compressed air through all the jets and passages and reassembled carefully. Bike still does not want to run right.

I did not make any changes other than the valve job and replacing the affected gaskets and fluids. I did not change any jetting. I did not touch the cylinder and piston. I have not done a compression test but there is plenty of resistance when kicking the engine through. I'm using fresh gasoline and a fresh air filter.

It seems like a carburation problem to me. My plan is to go through the carburetor again and pay special attention to the slow circuit. Please let me know if you have any theories about what might be wrong or any recommendations for troubleshooting. Thanks.

Have you verified the Hot Start is not a issue ?(either bound up cable or crud on the brass making it stick in the carb and not seat)

Did you put the slide plate in correctly ?

Something is leaning the mixture , if your getting fuel , if the fuel is fresh , if the float is adjusted properly , and you assembled the carb right , then it should run without the choke

You need to keep looking at the carb as the issue

Replace the pilot jet... and see if that helps.
Oh, and don't use the kickstart and the electric starter at the same time... You can crack your engine case. Also check your De-Comp gap.

JimDirt, you are correct. I went to pull the carb off the bike and noticed the hot start cable dangling freely. I checked the threads on the plastic adaptor on the end and they were pretty well stripped, not good enough to get the the cable to stay in the carb. Looks like I overtightened them or they finally wore out. I will order a replacement and see what happens. Thanks for your input and encouragement.

Glad to help , get this from here , it will solve your issue , i have one on mine

http://www.crfsonly.com/catalog/product ... ts_id/5100

JD, sorry, I'd forgotten about those aftermarket nuts. I already ordered a new cable. At least it was few bucks cheaper than the fancy nut. I figure if I got nine years out of the original, I can probably live with plastic now that I will be more careful with it. The trick is to peel back the rubber the boot when you tighten the nut. The nut spins freely -- less chance of crossthreading and a more accurate feeling on the torque.

No problem , yea i know about the rubber cover , but once you over tighten that plastic one even a little bit , its done , so thats why i went with the metal one , that way you dont have to be as delicate with it

I didn't look at the metal one so much as "fancy" ,but as more durable , since i do a lot of carb removal on mine , i thought of it as a wear item , and going to the metal cuts down on the wear , as well as the need to be delicate with it because when you tighten the metal one you know when your tight enough , with the plastic its real easy to tighten it just a tad too much and thats all it takes to destroy the threads

Either way , as long as it works now !