Hard Starting warm and cold

I have a 04 YZ 450. I recently did a top end and added the hot cams and ever since then I cant get the thig too start. Once I get it started it runs great but getting it too start is the hard thing. I have asked some people and they say it could be valve clrearence, timming, bad connection, bad spark plug, or jetting but I dont get it. If once I get it started it runns fine it seems as though it would run shitty if it were any of thoughs. Please help!!!

The '03/'04 FCR carbs are very fussy about idle mixture as relates to starting. The cams might make it worse. What I would try if it were mine would be to run the fuel screw all the way in with the engine cold and shut off. Then back it out between 1 3/4 to 2 full turns. If the pilot jet is big enough, it should be slightly rich this way and start OK cold. Then warm it up and adjust the fuel screw according to these instructions:


I'm assuming you are sure the cam timing is correct.

Is it hard to kick over? Or does it kick fine, but not start? It should have about 80-100lbs cranking compression. Either way we can fix it.

Oh yeah. before you send it in to us, you might want to do a leak down test. I had a personal friend say that his CRF450 was hard to start. He brought it in, and we found that it was loosing 50% compression. It was just tired. We where still able to adjust the decompression for him, so that he could get it started in the mean time, until he could rebuild it.

Hot Cams

Attn: Sean

3025 Justin Dr

Urbandale, IA 50322

Make sure you put a note in the box, with your name address, and phone number too.


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