No start yz400f

1 reply to this topic
  • RF1

Posted December 30, 2004 - 10:38 AM


I have a 1998 Yamaha YZ 400 that will not start. First The bike stalled out on me in a corner, I was unable to start it. As I was pushing it home I tried to start it after 15 minutes and it fired up. It ran fine I rode it for another 15 minutes got it home washed it and was unable to start it again until the next day. The next weekend the samething happened except that I was not able to start it again.

I checked the air filter ok I cleaned it put a new plug in it. It is getting spark but I did not notice a blue spark at the end like the Clymer manual stated only a yellowish/orange spark but I did not give the bike a full kick I used my arm. Do I need to give it a full kick as if I was starting it?

That is the only things I tried so far, I was going to do a compression test on it but mse does not have an adapter fot the small 10mm spark plug hole, I ordered one from my snap on dealer.

What should I do next? I was thinking I have a problem with the compression release because when the first time the bike stalled out on me and I could not restart it I noticed that I could kick the bike over through its entire range meaning before I had any problems to start the bike I would have kick the lever slowly until it stops, pull in the compression release lever and bump the lever past the hard spot. Return the kick lever to the full upright position, release the compression lever and kick. Now there is now hard spot the kick lever does not stop at the hard spot and I can hear a hissing sound like the compression is escaping.

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  • s3706

Posted December 30, 2004 - 11:21 AM


It sounds like you have a valve that is stuck open. I would pull the valve cover and check each valve to make sure they are within specs. If they are not then re-shim them. If they are in spec then I would perform a leak down test and this will tell you if you have a valve stuck open. Make sure when checking the valves that you have it set on TDC.

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