Question about 2002 Yamaha YZ 426 F

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Yamaha YZ426 not starting after head gasket repair. bike was starting easy before repair New timing chain new spark plug, everything done by the manual.triple checked before assembling and still get nothing. what could be the problem

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This could be a compression problem, Try Removing spark plug and use a compression gauge

You may not have sealed the head proper and bike is lacking in compression..

Posted on Jul 06, 2010

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Well, the first thing to check is compression.
If the valves are miss-timed that will affect compression.
If the gasket is not seated correctly, that will affect compression.

So compression can tell you a lot.

My first suspicion would be valve timing.
You could possibly have damaged the spark plug wire

Try a little starting fluid. If it starts easily with starting fluid, then the problem is probably associated with the carburetor. (If it has a vacuum-opened fuel petcock, there could be a small hole in that vacuum line, for instance.)

Posted on Jul 06, 2010

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