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Spark + Gas , but dead bike

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HELP!!!

The bike ran great last fall. I had a 262 kit installed, new timing chain and the valves reshimmed after the riding season, but did not try to start the bike until this spring after I perfomed my winter maintenance. This spring my bike won't start at all.

Spark - I performed a spark test with the plug against a bolt on the engine block. I saw a strong, blue spark using a brand new spark plug. I am using an iCat. My hour meter is advancing as we kick the bike. I assume I would get spark if the kill switch were malfunctioning.

Gas - I put in brand new BP Amoco 93 octane. Nothing. My mechanic removed the carb and sprayed starter fluid directly into the cylinder. He said it should have started and run like a scalded cat, but nothing.

Compression - compression is about 30 pounds after 3 or 4 kicks. I am running a 2003 YZF exhaust cam with decomp.

Timing - The timing was checked and rechecked by the mechanic.

We are absolutely stumped. After we check the valve clearance we are going to start working through the electrical system next. ANY THOUGHTS?

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{Compression - compression is about 30 pounds after 3 or 4 kicks. }???

Are you sure your mechanic installed the piston rings, I would be realy mad if i only had 30 psi.

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compression is about 30 pounds after 3 or 4 kicks. I am running a 2003 YZF exhaust cam with decomp.

The timing was checked and rechecked by the mechanic.

30 pounds of compression with a decomp system active is not than unusual, but it should produce more than 15 on the first kick. Try removing the cam cover and folding a piece of card stock like a match book cover to make a wedge for the flyweight on the exhaust cam. Push the weight out against spring pressure a insert the the paper wedge. It must not fall out of place into the engine, so be careful how you set it up. You can then get a more realistic look at the compression. REMOVE THE PAPER when you're done. :naughty:

You say you checked the timing, did you check the valve timing?

The two things that make the most sense given that it sat for so long are rusty valve seats, or more likely, a blocked orifice in the carb. The fact that it wouldn't run on starting fluid without a carb on the intake doesn't rule out a fuel problem.

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Could it be that the shims are not installed correctly, causing the valves to open a bit?

I'd check to see that they are fitted on there properly.

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i know we all took physics and everyone knows it takes 3 things ta make fire, gas, spark, and air....but since it wouldnt run w/o the carb iono what ta tell ya....maybe the decompression is messed up and havin the valve open a little bit

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I am positive that the piston was installed correctly. I am leaning toward the valves out out spec.

I will report back with results...hopefully the answer.

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Problem Solved

Somehow I managed to snap off the semi-circle shaped Woodruff key that holds the CDI magneto (flywheel and stator). This may have happened when I was replacing the stock water pump impeller with a Boyeson impeller. Since the flywheel was no longer held in place by the Woodruff key, my timing was off and my bike would not start despite the motor being perfect (cam timing, compression, etc.) having gas (carb properly jetted) and spark (perfect blue spark from spark test).

Now if it will only stop snowing I can report on the FM 262 kit I installed last fall! The Yamaha dealer mechanic that fixed the bike said it rips, and I should go down 2 or 3 teeth on the back sprocket because it runs through the powerband too quickly.

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