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I have not tried the valves but apparently this may be the issue. I will try and see what happens! Thanks!!
 

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Found defective rectifier/regulator that was producing 16.7 volts. Assumed this was the problem. Ordered a new rectifier from Rick's Motorsports as recommended. Checked the output voltage at the new rectifier, incoming was 23-24 volts from the engine (yellow wires) and 14.4 volts to the charging system (at the battery). Also ordered and replaced the petcock with a Yamaha model with no vacuum line as recommended. Cleaned the tank while I was at it. No change. Starts instantly. idles perfectly. Spits and sputters and will not run smoothly under load. I fear a weak valve spring, bent valve or worse. Engine doesn't smoke but the spark plug carbons up after test running. Still need to verify valve clearances but they are quiet and not chattering. Tested compression again with oil coating the cylinder and it made no difference. This is a tough one!
 

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Running stock size jets? The carb kit I got for my quadrunner came with larger than stock jets, so needless to say I didn't use them.... If you installed a carb kit and didn't check hey sizes, you may be running extra rich, which explains the carbon fouling.
 
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