66cc engine bogging

mony0_3

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I have a new engine that ran better than most out the box, after about 50 mi. it now boggs at higher rpm's and dies. I have changed the plug, carb, coil, magneto and fuel tank. It has over 140 psi. compression and the cylinder looks good. What am I missing?
 

DieselTech

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I have a new engine that ran better than most out the box, after about 50 mi. it now boggs at higher rpm's and dies. I have changed the plug, carb, coil, magneto and fuel tank. It has over 140 psi. compression and the cylinder looks good. What am I missing?
It may be leaning out at high rpms or a lean surge will sound like bogging or bad 4stroking at high rpms.
 

mony0_3

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Ok thanks, but it was the rear engine mount bolts loose. Caused the fuel to suds. They had been re-torqued that's why I over-looked them.
 

Axl Myk

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I had that problem with one bike. The gas cap wasn't venting and created a vacuum in the tank. A small hole drilled in the middle of the gas cap fixed it.
 
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