Compression low, need help diagnosing

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Malama Pono
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Joined: Fri Jul 14, 2017 3:36 am
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Compression low, need help diagnosing

Post by Malama Pono » Fri Jul 14, 2017 4:09 am

Hello, First time on this forum, I have a 2010 SYM DD50,its made in Taiwan and the engine, is a copy of the popular (HONDA DIO ENGINE) It was a rental bike and had alot of miles on it, so I wanted to freshen up the engine. The engine was stock with the restrictions removed and it ran but not impressed, so I did a compression test and it only had 90-psi. So I purchased a new Polini Contessa 72cc kit and installed it correctly, changed the crankshaft seals on both sides, removed the oil pump and sealed it with the aftermarket billet alluminum plug, and installed a new 19mm Keihin carburetor on the factory intake. I then performed another compression test before starting it up and it only read 95-psi with me holding it wide open on the throttle. With that all said, can someone please help me figure out why my compression is still below 120-psi?

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