After rebulding my Vlb 1965 sprint 150 I have been getting low compression while testing engine mounted on a bench vice. I have replaced the rings three times with same results. Also new cylinder and head. Compression is about 60psi I was wondering if I could get more by kicking it instead of using my hand to push kick starter. I do not have carb on so I should get full air flow. The new piston arrow is facing the exhaust port. Rings are gaped to .500mm. What am I missing? Any advice would be appreciated.
I probably wouldn’t worry too much about doing a comp test on a hot engine. I’m going to guess that 90% of all engines out there (car, truck, moto, scooter, boat, tractor) get a comp test when they’re cold. A comp test on a hot engine will give you a more accurate reading on how well everything is sealed while the engine is at its standard operating temp though.
A compression test should be carried out when the engine is at operating temperature. You won`t get a meaningful reading using your method.
That's right. I tested the engine on my Honda Twinstar at 50psi when it was cold. If that was the full compression on the bike it would be blowing smoke and running poorly if it ran at all. But, the bike runs good and strong with no smoke or other problems.
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