- Location
- Round Rock, TX
Ok I'm in the middle of a top end rebuild on a 2002 Honda CR125R. The bike is not mine but a friends so the details might not be 100% accurate.
This was about 1.5 years ago. He installed a Wiseco 54mm piston kit and adjusted the ring gap. With this top end kit he was running 150psi and it ran good. He thought if he went with an OEM piston (might have been prox) and OEM honda ring then the compression would go up to about 180psi. Well after he did that setup it was running 105psi and horrible. After that he gave up and bought a RM250.
Now fast-forward to current day he wants to sell the bike but doesn't have time to do the rebuild so that is where I come in. He gave me the old wiseco kit and the current piston. The Wiseco had a ring gap of .016 and the Prox/honda ring had .021. With the formula Wiseco gives his ring gap was double the size it should have been. With my math the ring gap on the new wiseco kit should be .008. 54mm/25.4= 2.125*.004= .0085.
When installing the new Wiseco piston kit I should have the ring gap at .0085. I told him this and I know he thinks this is way too tight. I'm not sure if he isn't converting the metric or if he is going off the OEM ring specs of .016-.022
This was about 1.5 years ago. He installed a Wiseco 54mm piston kit and adjusted the ring gap. With this top end kit he was running 150psi and it ran good. He thought if he went with an OEM piston (might have been prox) and OEM honda ring then the compression would go up to about 180psi. Well after he did that setup it was running 105psi and horrible. After that he gave up and bought a RM250.
Now fast-forward to current day he wants to sell the bike but doesn't have time to do the rebuild so that is where I come in. He gave me the old wiseco kit and the current piston. The Wiseco had a ring gap of .016 and the Prox/honda ring had .021. With the formula Wiseco gives his ring gap was double the size it should have been. With my math the ring gap on the new wiseco kit should be .008. 54mm/25.4= 2.125*.004= .0085.
When installing the new Wiseco piston kit I should have the ring gap at .0085. I told him this and I know he thinks this is way too tight. I'm not sure if he isn't converting the metric or if he is going off the OEM ring specs of .016-.022