JS lightweight pistons for stock rods in 850 balance factor change
- Thread starter hhh
- Start date
- Joined
- Jan 7, 2023
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- 243
I just checked the site again and found the "missing link" with the answer: it will increase the stock balance factor of 52% to approx 58%. I'm actually considering installing them in a 920 that I believe to have the RGM 920 kit with "slightly lighter than stock" pistons, so I'm thinking maybe 59%?
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- Joined
- Jun 30, 2012
- Messages
- 14,900
Isolastics affect engine performance ? The engine must vibrate somewhere in the rev range - the point where it vibrates can be moved - up slightly should be better. A Commando engine with 73% balance factor runs dead smooth at 7000 RPM. Most Commando motors probably remain below 4000 RPM. If the balance factor is slightly higher than normal, it would suit a fast rider better. Lighter pistons usually give better acceleration.
- Joined
- Jan 7, 2023
- Messages
- 243
You've outdone yourself this time. There is no RPM where a Commando motor runs dead smooth. Any discussion of balance factor of a Commando engine can assume to have at least a non-zero probability that it will be mounted in an Isolastic frame and must take the frame into account or it's worthless since the resultant balance factor is entirely dependent on the frame. I know and have known many Commando owners and not one has kept the RPM below 4000 RPM, not even warming up.
