Thread: Piston Sizing question
05-16-2010, 10:52 PM #1
Piston Sizing question
The Ski I purchased had a goofed up Mag cylinder and the other two are punched to 1.00 as stamped on the pistons. I purchased a parts ski that has a bad PTO cylinder, and all the pistons are stamped W7A, which I have read mean standard. If I put a standard cylinder and standard piton in the mix with my 1.00 pistons, am I asking for a catastrophe?
05-16-2010, 11:00 PM #2
I've done worse.
Have you found what took the cylinder down in the first place?
05-16-2010, 11:17 PM #3
He burned the piston due to the old fuel pump going bad. He changed out the pump and changed over to the mix. He just honed out the cylinder and stuck in a standard sized piston. It just slapped it silly.
05-17-2010, 09:00 PM #4
05-17-2010, 09:27 PM #5
- Join Date
- Jul 2007
- near Toronto, Canada
That said, I wouldn't worry about it. It's a Fuji 750 engine, and you are not dealing with big power or RPM.
Some guys really prefer to balance all three cylinders with the same overbore. Others seem to get away with mixing and matching whatever.
The only part of the engine that is really going to care would be the crankshaft. You might have a little more vibration than if all three pistons were balanced weights, but I doubt it will be an issue.
If the connecting rod big end bearing is good, and has not accumulated any metal debris from the prior piston failure, I would say just run it with whatever piston + cylinder you can find in good condition.
05-17-2010, 10:53 PM #6
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