Any gueses?

johnmarchetta34

johnmarchetta34

Location
Akron, Ohio
kevbo said:
You most likely could get by with cleaning the aluminum off the cylinder walls and install a new piston. Most importantly, make sure the combustion temps are cooler. Start by opening the top screws 3 turns, power should be down. Then slowly close them until response and power is adequate. The idea is to stay slightly rich of peak power, that is a lot rich of peak heat.
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I agree, but since I have everything apart and there is mild scoring on the cylinder, I am going to bore everything 1mm over to be safe.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
fastgtfairlane said:
No need to go 1mm over if .5mm over will do the job. Just extra work with no gain and eliminating possible rebore in the future.
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Ditto don't go any farther O/S than you need to go to clear the scoring and get the cylinder back round, if .25mm will do it then go .25mm .

You have to go several mm's before you realize any performance gains , Yamahas won't bore out that Far.

Send it to whoever is boring the cylinder and let them determine what needs to happen is my best suggestion.
 
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WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
701 will go out 3mm to 84mm which is the stock 760 bore size

32T cylinder has much thicker sleeves than the 61X cylinder does .
 
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