Jerry,
Believe it or not, the pipe cutter will restore the piston but you can over do it so easy.My cutter has been modified, it has been sharpened to remove the small flat that is on most wheels. This allows for a much lighter groove.
If you elect to do this, do it very carefully and lightly. You will have to break the piston back in slowly but you actually can run the piston a couple of more weekends.
However, you will find that this trick is only good for a short time and will
have to be done again. After the second groove job, I typically scrap the piston.
REMEMBER I SAID:
You can really screw up quick if you are not careful!
Carl,
You can really get after those grooves in a piston if you have a helical lap to bring the piston back to size.[www.helicallap.com]I have a set of 3.5,7.5 and 11CC external laps and have been resizing pistons for years and then re-lapping them to fit the liner.
The re-lap job will last for one hell of a long time.Maybe not as long as a new P&S but dam close to it.
In fact I have a personal piston in a motor that I have done 5 or 6 times and the motor just gets easier to 2 stage.I don't know why,it just does.I suspect it has something to do with reduced drag but I don't really know for sure.
These laps are not cheap and they take some getting used to.Learning what lapping compounds to use is the learning curve.
When you get done wash the piston in the dishwasher with Cascade to get rid of all the laping compound in the aluminum pores.Just put a piece of wire through the wristpin hole and securely wire it on the rack in the dish washer.
The beauty of this process is the piston does't need to be perfect.I have taken siezed pistons.cleaned them up in the lathe with some 600 paper,re-cut the oil rings and then expanded the piston with the cutter and re-lapped it in to fit.The motors run great.
Carl is right,be careful and keep the cutter in the grooves when you are expanding them.
Carl,don't be to quick to go to the trash with those pistons,I'll gladly take them off your hands.
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