odd piston mod

[nander]

I recently seized my motor (I might start a separate thread on the post mortem because I am not entirely sure of the cause(s)) and I set to dismantling another motor I had lying around in the garage to see if there were any salvageable parts I might be able to put into service.It was a Frankenstein motor. Low CB77 engine number, electric start, but a CL cam and a rough homemade plate to replace the CB tach drive. The spark advance was brazed open. Whoever had put it together stacked two base gaskets. Broken fins everywhere. However, the motor wasn't seized and when I pulled it apart, it had two 3mm over pistons that someone must have put on a lathe and grooved. They seem to be ok, other than the odd grooves, and I'm thinking of putting a motor together with them. Please take a look at the photo and tell me what you think.

Anyway, my questions are:

1. Has anyone ever seen a piston like this where someone cut grooves in the skirt?
2. Is it a good idea to run these pistons with some new rings?

Thanks,
nander

[LOUD MOUSE]

YA have someones idea of a racing/competition engine.
The skirts have been shortened also.
IMO I wouldn't use them in a street engine. .............lm

I recently seized my motor (I might start a separate thread on the post mortem because I am not entirely sure of the cause(s)) and I set to dismantling another motor I had lying around in the garage to see if there were any salvageable parts I might be able to put into service.It was a Frankenstein motor. Low CB77 engine number, electric start, but a CL cam and a rough homemade plate to replace the CB tach drive. The spark advance was brazed open. Whoever had put it together stacked two base gaskets. Broken fins everywhere. However, the motor wasn't seized and when I pulled it apart, it had two 3mm over pistons that someone must have put on a lathe and grooved. They seem to be ok, other than the odd grooves, and I'm thinking of putting a motor together with them. Please take a look at the photo and tell me what you think.

Anyway, my questions are:

1. Has anyone ever seen a piston like this where someone cut grooves in the skirt?
2. Is it a good idea to run these pistons with some new rings?

Thanks,
nander

[jerry]

I wouldnt use them in a race engine. Jerry

[LOUD MOUSE]

Ya would loose power in your engine for sure there Jerry. ..............lm

I wouldnt use them in a race engine. Jerry

[nander]

Haha. Thanks for the input. I guess I'll spend a few bucks and order a new pair of 3mm over pistons.

[kirbb9]

What is the reasoning here? Is the ribs to reduce surface area contact with the cylinder and create less friction?


Brady

[nander]

I guess the idea is to have less friction, but I would think there should be little to no contact anyway if all the clearances are right. My understanding is that the rings are in contact with the sleeve, not the piston skirt.

Maybe the idea was to draw oil up to lubricate and cool the skirt?