60 mm pistons?

[Larry Perkins]

Paul are the 60mm pistons that Carl is speaking of the Ymaha 305 pistons?  If so are you meaning one like them but smaller pin?  Just trying to follow and I am certainly not an engineer.

Larry P

[Paul Danik]

Penton eventually had pistons made up by Weisco that had the same size wrist pin and pin location as the Sachs piston which made the conversion much easier. I think they might have been labeled as Hi-Point at one time as well.

A little bit of info on finding an early conversion at swap meets and such is the fact that many of the early conversions that Penton did, and if I am not mistaken exchange conversions that they sold as well, would have the Sachs hi compression head on them, so...., when you find a cast iron cylinder engine topped by the Sachs hi-compression head, take a good look at the base of the cylinder to see if it has been machined thinner. You can usually tell by how little metal is below the cast in number on the cylinder base vs how much metal is above it. Found a good number of early 152s over the years that way.

I am not sure what pistons Carl has.  

Paul

[Larry Perkins]

Got it! Thanks!  Carl can you check and see if the pin size is the same as a Sachs piston?

Larry P

[Carl Hill]

I will check it out. Stay tuned...

[Carl Hill]

OK, here is what I found. The overall height and contour of the piston is the same as 125 Sachs. The wrist pin is 1mm larger. The distance from the pin to the piston crown in 3mm less. So... Yamaha? Was this a common mod back then?

[Carl Hill]

So I dug out an old Hi Point catalog and it shows the 152 kit for "Mudlark, cafe MX, and 68-69 Penton ". Also lists 2 different wiseco pistons for 152, "old style" and "new style".
With "2 thin compression rings" which my pistons have. So I am thinking now I may have the "old style "  wiseco pistons.