powroll pistons

[Carman24]

Any idea about comp. ratio? They are 65mm pistons

 

[joe p]

It looks more than 10.5:1 to me.

 

[dirtdigger]

Yeah those are about 12.5 to 1. These are my 10.25 to 1 Wiseco pistons, 65mm

 

[Carman24]

Did I read right about 78 heads having larger combustion chambers?

 

[joe p]

Yeah those are about 12.5 to 1. View attachment 1709 These are my 10.25 to 1 Wiseco pistons, 65mm

Ohhh!!! I love shiny things!

 

[dirtdigger]

The difference in the chambers comes in the cb750f2 motors which are larger and have slightly bigger valves. But that chamber would only get you down into the 11's as far as compression. You would have to do some measuring but there are different thickness base gaskets, head gaskets, and you could do some work with the chamber to help lower compression. I think you could get the compression down with enough work and measuring.


I will have pictures of my shiny new 70mm pistons and cylinder once they get in

 

[cyclebuster]

oh man i wonder what my 10041 number pistons are? I do not want to b uild a 12.5:1 engine, there is no gas that will run in it, and the starter wont turn it

 

[Carman24]

I would like to find out what they are. Does anyone have an old catalog in their collection?

 

[dirtdigger]

I cant find any real definite information on these things, they are a cheaper cast piston and it seems noone kept any info on them. I am still looking for more info.

 

[dirtdigger]

hey cyclebuster can you post a picture of yours for reference to compare to the ones above?

 

[cyclebuster]

I will post one asap.

 

[dirtdigger]

I am interested to see what the difference is.

 

[cyclebuster]

this is the 10041 Powroll piston. its brand new, but been setting on the shelf since. this cylinder has been bored, and decked for some reason, i may not use it. I am still looking for the darn rings they were here new in the box. otherwise i am gonna make a coffee table with them. these domes are pretty significant compared to stock

 

[dirtdigger]

I wonder if those are 10 1/2 piston for a F2 head. They dont look like 12 1/2 but its hard to tell. They look a little smaller then Carman24 pistons. Do you have any stock 750 rings, the reason I ask is to determine what the width of the rings are. I know Total Seal can make a special set of rings if you give them the dimensions.