How to tell a 48cc from a 66cc Motorized Bike Engine?

[premiumbikes]

I have to get some parts for one of my engines and I am just not sure if it is a 48cc or 66cc motor.

The studs are 6mm. The bore is about 45mm or so.

If you can help me identify this engine, that would be great!

Thanks!

 

[CrazyDan]

The stock 66cc and 69cc engines are 47mm bore. Sounds like you have one of those. If you posted at least 1 pic it would help a lot. If looking for pistons we need to know if you have a low pin or high pin setup. If looking for jugs we need to know if its a 38mm or 40mm stroke. There are variables in the china girls.
Btw, welcome to the forum!!!

 

[premiumbikes]

Have a look at the picture. Pardon the condition of the Jug and piston but this is how I acquired it. Getting a cylinder rebuild kit and the opens are the 48cc and 66cc.

 

[JerboaJohn]

possibility you have the little known 60cc cylinder. i see 45mm cylinder kits that have the normal 48cc bolt spacing and think of it as big bore kit. but you'd need calipers to accurately measure the bore.
from the pic we can eliminate 48cc. the bore extends beyond the studs.

 

[premiumbikes]

I think it is a 66cc. I do not have calipers here to get an accurate measurement. Using the only metric tape measure I have.

Maybe my stud sizing is off as well...it is difficult to see a 2mm spread on the ruler.

Either way, my local dealer has 48cc and 66cc rebuild kits. I need to get one at least. Could you assume that maybe 70% chance my engine is a 66cc?

 

[JerboaJohn]

66cc +,, 90% sure since it looks like 8mm studs. it's good you have a local dealer for parts. it's a bummer when you order parts online and accidentally tear a gasket or something

 

[premiumbikes]

You are 100% right. I just remeasured and they are 8mm studs. Thanks!!