50cc to 80cc conversion...

[Steve Best]

So much to do and so little time to do it.
This is the cylinder and head in the orientation they go on the scooter.
Scooter uses a fan to blow the air crosswise:

I like that is says 49cc on the cylinder.
This is how I'd be running it on my bike:

The cylinder offset is due to tuning it 90 degrees. This is how it will bolt up. Large 1" exhaust instead of the 3/4" on the China Girl.

Combustion chamber is fair, lots of transfer port area:

Lots of cylinder port window area:

Steve

 

[Chevynova410]

What is the name of that cylinder and where do you get it? What about the big hole is that the intake side?

 

[zippinaround]

nice found it! haha man that looks like a mean cylinder!

 

[Steve Best]

This is a cast iron 49cc Minarelli vertical cylinder made for 50cc scooters. Reed valved and making about 5hp, it will almost fit on our China Girls with a little adaptation. This cylinder is absolutely stock, but there is an aftermarket for these. The Minarelli horizontal engine has a 50mm bolt pattern and would take some work to adapt.

 

[LRSimons]

Very cool! Is there a coating on the cylinder? I'd imagine that with a harder metal it wouldn't be as necessary. Looks to be a machined finish from the picture.

It would be great to have a china girl made from iron/steel instead of pop cans and crappy chrome coating. It's not like it's going to weigh much either way. You've got me thinking again about machining one out of steel...

Hope the case threads don't rip themselves out from the torque keeping that beast together!


Logan