In my search for parts that might be used to create a "shifter" inframe 4 stroker, I came accross this:Fancy Scooter: Gas Scooters and Electric Scooters Retail and Wholesale
It doesn't say what clutch size it fits, but it must at least work for the 76mm, maybe the 3.25".
I went to David Statons site, and found this one that only fits the little clutch found on the micro 25cc engines:5 to 1 54 mm INSIDE DRIVE Gear Box.: Staton Inc
Having found it, I sent an e-mail asking about wheither the above box could be used on a micro 35cc. David replied a few hours later that it was too tight to fit the larger motor. On a roll, I replied that I thought maybe someone was missing the boat not building a clockwise rotation gearbox, and guess what. He's done it, and said he do up nealry anything if someone wanted to pay for it. Then he sent pictures of a Honda GXh50 and what is maybe a Subaru 35 with a CW rotation and inside drive, perfect for inframe and a clean and simple shifter setup without the extra chain and jackshaft. I asked David why no one knew, and he replied "No one asked".
Although you can't by Staton's stuff cheap, it isn't made in China nor does he have a reputation for parts failure. I'm stoked and am now hunting for an appropriate, lightweight bike to use with a 35cc Honda 'inframe'. Makes me wish I hadn't sold my American M16. It was all Shimano DeoreXT, and when I shipped it to the new owner, all boxed and surrounded with packing material, the shipping weight was 26lbs.