I can tell you how to boost the power of the motor if you're interested:
It works and it was so incredibly easy. First I cleaned out the idle hole in the plastic insert under the idle adjustment screw with a 0.010 wire, then took off the carb and drill out the fuel jet to 0.026 inch, more like reaming, and then drilled holes in the air filter cover for more air, per...
motoredbikes.com
Thank you. Except for checking for any obvious issues, I pretty much threw oil and gas in it and slapped it on the bike. I haven't ran a full tank through it yet, but I do intend to go back though it and mess with the main jet, check rocker clearances, etc at End of Break-In Time.
I've been actually moving towards throwing a 212 on the bike, (I started the project with a Lifan 153F 97cc), and while I was doing that, I saw the 53cc/Belt Drive kit for a measly $170 and couldn't resist. I've always wanted one of the little Huasheng-Type motors for my collection, so it was an "Impulse Candy-Store" buy! I'll keep the 53cc kit for another more practical bike once I've decided to go Full 212 on the Cranbrook.
This is the bike with the Lifan 97cc flathead and TAV2. It topped out at 30mph. So the 53cc kit has bettered that already. I'll try to snap a picture of the 53cc on there, but I'm pretty sure there's a billion "Cranbrook With 4-Stroke Engine Kit" pictures floating around on this forum anyway.
I will keep you posted on how well the kit holds up, in the meantime. As you can see, I butchered the pedals, so the little bugger is hauling my 230lb carcass around without any help from me. I do take it easy until it latches at around 15 mph, and I haven't tried any flat-out speed runs until I change the oil and check the motor first.
