Intentionally purchased a Super Rat Top End Complete keeping spare parts for my sisters bike. At the time 40mm intakes were not that common and sold out in most places. I found this top end thru Canada with 40mm intake. http://www.motorizedbicycle.ca/cylinder-parts/gt5a-66cc-cylinder-rebuild-kit.html Correct me if I'm wrong please---but it looks as if this would be a 38mm stroke engine. Due to the wrist pin location in the piston. None the less I got some blurry measures well not that bad soes you can't read but they are of the Super Rat Top End. More in my Super Rat Album. Please share any knowledge / experience concerning this motor. Supposedly the electronic ignition is not a sparker box as we are familiar but built into the engine case with the coil.