I have one of the 6.5 HF. The output shaft is 3/4". If you remove the gov. rejet carb, put on a pipe header and 18lb valve springs you will get over 10HP from it. This engine is used by many in the cart racing community. A few more mods will produce 13 to 15HP. That's about as far as you may want to go with this engine. This is a clone of the Honda 6.5 which is sometimes modified to put out 40 to 48HP for cart racing. All of this is way too much power for a standard bicycle frame and would put life and limb in danger! But! Some are building a stronge frame and using this kind of power mated to a comet 44 torque converter. It can be used to repower an old motorcycle with a dead engine.
tjs whats a comet 44 torque converter and where can I get one I wanna make something for property in Wisconsin may be rear mount it on a trike not for on the road use kinda like a homemade 4 wheeler need it to haul stuff around thiunk it can work I have a 6hp honda on my power waSHER works great funny I was looking at it wondering if something like it would work let me know Larry
I would try looking on Ebay, search for Comet torque converter. They are not so easy to find now that comet is out of buisness, but can still be found by searching. also try: http://www.bmikarts.com/shop/index.php?keywords=verter
They sell comet torque converters and have the 44 series but you may have to get it as parts instead of a whole unit.
Action alert! HF 79cc Greyhound on sale until 11/25
Harbor Freight has the 79cc Greyhound engine on sale at $94.99 until 11/25/10. If you get any number of magazines Harbor Freight advertizes in they have a 20% coupon you can clip and use on most items. You can use it on this sale. I just went today, used the coupon that I clipped from my Car & Driver magazine and was out the door with one for $75.99 plus tax!
The Q-Matic is slightly less for the 49 CC motor because it is the stock production drive and we mfg. in large quanities. The Q-Matic for the HF motors uses a more expensive AX series belt and a larger primary pulley, therefore is more costly [not much difference].