Hi there I think but I am not entirely sure but I just wrote an email explaining all of your issues was that you ??? Corwin Here is a copy of the email that is sent out
First of all the Honda and 4G where made for each other they both are the best of the best. Honda has a 5/8 shaft witch requires a different transmission and the 4G trans for the 5/8 shaft just happens to be 3/4 of an inch more narrow and gives it an advantage over the standard 4G it also has a larger clutch than the standard 4G. Now Huasheng 142F-cc has a tapered shaft the only advantage to this design is it has a bearing in the clutch bell instead of a brass bushing like the Honda 4G. But the standard 4G kit is wider and has a smaller clutch. Husheng also has a engine with the 5/8 shaft this I also have a kits in this configuration as well. Same as the Honda but less money and this kit has all the advantages the Honda has at a lower price. Now you can use any size sprocket you like on these kits it all depends on what you want to do 56 tooth good for climbing hills 25 MPH cruising speed or the other way with a 44 tooth and you cruising speed is around 32 MPH there also is a 48 tooth. You might be thinking about the new 4G but is not on the market yet 4:1 ratio 4G with changeable belt pulleys and well it is not out yet and that kit will only be for the Huasheng with the tapered shaft. And 4G will work with any gear configuration including you 21 speed. Here is a link to a video I made for seizing your bicycle for a 4G engine kit YouTube - How to measure your frame for 4G T Belt Drive kit with HS 49cc 4 Stroke Engine
If you have any concerns please give me a call anytime if you get the answering machine please leave your number and I will call you right back I am never to far away for the phone. Make sure you check my website closely I have all of this information on the site http://blowbyumotorizedbicycles.ca/
I hope this was helpful to you.
LOL OK I have every thing you need to do your kit just let me know