I want to share with you how to build an extremely reliable motorized bicycle. If you haven't read my (very bad) experiences with China/Grubee parts, you can do so here:
http://motorbicycling.com/showthread.php?t=37647
Unfortunately, but expectantly, I got burned by the last few parts from China/Grubee I was still using. The chain finally stretched beyond usability and came apart. Of course I was over 10 miles from home. It amazes me how they can engineer their junk to break when you are furthest from your destination. Soon after replacing it, the tensioner pulled into my spokes breaking several of them, and the crappy throttle they sold me broke while installing it on my new friction kit. The admin here didn't give me the last word on the thread I started (cute closing comment Ilikeabikea) but still, those who listened to my advice were rewarded and those who didn't suffered a similar fate as I did I'm sure. I'm sorry, this is not the cheap option. Cost is around $700+shipping. If I were going for the cheaper option I would probably get the Honda kit from flmotorbikes $490 or a Bumble Bee for $250. A strong tire/tube combination as I point out below would also be needed.
Here's the RELIABLE parts list I use:
[$325] One Honda GXH50 or other (not made in China engine)
[$160] One Staton Friction Drive Kit 1 1/8" roller (yes, you heard me right, "friction". I went with Staton because it's made in the USA? NO! Because it's NOT made in China!)
[$130] One centrifugal clutch adapter (I got mine from Staton also in the hopes of eliminating a mismatch with the fiction kit bell)
[$$$] Any ole' bike frame (hopefully not made in China. Funny fact though, I'm using a old Huffy mountain bike that oddly enough has USA stickers on it. Maybe Huffy was once made in USA? hmm... http://en.wikipedia.org/wiki/Huffy)
[$10] One thorn resistant inner tube for the rear (these are heavy and thick in the $10 range)
[$45] One semi-smooth Armadillo tire for the rear (I can't stress how important this is. This is one tough tire that you will need. I read, Continental Grand Prix's are comparable but my local shop carried Armadillo's)
[$30] One optional larger gas tank to get you further down the road before re-fueling
I am so impressed by this bike that I wanted to share it with you. It is hard to believe how long and how far I've gone without breaking down even one time! It's mind boggling. I'm sadden that my $300 EZM Q-matic transmission is now on the shelf, because that is a very nice part. I also still have my brand new untouched Grubee 66cc replacement engine on the shelf that I like to point at with my finger (figuratively) and laugh at as I go in/out of the shed from another long, dependable and very enjoyable ride. "you can't screw me now @#$%^&*@#$! ahahahahahah" or something like that.
Helpful Tips:
* You can rig up a good throttle cable to the Honda GXH50 easily, using the existing linkage and Staton's throttle that comes with their kit
* Do not try saving money on tires/tubes at Wal-(China)-mart or you void this great advice and we absolutely can not be friends!
* Riding in the rain is no problem but you will need to oil the friction roller bearings periodically. (I found that out when the squeaking got pretty loud)
* You will rack up some serious miles so do not forget to change the oil and clean the air filter regularly
* I use a plastic tire liner and and old flat inner tube inside the tire for extra tube protection
* I always carry tools and an extra inner tube just in case. I have not had a flat since using the Armadillo tire/thorn resistant tube
* I have a large knobby mountain bike tire on the front but don't do anything special to prevent flats on it. The rear takes the major abuse, but if you have the cash and get an Armadillo tire and thorn resistant tube for the font, it sure won't hurt
* You can use any tire/rim in a crunch! (before learning the proper tire/tube combination, I had a tire blow out and a flat. Pushed it to my girlfriends and put her old rear tire/rim on my bike and road it home on the friction drive over 8 miles! no messing around with sprockets and chains!)
For those who are the chain-drive-only types, let me say... I was one of you and really expected the chain drive to be superior. But it simply wasn't. I did not think friction was the way to go, but since I've bolted this on from the beginning, it remains untouched from that moment until now. I have been riding it 35+ miles a day to work and everywhere in between reliably without having to work on it, other than for flats until I got that straightened out. I now know this is currently the best and most reliable kit you can buy... so I'm sharing this with you so you won't suffer like I did and you will be able to reliably go from A to B without having to take the bus or waste your time and money on crappy China/Grubee parts.
I hope this helps someone...
John
http://motorbicycling.com/showthread.php?t=37647
Unfortunately, but expectantly, I got burned by the last few parts from China/Grubee I was still using. The chain finally stretched beyond usability and came apart. Of course I was over 10 miles from home. It amazes me how they can engineer their junk to break when you are furthest from your destination. Soon after replacing it, the tensioner pulled into my spokes breaking several of them, and the crappy throttle they sold me broke while installing it on my new friction kit. The admin here didn't give me the last word on the thread I started (cute closing comment Ilikeabikea) but still, those who listened to my advice were rewarded and those who didn't suffered a similar fate as I did I'm sure. I'm sorry, this is not the cheap option. Cost is around $700+shipping. If I were going for the cheaper option I would probably get the Honda kit from flmotorbikes $490 or a Bumble Bee for $250. A strong tire/tube combination as I point out below would also be needed.
Here's the RELIABLE parts list I use:
[$325] One Honda GXH50 or other (not made in China engine)
[$160] One Staton Friction Drive Kit 1 1/8" roller (yes, you heard me right, "friction". I went with Staton because it's made in the USA? NO! Because it's NOT made in China!)
[$130] One centrifugal clutch adapter (I got mine from Staton also in the hopes of eliminating a mismatch with the fiction kit bell)
[$$$] Any ole' bike frame (hopefully not made in China. Funny fact though, I'm using a old Huffy mountain bike that oddly enough has USA stickers on it. Maybe Huffy was once made in USA? hmm... http://en.wikipedia.org/wiki/Huffy)
[$10] One thorn resistant inner tube for the rear (these are heavy and thick in the $10 range)
[$45] One semi-smooth Armadillo tire for the rear (I can't stress how important this is. This is one tough tire that you will need. I read, Continental Grand Prix's are comparable but my local shop carried Armadillo's)
[$30] One optional larger gas tank to get you further down the road before re-fueling
I am so impressed by this bike that I wanted to share it with you. It is hard to believe how long and how far I've gone without breaking down even one time! It's mind boggling. I'm sadden that my $300 EZM Q-matic transmission is now on the shelf, because that is a very nice part. I also still have my brand new untouched Grubee 66cc replacement engine on the shelf that I like to point at with my finger (figuratively) and laugh at as I go in/out of the shed from another long, dependable and very enjoyable ride. "you can't screw me now @#$%^&*@#$! ahahahahahah" or something like that.

Helpful Tips:
* You can rig up a good throttle cable to the Honda GXH50 easily, using the existing linkage and Staton's throttle that comes with their kit
* Do not try saving money on tires/tubes at Wal-(China)-mart or you void this great advice and we absolutely can not be friends!

* Riding in the rain is no problem but you will need to oil the friction roller bearings periodically. (I found that out when the squeaking got pretty loud)
* You will rack up some serious miles so do not forget to change the oil and clean the air filter regularly
* I use a plastic tire liner and and old flat inner tube inside the tire for extra tube protection
* I always carry tools and an extra inner tube just in case. I have not had a flat since using the Armadillo tire/thorn resistant tube
* I have a large knobby mountain bike tire on the front but don't do anything special to prevent flats on it. The rear takes the major abuse, but if you have the cash and get an Armadillo tire and thorn resistant tube for the font, it sure won't hurt

* You can use any tire/rim in a crunch! (before learning the proper tire/tube combination, I had a tire blow out and a flat. Pushed it to my girlfriends and put her old rear tire/rim on my bike and road it home on the friction drive over 8 miles! no messing around with sprockets and chains!)
For those who are the chain-drive-only types, let me say... I was one of you and really expected the chain drive to be superior. But it simply wasn't. I did not think friction was the way to go, but since I've bolted this on from the beginning, it remains untouched from that moment until now. I have been riding it 35+ miles a day to work and everywhere in between reliably without having to work on it, other than for flats until I got that straightened out. I now know this is currently the best and most reliable kit you can buy... so I'm sharing this with you so you won't suffer like I did and you will be able to reliably go from A to B without having to take the bus or waste your time and money on crappy China/Grubee parts.
I hope this helps someone...
John