Thoughts on BikeBerry's FD Kits?

the drop from 49cc to 35cc (in my personal opinion that i just pulled outta nowhere, not based on any experience with the smaller engine) is the drop from motorized bicycle to motor assisted bicycle. that said, my brike is heavy so on a lighter frame you would probably be fine with the smaller motor (depending on rider weight)

I have no experience with friction drive kits but have put a huasheng 49cc inframe on my bike, i have one of the grubee style toothed belt transmissions with the freewheel in it, seems perfectly fine to me, but honestly it is something I would have rather got a better deal on (i live in canada so there are very limited options here) but I am using a clam-shell hub adapter, and though they can be expensive they seriously reduce the headaches of getting the chain drive working (boo rag-joints)

by the looks of things you are in the price range to get an actual honda engine in your kit. I would recommend doing this. the huasheng i have is perfectly fine but I would have got the honda instead if i wasn't looking at double the price for the privilege (again this is a canadian price thing, you shouldn't have to worry about)

you've mentioned you like the look of the rear rack mounts, and so I feel the need to point out that you in fact can utilize a chain drive with that mounting set up (i wanna say that statton sells such a kit but honestly I'm not sure about that) I know I'm kinda pushing the chain drive but I feel that it is a better system than friction (because I like things to be more complicated and have more moving parts, derp)

in conclusion: more displacement is usually a good idea, huashengs are fine but hondas are better, and as far as the transmissions available for a four stroke go the "hoot" style one (fully enclosed metal box, contains double width roller chain inside) is the crappy one, the gruubee style "4G" or "7G" is pretty good (has a toothed belt and a plastic cover, possibly with a cutout) and the Q-matic is considered the best (built in tensioner, higher build quality) I personally am using the gruubee style one and having no issues (though it had a couple of build quality issues when i got it, nothing that got in the way of it working) and unless I was looking at the same price would get another of this style over the Q-matic, I am not convinced the Q-matic is as much better as they tend to cost, though it is obviously a better product.

all of that being said friction drives are wicked simple to use and put together, much less work.

Since you are talking about next summer which is a long ways away, I would suggest doing some serious looking at what others here have done with self made friction drive setups. Cannonball 2 is one builder with a lot of experience in this area. My ride this summer has been with a rack mounted friction drive setup utilizing a found at the dump MTB. My engine is a robust and inexpensive 79cc four stroke Predator from Harbor Freight which can usually be had for around a hundred dollars. The drive wheel utilizes a used 3 speed Sturmey Archer hub so that I have a three speed gear choice. Even with new tires and tubes along with new Kool Stop brake pads my total expense is less than $250.00. This friction drive has been a reliable and fun ride.
http://motorbicycling.com/showthread.php?t=58705
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