49cc Shifter vs 79cc Direct Drive?

Chris Duke

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Hey everybody, I've been enjoying reading posts here while trying to decide on what way to go with my first project. I should be starting to order parts by this weekend, and would like some feedback on kit selection before I start ordering.

It's come down to two choices.
1. 49cc HS kit's set up with a SBP shift kit.
http://www.gasbike.net/collections/...-drive-kit-with-huasheng-49cc-4-stroke-engine

http://www.sickbikeparts.com/catalog/index.php?cPath=21

2. 79cc HF Direct drive setup.
http://www.gasbike.net/collections/...ucts/79cc-monster-80-bike-engine-kit-4-stroke


I figure either would be acceptable. The shift kit would be sweet with the 49cc bike, but I'm guessing that the 79 would be ok by itself with direct drive. And I can't find a direct drive for a 79cc setup, so at least for the moment, it would have to be dd until I came up with my own shift setup.

Does anyone make a primary / trans with the secondary shaft to extend from the left side to the right side of the bike? It would be nice to eliminate the extra jackshaft assy and the additional chains required for that setup.

Or what about a swap over at the pedals? Where instead of on the right side, where it would be coming off the jack shaft, the chain to pedal sprocket just drops down from the output sprocket on the primary / trans instead, eliminating the need for the jack shaft kit. Only problem I see (with my limited experience) would be chain alignment between the two. Or, what about running a V-belt from output to pedal assy on the left side? I don't think it would be too hard to weld a old Chevy or Ford pulley to an extended pedal shaft, but would a pulley fit behind the back side of the primary / transmission plate?

Anyway, some thoughts I had.

So, if you could only have one 4 banger, and your choices were a 49cc HS kit's set up with a SBP shift kit, or a 79cc HF Direct drive setup, which would you get? Advantages, disadvantages?
 
shift kit gives the advantage of gearing up for the highway and gearing down for hills but the disadvantages are the added complexity, 8% power loss, cost.
I'd rather see people spend their money to make the engine more reliable and powerful so the shifter isn't needed.
 
If you are thinking about the 79cc HF, there are many who have done it and you can always add a jackshift/shifter later if you are bored with direct drive. Here is a recent video of a guy working on his 79cc HF, he bought the kit from gasbike and suffice to say you should watch the video and avoid some of the pitfalls he had. In the end, he has a nice bike. I have the 49cc HS direct drive, my transmission just broke some I'm weighing some options. I would go with the 79cc HF if you are decent with tools. I mean in the end you won't regret getting the bigger engine. Also, watch all of this guys videos before buying anything if you got 79cc HF.

 
I would love to have a shift kit. One of these days I will build one. Never seen a 79cc motor, they are usually 66cc. However in most states anything over 48cc is ILLEGAL, and if you ride an illegal bike, you are contributing to the problems all MB riders have to put up with.
 
I would love to have a shift kit. One of these days I will build one. Never seen a 79cc motor, they are usually 66cc. However in most states anything over 48cc is ILLEGAL, and if you ride an illegal bike, you are contributing to the problems all MB riders have to put up with.

he is talking about the Harbor Freight Predator 79cc engine.
 
If you are thinking about the 79cc HF, there are many who have done it and you can always add a jackshift/shifter later if you are bored with direct drive. Here is a recent video of a guy working on his 79cc HF, he bought the kit from gasbike and suffice to say you should watch the video and avoid some of the pitfalls he had. In the end, he has a nice bike. I have the 49cc HS direct drive, my transmission just broke some I'm weighing some options. I would go with the 79cc HF if you are decent with tools. I mean in the end you won't regret getting the bigger engine. Also, watch all of this guys videos before buying anything if you got 79cc HF.




Yep. I watched his video's. Looks a little too big for a MB project. I have a 250cc Yamaha engine. Also too big for MB use.
 
So, are you going with the SBP shifter for the 49cc HS or just direct drive.

For now just direct drive. I found a supplier of beach cruisers cheap. No gears, so no reason for a jackshaft. If I want, when I have the cash, I could add a shifting internal hub with the jackshaft kit. I would still rather have a freespooling pedal crank assy (sprocket on both sides) that I could hook the chain to directly from trans, to transfer from left to right side of bike without a jackshaft. I found some guys who made a prototype, but I don't think they ever went into production. Can't find the video now.
 
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