CVT Tranny on a Happy Time Motorized Bicycle

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ferball

ferball

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I just realized the thread title may be misconstrued...

I know that CVT transmissions are nothing new, and the discussion is usually about 4 strokes or pocket bike motors, but I have been thinking that a CVT transmision might work with our beloved Two strokes.

As I research the idea I can find no technical data on any CVT transmission, and I seeing that I do not have the budget to buy one at the moment, I was wondering what type of RPMS they operate at, and what not, I have managed to find that most CVT go from a 3:1 Ratio to a 1:1 Ratio. Which could be used to give considerable boost in benefit if integrated right into the bike. Does any have the technical data on a CVT tranny?
 
Russell

Russell

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Apr 19, 2009
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Re: CVT Tranny on a Happy Time

I have a CVt and pocket engine sitting around. They are pretty wide, to build in frame. Seems that to connect a CVT to a HT is not easy as thier is a built in RPM reduction. When I get time I will build the pocket/CVT into a in frame bike. The major problem is the pedals.
 
ferball

ferball

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Re: CVT Tranny on a Happy Time

My thought was to drive a CVT with a chain from the HT and mount the CVT on the seat tube/chainstay above the sprocket..
 
Russell

Russell

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Re: CVT Tranny on a Happy Time

The problem that I see with that is the rpm of the CVT. It was designed to run at aprox 6K max RPm. With the gear reduction built into the Ht 4:1 you will never come near that. And with the output of the HT being 10 tooth you can not gear it up.

Russ

ferball said:
My thought was to drive a CVT with a chain from the HT and mount the CVT on the seat tube/chainstay above the sprocket..
Click to expand...
 
corgi1

corgi1

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Re: CVT Tranny on a Happy Time

Why not ,,,10 tooth from HT motor too a jack shaft 10tooth and from the jackshaft a 40 tooth too a 10 tooth on the CVT,,now the CVT imput gear is at HT motor rpm
 
Russell

Russell

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Re: CVT Tranny on a Happy Time

Yes that sounds like it would work, especially if we had Hp to spare. With the losses in the jackshaft X the built in hp loss of the CVT we might be be better off with the standard drive.(just my opinion not nessarlly fact). However it would take up space.

Russ
 
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corgi1

corgi1

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Re: CVT Tranny on a Happy Time

I would think the CVT fell in the catagory of a shift kit ,voiding the Hp issue so much for the start-out gearing too the high gear running,,I know the CVT looses some Hp but susposedly so do chain drive shift kits ,It is made up for in the gearing advantage,,,,and on the post above,to finish the drive,, as the CVT imput was increased to the motor rpm the output of the cvt needs to reduce back through something for the useable power too the wheel,poss. a reduction trans (1-4)on the cvt output endThey may already be designed into it
 
Russell

Russell

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Re: CVT Tranny on a Happy Time

Corgi,
You win, I don't have a clue what you are trying to convey.

Russ
 
corgi1

corgi1

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Re: CVT Tranny on a Happy Time

I'm just doing the gear ratios directions (aprox.) to run the cvt with a HT motor for the 6000 rpm and that having the cvt transmission gearing would compensate for the hp loss ,,,(previously it was stated that 6000 rpm was needed to operate the cvt,and ht motors are aprox. 6000 rpm but geared down through the clutch so the motor's 10 tooth sproket rpm output needs too be increased for the cvt to operate,thus the J-shafts)
 
Andyinchville1

Andyinchville1

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Dec 26, 2007
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Re: CVT Tranny on a Happy Time

HI,

Interesting idea....I've been thinking about that too....only other possible issue would be how to start the engine...Pull start? or somehow incorporate pedal start mech and chain ring freewheel like the shift kits to start the engine before the CVT?

Andrew
 
corgi1

corgi1

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Re: CVT Tranny on a Happy Time

run a crank gear chain too a free wheel on the first J-shaft ,or pull start
 
ruppster

ruppster

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Re: CVT Tranny on a Happy Time

I'm not familiar with pocket bike cvt's, I do have a bit of experience on snowmobile cvt's though. Typically on a cvt the primary clutch(motor clutch) controls the engine speed of the motor by shifting out at an rpm controlled by the fly weights. You tune the clutch to the power curve of the motor by the mass and curvature of the clutch fly weight. The secondary clutch has a helix and spring that controls shift out and back shifting. I don't want to discourage you but unless you can get tuning components it will be very hard to get the full benefits of a cvt. Trust me when I say that tuning a clutch can give you the fits even when you have the tuning parts on hand. If you want to learn about cvt's you can get a great book from these guys. Olav aaenn engineered the cvt as we know it today. Aaen Performance - High Performance products for Snowmobiles and Polaris ATV's I hope this helps you.
 
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