CVT CVT For Smaller 4 Stroke?

Mike St

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Jun 16, 2008
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I see where the X2 CVT has been successfully mated to a 2 stroke engine. I'm a newbie on CVTs, and want to know if anyone has adapted the CVT to a smaller 4 stroke, like a Honda GX 35 or Subaru 25? I want to develop a power system to meet Illinois law if possible. Mike
 

Happy Valley

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Jul 13, 2008
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EHO35a.jpg

Yes to the Honda GX35 and Robin EHO35, both have the 76mm clutch and CVTs are readily available in that configuration.

Not so to my knowledge however with the smaller engines, the Robin EHO25 and Honda GX25 both have the 54mm clutch.
 

Mike St

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I am sure Staton has an adaptor to go from 54mm to 76mm clutches for smaller engines. True? This would mean I could go smaller to GX25. Right?
 

loquin

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You would also need a 54mm clutch drum on the CVT, to mate with the 54mm clutch on the small engine. The adapter just allows the 78mm equipment to physically bolt up to the 54mm mounting.

You may not have enough power with a 25cc motor, as the CVT loses some power (more than a chain drive.) For sure, you can't plan on high speed with it.
 

Mike St

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The law here limits a motorized bicycle to one hp and no more than 20mph, so I'm not looking for high speed. Just moderate speed. A 25 cc engiine sounds perfect.
 

loquin

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Cool. Configure the total gearing (when the CVT is completely engaged at max RPM) for 20 MPH, then the low end falls into place. You're probably looking at a max-torque speed of 5 MPH or so.
 

Mike St

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The question is with this setup, would I have sufficient power to take off from a standstill without pedaling? Any guess?
 

Happy Valley

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My guess would be no but that's pretty much the case with all MBs. The nature of things with a motorized bicycle is a few pedal strokes are necessary to gain momentum to allow the small engines to assist without undue lugging.

There is a member here, though I haven't seen him around much lately, who was happy with an EHO25 but with a GEBE belt drive set-up. He spoke of it being good for his situation: a beach town in southern CA with houses close together so he wanted it quiet, flat terrain near the beach so he had sufficient power.
 
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