212cc friction drive.. Will it work or not?

[Motorbike Mike]

Ok work with me here. I’m thinking about mounting a 212cc cylinder forward with a simple transmission plate to a friction wheel.

The reverse jackshaft wouldn’t be needed but.... if the friction drive didn’t work I could use is to power a sprocket on the left side.

Will it work? Why or why not?

 

[Ralpho]

I like the way you're thinking here. It needs a way to tighten against the rear wheel I think, maybe a lever that locks it in place with a spring to slide it forward and a spring loaded tensioner to pick up the chain slack. I had an idea like this but abandoned it because the more I thought about it, it kept getting more complicated. It was a steel box with two sliding rollers with a chain running to it. This could allow more power without trashing rear wheels in theory but never made it happen. This was on a left side forward rotating engine.

 

[Ralpho]

Is that a chunk of pvc on your mock up?

 

[Motorbike Mike]

I like the way you're thinking here. It needs a way to tighten against the rear wheel I think, maybe a lever that locks it in place with a spring to slide it forward and a spring loaded tensioner to pick up the chain slack. I had an idea like this but abandoned it because the more I thought about it, it kept getting more complicated. It was a steel box with two sliding rollers with a chain running to it. This could allow more power without trashing rear wheels in theory but never made it happen. This was on a left side forward rotating engine.

It would tighten to the rear wheel by a slight pivoting hinge at the front motor mount bolts. Rear motor mount bolts would just be pinned guides. And yes the mock-up mount is pvc.

 

[FNTPuck]

I do not think it will work properly as a friction drive IMO. Too much TQ, you will never be able to get the benefit of the 212 with a friction drive setup since you will have to baby it all the time or else you will constantly be changing the rear tire. Maybe a 79cc setup with a robust way to mount the roller to the wheel with lots of pressure. The 212 will slip every time you give it gas with any blip of the throttle and shred tires - a 212 is a lot of power for even a chain drive setup.

If you can get the tension on the jackshaft high enough to not let the center reverse sprocket skip links, you can run a chain setup off that and then it will work...just make sure you have good quality 12ga wheels and decent hubs at minimum.

 

[Motorbike Mike]

I do not think it will work properly as a friction drive IMO. Too much TQ, you will never be able to get the benefit of the 212 with a friction drive setup since you will have to baby it all the time or else you will constantly be changing the rear tire. Maybe a 79cc setup with a robust way to mount the roller to the wheel with lots of pressure. The 212 will slip every time you give it gas with any blip of the throttle and shred tires - a 212 is a lot of power for even a chain drive setup.

If you can get the tension on the jackshaft high enough to not let the center reverse sprocket skip links, you can run a chain setup off that and then it will work...just make sure you have good quality 12ga wheels and decent hubs at minimum.

Yes exactly what you said but... my jack shaft (adjustable forward and backward rear axle) will be attached directly to the engine and I won’t be using a small metal low traction roller.

I’m betting the farm on drilling out .125- .1875” diameter .25” deep traction holes drilled into a large/wide contact rubber roller so it would get enough traction to ride wheelies.

 

[Motorbike Mike]

I haven’t seen a hybrid chain/friction drive combo out there yet but... engine mounted chain/friction drive systems will certainly be the next most popular drive method once someone can figure out the drive traction engineering. Less throttle + higher speed.

I just got a new Predator 212 and Ironically it cost less than the eBay hardware parts to build this friction drive system. I’m hoping to put it together in the next few months. I’ll post it back here if I get it done and working.

If it doesn’t work on a bike maybe I’ll just put some blades in place of the roller and make a walk behind ditch trencher with it lol.

 

[Deleted member 26224]

Yes exactly what you said but... my jack shaft (adjustable forward and backward rear axle) will be attached directly to the engine and I won’t be using a small metal low traction roller.

I’m betting the farm on drilling out .125- .1875” diameter .25” deep traction holes drilled into a large/wide contact rubber roller so it would get enough traction to ride wheelies. View attachment 91677

Not gonna work. You know those bearings swivel right? The forces pulling then pushing are going to wear those things out quick. You’ll need another bearing on the other side of the wheel driver.

Also that little diameter is not going to drive a tire. Friction drives work best with low torque engines.

 

[mark20]

I haven’t seen a hybrid chain/friction drive combo out there yet but... engine mounted chain/friction drive systems will certainly be the next most popular drive method once someone can figure out the drive traction engineering. Less throttle + higher speed.

I just got a new Predator 212 and Ironically it cost less than the eBay hardware parts to build this friction drive system. I’m hoping to put it together in the next few months. I’ll post it back here if I get it done and working.

If it doesn’t work on a bike maybe I’ll just put some blades in place of the roller and make a walk behind ditch trencher with it lol.

you would have to gear the engine down (ie instead of 10:1 do 1:2 )
to make it viable you would have to do that so the engine doesn't push all the torque down low (the 212cc makes close to 8ftlbs of torque, a average friction drive motor makes less then one) but still has enough that it pushes it up hills with minimal slippage

but you need as-least 1/4 hardware to make that work (add to the fact that frame reinforcement is a MUST)

i would personally make it with that jack shaft, then get a lawnmower style belt, figure out some way to tighten and loosen the belt (with a lever similer to a clutch) then reduce the gearing to the final friction drive (with the lawnmower pulleys). so that way the you can slip the belt to start and you can lock it out when your up to say 15-20, then you can have the full range without needing to compensate torque


this build seems interesting, good luck!

 

[Motorbike Mike]

Not gonna work. You know those bearings swivel right? The forces pulling then pushing are going to wear those things out quick. You’ll need another bearing on the other side of the wheel driver.

Also that little diameter is not going to drive a tire. Friction drives work best with low torque engines.