Largest displacement friction dive? Or most HP?

[Blackstar]

New guy here. Curious how much power has been ran through a friction drive, or the biggest engine you've seen driven this way? I'm Attempting something a little rediculous. Im getting ready to strap a built Honda GX200 onto the front wheel of a bike. The motor is a brand new GX200 with ported gx160 head, 26lb valve springs, 3 angle valve grind, 1.3 ratio rockers, flat top piston, governor system removed, billet flywheel, timing advanced 8 degrees, carb bored to .625, 140 e-tube, 92 main jet, etc. Havent dynoed the motor yet, but should make about 16hp @ 5k.




Im building the front fork from scratch so I can support this monster and its 3" spindle. The header pictured will be ditched for something more low profile and a bit tamer sounding. This was just for bench tuning. The recoil will also be removed in favor of a screen, and the motor will be bump started.

 

[grinningremlin]

Crazy, but my hat's off to you.What you're concerned with first is: making sure the spindle is of sufficient diameter so as not to spin and burn a hole in the tire on high/quick throttles.With a 52cc I used a 1.25 inch spindle and still it spun on the tire.Second, PLEASE, if you get this working, go out to a BIG parking lot and do some slaloming and evasive maneuvers to see if you can handle it before you engage any caged traffic.I believe this will be the biggest problem, other than the fun of having to change a flat on the road.
Best of luck, and document it here please, GG.

 

[darwin]

That's scary on the front with all the weight and torque.........let us know how it went when you get out of the hospital.

 

[MotorBicycleRacing]

Largest displacement friction dive? Or most HP?

you win..........maybe? if it is even driveable?

 

[seanshonda]

its been almost a yr., did it ride? you alive?
that's a lot of weight on front tire, if I had that motor, id put it on a trike.

 

[butre]

I was doing a belt drive hf212 build a while back but it cost too much money in tires so I had to scrap it. it was sitting at around 10 horsepower and with a 3 speed was good for at least 50. that engine and transmission are on a go kart now and it's still a little little ridiculous even with an extra 8 inches of contact patch

 

[seanshonda]

was it on your front tire? it would be cumbersome w/ 20# on front tire, plowed steering when wet/off road.

 

[butre]

it was center mount, not rack.

 

[HeadSmess]

pffft. some early cars were FD....

so, 3 litres, 1/2 hp...

 

[rawly old]

Off the top of my head, I'd say about the max. practical hp. on a
bicycle frame FD is 3 hp, maybe a stretch at 4, top rpm around 9000.
Much over that, and you'll be putting a tire exec's kids thru college.