Chainsaw bike

[Crna Legija]

Don't ignore the need for an overrun clutch. Otherwise, if you close the throttle and coast, you may have lubrication issues.

Don't most bikes have bearings that let you coast with the petals still, I think if you keep the stock rear wheel and gearing in them that wont be a problem.

[ramses]

Don't ignore the need for an overrun clutch. Otherwise, if you close the throttle and coast, you may have lubrication issues.

Don't most bikes have bearings that let you coast with the petals still, I think if you keep the stock rear wheel and gearing in them that wont be a problem.

Yep, wow, I completely forgot about that.

I'm curious how you would leave the pedals operable with the engine. I guess you could switch the chain between the engine socket and the pedal socket.

[dewey-1]

Must run in a 4 year cycle!

http://www.spudfiles.com/forums/help-wi ... 11395.html

Ever wonder why these projects never seem to get finished or even some pictures posted with success?

[jackssmirkingrevenge]

Ever wonder why these projects never seem to get finished or even some pictures posted with success?

Teh sexeh blondes are distracting?

[jrrdw]

Don't ignore the need for an overrun clutch. Otherwise, if you close the throttle and coast, you may have lubrication issues.

Don't most bikes have bearings that let you coast with the petals still, I think if you keep the stock rear wheel and gearing in them that wont be a problem.

Yep, wow, I completely forgot about that.

I'm curious how you would leave the pedals operable with the engine. I guess you could switch the chain between the engine socket and the pedal socket.

The ability to coast comes from a ratchet drive mech. on the rear axle. A/any 2 stroke engine will not burn up idling, they are getting all the lube they need for the immediate engine speed presuming the gas mix it right.

If I my self were building this project I would get rid of the bike crank and mount the engine near the bottom center as possible then run the rest of the hook ups and add foot rest/pegs.

[stuffbuilder]

I'm curious how you would leave the pedals operable with the engine

At first I was just going to run a second chain from the gearbox down to the wheel sprocket and never shift to that gear, but now I'm realizing that would cause the engine to also drive the pedals as if I were pedaling 30mph.

[Technician1002]

Ever wonder why these projects never seem to get finished or even some pictures posted with success?

Teh sexeh blondes are distracting?

I don't think that one will pass as a moped. I don't see any way to pedal that one.. the bike I mean.

[jackssmirkingrevenge]

I don't think that one will pass as a moped. I don't see any way to pedal that one.. the bike I mean.

Pedalling, perhaps not, but I can picture riding both

[stuffbuilder]

New plan: I'm attaching a separate sprocket to the other side of the wheel that will be dedicated to the engine. The problem now is how will I attack a 9-tooth sprocket to a chainsaw clutch? I thought the chainsaw chain hooked onto the outside of the clutch, but I just realized it hooks up between the clutch and the saw body.

[stuffbuilder]

Ok so I finally got a saw to use. Its a 46cc Craftsman.

Hopefully this isn't too much power for a bike; I would have gone with a smaller engine, but this one was actually cheaper than most of the smaller ones

[Crna Legija]

I think the bigger on is better now you can gear it down if need be and get more torque.

[stuffbuilder]

The problem is that I don't know how much to gear it down. I estimated 24:1, which will make it go about 35mph at full throttle, but I'm not sure if that will give it an unneccessary amount of torque.

[ramses]

Hopefully this isn't too much power for a bike

No such thing


As far as gearing goes, you need to think about the max top speed you want, and find how fast (in RPM) your wheel needs to go. Then compare that to the redline RPM of the engine. The ratio is the gear ratio you need.


If you gear it too much, you'll accelerate faster, but will hit the redline before you want to. If you gear it too little, you'll accelerate slower, and never actually reach full power (or have the ability to go faster than what you deem safe) If you preserve the derailleur system, do the calculation in the highest gear (smallest back sprocket)

[stuffbuilder]

I won't be hooking it up to the derailleur, I'll be hooking it up to a separate sprocket on the other side of the wheel.

And how does a centrifugal clutch behave at different rpms? I know that at speeds just higher than engaging speed they tend to slip more than at redline but that's about it.

[MisterSteve124]

Must run in a 4 year cycle!

http://www.spudfiles.com/forums/help-wi ... 11395.html

Ever wonder why these projects never seem to get finished or even some pictures posted with success?

I actually did finish it, and it worked. Problem was I didn't really think about the proper gear ratios until the end and the clutch got burned out. Let me know if you have any questions, but you seem like you're going in the right direction