OCC Schwinn 4hp issues NEED HELP

[Schwinndemon]

Ok here is what i did and the problem i ended up with...

this is the bike i started with for $10....

then i painted it black and cut and extended the front forks 8" and put a smaller wheel in the front....

then i took the 4hp engine off a old snowblower that i had and tucked it in the frame and bolted it down....

then since the direction of the crank pulley was the opposite of where the sproket was on the bike i had to build a jackshaft to bring the power to the other side. AND the reason the clutch is not on the engine is because i didnt have access to one with a 1" shaft size like this engine has. so i have a 3" pulley on the crankshaft of the engine, a 2" pulley (not pictured) on the crank shaft side of the jackshaft, the centrifugal clutch on the drive side of the bike and a chain to the original back tire sprocket which is a 20T. and since the sproket on the clutch was a different size chain i welded a 20T sprocket to the one on the clutch. (all i had)....

now for the ISSUE... im sure you veterans of the motorized bike world here will see issues all over this thing (my first attempt at homemade motor bicycle) the problem is that the clutch engages now but the bike doesnt want to move with me on it at all. if i lift the rear up the tire will go super fast when given throttle. the clutch just smokes if i keep the throttle on too long when im sitting on it. im thinking it has to do with the tiny rear tire sprocket, can anyone tell me what they think is wrong... id rather have a good power to speed ratio. please help!!!

 

[furament]

get a heaver cluch but fer what i know it looks good!

 

[Schwinndemon]

well right now its all show and no go, lol... what kind of stronger clutch do you suggest? this one is rated for up to 8hp go carts.

 

[Bikeguy Joe]

Gear it down some. If the wheel spins super fast and won't move you, it's geared too high.
"A" for effort though!

 

[Bikeguy Joe]

Right now you are geared for 100mph, which it won't do, even pointed down a big hill.

 

[Schwinndemon]

here is what i have now, it is better but still doesnt want to do much, what is wrong here?

 

[Bikeguy Joe]

Use a bigger pulley where the silver one is, or a smaller pulley on the engine.
That will get you closer.

 

[Bikeguy Joe]

Or, alternately, a bigger (more teeth) on the wheel, or smaller one on the clutch.

You are almost there, don't give up. Looks like a killer bike waiting to happen.

 

[Schwinndemon]

im going to try a smaller on the clutch, where the 3" silver pulley is i had a 5" and it didnt get the rpm to engage the clutch. i think its all in the 21 tooth sprocket i have on the clutch, its only designed for a 12 tooth. probably double my power by shrinking it down if i can find that small of a bicycle sprocket that has enough meat to weld. unless they sell replacements for the clutch that are for bikes? idk

 

[Schwinndemon]

its kinda sad that at 145 pounds i can drive my kids powerwheels around the yard but my bike doesnt want to move, lol

 

[Bikeguy Joe]

Yeah, I'd go to a 10 or 12 tooth on the clutch, max.

 

[Bikeguy Joe]

Or, go up many several on the wheel sprocket.

 

[Ibedayank]

That clutch is made to be mounted on the motor it needs to spin a certian amount of rpms to fully lock up and not smoke the clutch pads. By reducing the amount of rpms the clutch spins at you raise the rpms the motor has to spin to get the clutch to fully lock up and not burn the pads inside the clutch. Most centriffical clutches engage at 2100-3100 rpms. using a 10 tooth clutch with a 72 sprocket on your jack shaft on the motor side
other side of jackshaft use a 12 tooth to a 16 tooth freewheel on the hub will give you a gear ratio of 10-1 and 30mph @ 5000 rpm

There is also a way to hook up a chain so it can go to your pedals so you can still pedal the bike.

 

[Schwinndemon]

yeah that was the problem with the whole setup was the engine has a 1" shaft so i couldnt put my clutch on it, i should get a different motor like one of the newer OHV singles that most people use and put the clutch on that.

 

[Ibedayank]

1 inch bore clutches
http://www.mfgsupply.com/gomini/gom...iclutchcentcomet/gominiclutchcometscs400.html

http://www.mfgsupply.com/gomini/gom...iclutchcentcomet/gominiclutchcometscs400.html

cheaper then buying a new motor for sure...
CVT also comes in a 1 inch bore

http://www.mfgsupply.com/gomini/gom...lutchtorqtav30/gominiclutchtorqtav30kits.html

 

[5-7HEAVEN]

The cheapest fix:

Keep the 3" crank pulley. Replace 2" jackshaft pulley with a 6" pulley.

6"/3" = 2:1 ratio.

Replace 20t jackshaft pulley with a 10t pulley. Keep your 36t or whatever rear sprocket.

36t/10t = 3.6:1 ratio.

2:1 x 3.6:1 = 7.2:1 gear ratio.

Your bike should move well.

Unsure at what rpm that the jackshaft clutch will engage.

The simplest fix:

Replace 3" crank pulley with Maxi Torq clutch w/10t sprocket.

Replace 2" pulley and clutch with 20t sprocket.

20t/10t = 2:1.

Install 10t on right-side jackshaft; keep 36t rear sprocket.

36t/10t = 3.6:1

2:1 x 3.6:1 = 7.2:1

No jackshaft clutch to worry about.

Bike will move quickly.