Weed eater drive shaft extension?

[maurtis]

Hi all,

My first build was going to be 66cc HT motor in a cruiser frame, but as luck would have it, I stumbled across a free Ryobi 30cc weed eater motor on Craigslist a couple days ago. It was missing attachments, but "ran great", so seemed perfect.

Of course, when I got it home I found that it had a brand new spark plug and did not start. I can only assume the previous owner tried to fix it, failed, then decided to dump it on CL. The fix was easy and visible, though, the three screws tightening the cylinder to the crankcase had backed off, so I was losing compression. Tightened them up, and she fired up on the third pull. I just need to take those screws off again and put on some Locktite.

Anyways, on to the issue. I want to build a friction drive setup on my 26" Mongoose mountain bike. BUT, I want to be able to run with a support bearing on each side of the roller. I am assuming this means that I will have to extend the driveshaft. I have not pulled the clutch off yet (I need to pick up a T-handle torx wrench today), but am assuming the drive shaft is a threaded rod. The problem is, I do not weld. Would it be OK to use a threaded coupler to another section of threaded rod, and use JB Weld inside the coupler?

While I prefer the simpler build of not having support bearings, I fear breaking the shaft or killing the motor bearings in a short period of time...

Thanks!

 

[maurtis]

Or am I just blowing the issue out of proportion? This is going to be a "bumping-around-the-neighborhood" bike, so even if I took it to the neighborhood corner store, that is only a little over a mile away. So assuming I put on 200 miles/year, maybe she would hold up for a good while without support bearings?

 

[kev1n]

Hello, I'm sure your engine would hold up without a support bearing. If you want to install one, you could put a bike peg on the original shaft or something similar and locktight it down. Then you could press a bearing into the end of the roller and support it somehow.
GL, Kevin

 

[5-7HEAVEN]

Or am I just blowing the issue out of proportion? This is going to be a "bumping-around-the-neighborhood" bike, so even if I took it to the neighborhood corner store, that is only a little over a mile away. So assuming I put on 200 miles/year, maybe she would hold up for a good while without support bearings?

I broke 2 1.5" friction rollers on my friction drive. Thank goodness the rollers failed instead of the engine. The Mitsubishi engine was installed on a Staton friction drive assembly, but I forgot to install one rear support.

Are you making this with or without a gravity clutch?

 

[maurtis]

For a clutch I am planning on going with a scissor lift, running to a clutch lever on my left handlebar, where a motorcycle clutch lever would be.

Since my current brake levers are half length and the levers I bought for the clutch and throttle are full length, I am hoping to be able to have them both installed on the bars at the same time and still be workable.

 

[cannonball2]

You can set the clutch lever so you can reach under it for the brake. I apply both brakes then just before stopping grab the clutch. I also swap the cables from side to side so I am pulling the front brake on the right like on a M/C. I finally settled on a 1.5" BMX peg for a roller. It worked pretty well.

 

[maurtis]

Hello, I'm sure your engine would hold up without a support bearing. If you want to install one, you could put a bike peg on the original shaft or something similar and locktight it down. Then you could press a bearing into the end of the roller and support it somehow.
GL, Kevin

Thanks for the idea Kevin, I am going to go this route. For my drive roller I am using a long 3/4" socket (I could not find any bike pegs nearby and was too impatient to order one, lol) which has an OD of almost exactly 1". I went to the local bearing supply and picked up a bearing with a 3/4" OD and 1/4" ID. I put a layer of JB Weld inside the socket, so should have a decent press fit once I smooth out the JB Weld.

Thanks!