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Old 01-18-2012, 01:09 PM
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maurtis maurtis is offline
Motorized Bicycle Elite Member
Join Date: Dec 2011
Location: Kyle, TX
Posts: 707
Default Re: Mongoose XR-75 MTB Weed Eater Friction Drive

First off, I want to send a huge thanks to my brother-in-law Dan who put in a ton of time on this project with me, and whose engineering ideas made it a much better build than originally planned. Thanks bro!

So, after the clutch failure, I scoured Austin for a bike shop that actually stocked BMX pegs. The fifth shop I visited had them, and they had a LOT (Empire BMX). I picked up an Odyssey Joystick peg for $15, which fit nicely over the 3/8" shaft and had an outer diameter of a little over 1 1/4". I then picked up some vinyl tubing with a 1 1/4" inner diameter to cover the peg for traction.

I put the peg in the freezer for a couple hours, then put the tubing in hot water, and then used a ton of force to get the tubing onto the peg. It fit great, but unfortunately when heated up by the tire, gradually started coming off of the peg.

Which is ok, since the added diameter took away more torque than I liked. But I am finding that the peg alone, with the weight of the motor and tension springs gets pretty good traction and provides just enough torque to accelerate up the slight hills we have around here and still gives a decent top end.

We also beefed up the bracing on the motor side since the original motor mounts were flexing.

Dan cut the springs to size so we did not have to curl them under the swingarm any more, and we also modified clutch cable to pull from both sides of the scissor lift.

So for now, she is running great. I definitely want to invest in a comfier seat, though, lol.

The next step will be to have a machine shop make me a version of the roller that is a couple inches longer and have a 1.25" flange mount bearing on each side of the roller.

Trying to come up with a name for the bike, I was tossing around "Rygoose Weecycle", but after spending some time in the saddle, it is definitely "The Rattler" LOL.

I also picked up a "double d" carb adjusting tool to adjust the mixture screws since she was running lean, and have a little more giddyup on inclines.

I am definitely impressed with the power this little mill puts out, hopefully the bearing/shaft hold out until I get around to the bearing supports.

Thanks all for your help and experience!

Last edited by maurtis; 01-18-2012 at 01:11 PM.
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