My second build..Thanks to all of you.

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phatcruiser

New Member
Sep 23, 2013
95
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San Diego
Hello,

Just finished my first in-frame build. What a good experience. I learned so much. When I first came to this website and motorized bikes a couple of years ago it was all I could do to install a friction drive. Over the course of the last couple of years I have read many threads on this site and realized that an in-frame build is possible. Thanks to you guys and gals I was able to start and finish the build. A great big thanks to all of you!!

Took it out on its maiden run. No Dice. Determined that the CDI is shot. A new one is on order.

The next issue is the chain line. It is off by .24”. Sprocket adapter cannot move over due to the activation arm on the coaster hub. The chain is tight enough. Have to use a tensioner as the chain will hit the chain stay without it. Rode the bike up and down the street trying to see if I could get it to jump off the sprocket. Couldn't do it—but when the clutch is disengaged the chain bounces up and hits the black metal guard, supplied with the kit. It’s really noisy and annoying.

Should I remove the guard that came with the kit? Noticed that many MB’s do not run the guard.

Is a ¼” acceptable? I’m thinking I’ll have to buy a torch and bend the arm.

What say you?
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Phat, glad you've gotten this far and your problems are minor. The coaster brake arm can be bent cold. No need to purchase a torch. It just requires a 'Z' bend, just enough to clear the sprocket fasteners. If you have access to bench vice that's all that's needed.

1/4" is a little much. If you can reduce that by half you should be good. The closer you can get to perfect alignment is best.

As for the chain hitting the chain guard; my guess is the chain is too loose or the guard is mounted too close to the chain. There should be some adjustment room there. Look at how the guard is mounted at the rear and simply raise it a little. I personally run a chain guard on all my bikes for safety and for looks. Some need to be trimmed in places and mounted well.

Pedaling with the clutch disengaged will allow some slack in the upper chain run and I assume that's where the chain is hitting.

As for the chain tensioner you must remember that it is intended to be a 'tensioner'. Not a guide. Once the chain and sprockets are aligned the tensioner is there only to allow adjustment in chain tension. It should not 'drag' the chain to either side but be centered so that the wheel rides centered on the chain. That often requires a slight bend or twist in the tensioner bracket to get the wheel to align with the chain path.

Tom
 
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phatcruiser

New Member
Sep 23, 2013
95
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0
San Diego
Tom,

Thanks for answering. I appreciate it. I'm not sure the chain would clear the stay even if the chain line was perfect.

I'll bend the arm and do it right.

Thanks.

Mike
 
bluegoatwoods

bluegoatwoods

Active Member
Jul 29, 2012
1,581
6
38
Central Illinois
Hello, phatcruiser. Since you don't post a lot, you're not as familiar to me as some of these guys. But I'm pretty sure I recognize you. I'm glad things are working out.

Anyway......as far as the clearance between chain and chainstay goes you can usually get yourself some space for adjustment by switching out the bearing cone lock nuts. Often times one will be pretty slim while the other is pretty thick. Moving the thick one to the chain side sometimes helps.

I've even sometimes added an axle lock nut onto the axle between the cone lock nut and the chainstay. But a second cone lock nut in the same place would work just as well.
 
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phatcruiser

New Member
Sep 23, 2013
95
0
0
San Diego
The chain line is perfect. It was time consuming as the sprocket adapter had to be square to the hub and perfectly aligned with the front sprocket. I never lost my cool and just kept at it a little at a time and finally got it. It was actually fun and I enjoyed the challenge of it. Time just flies by when working on the bike. Listened to some good tunes and enjoyed being out in the garage with the smell of gasoline and oil.

Found a gas leak where the petcock bung is welded into the tank. Applied JB weld around the bung.

Still waiting on a couple parts from a couple of vendors.

Bluegoatwoods--I added a second axle nut as a lock nut on the side of the hub with the activation arm which helped center the wheel
There isn't much room between the chain and the bracket used to hold the motor to the seat stay. The chain will hit it without a tensioner. I also have vertical dropouts. If they were horizontal I could see forgoing the tensioner.

Right now I’ve got it dialed in. I’m sure I’ll tinker with it as time goes on and I learn more. I’m leaving for Florida on Wednesday night and won’t be back until next Tuesday. By then I should have all of the parts I need and can button this up provided nothing else goes wrong.
 
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