1950's Vintage Briggs Motorbike Build.

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silverbear

silverbear

The Boy Who Never Grew Up
Jul 9, 2009
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northeastern Minnesota
I've been staring at your belt tightener setup. I'm in the middle of planning a build ("kindalikeawhizzer") for a 1951 Schwinn cantilever with a 147cc Jacobsen engine with belt drive to a Whizzer sheave at the rear wheel. I have not yet determined for sure how I will do the clutch. If I understand the photos of yours, the pedal is connected to an armature with an idler pulley on it which engages the belt. Is that right? And if so then it means the pedal is no longer able to pedal the bike forward, which in your state is OK, but in my state is not OK. You mention a manual Whizzer clutch. How does that work? I've been thinking I would use an automatic clutch at the engine with chain primary to a jackshaft and from the jackshaft belt final drive to the sheave. Maybe the Whizzer manual clutch is simpler...?
SB
 
C

curtisfox

Well-Known Member
Dec 29, 2008
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minesota
Motorbikermark said:
Haven't ridden it much, I live in the mountains of N.C. so not being able to launch from a stop without pedals is really a deal breaker (too many hills to push off from) if all else fails may have to add pedals or move to flat land. Entered it in a large local car show and got a top 20 out of 150+ cars.
[IMG
With out the need to pedal my leg is well in front of the muffler and well behind the pull start pulley on the other side. If I find I have to add pedals than I may have to extend the exhaust and build a guard for the pulley. I'll keep my progress posted, Thanks for the encouragement.
Click to expand...
Thats AWESOME!
for what its worth my jackshaft was mounted up under the seat behind the seat post ( Wizzer fashon ) with the primery belt on the outside easy to change
 
Motorbikermark

Motorbikermark

New Member
Nov 16, 2011
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Silver Bear a Whizzer manual clutch is like a two step pulley mounted on a swing arm (usually attached to the motor) with equal tension on the engine drive pulley and the rear sheave, the arm is spring loaded usually in the engaged position with a cable attached to the arm that pulls down against the spring to disengaging the clutch. it really is pretty effective and inexpensive. I bought my whole set up for less than $100 off Ebay. I'm more than likely going to fix mount the pulley from the clutch so that I can maintain my clutch design, Just want to be different and try something new.

Curtis I'm probably going to mount my jackshaft (Whizzer Pulley) in line with the drive pulley and the rear axle allowing me to tension the rear belt by moving back the rear wheel and letting me maintain my clutch design on the front belt. But the higher jackshaft would look sweet.
 
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Motorbikermark

Motorbikermark

New Member
Nov 16, 2011
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Western N.C.
Been working on a Jackshaft, Basically its a Whizzer manual clutch thats fix mounted with a tensioner engaged clutch.



Added a filler piece and a small tool box.

 
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curtisfox

Well-Known Member
Dec 29, 2008
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SO!
Just wondering,how is it working out?
Have you had a chance to ride it much? Sure do love this bike .............Curt
 
Motorbikermark

Motorbikermark

New Member
Nov 16, 2011
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Western N.C.
Sorry for the late reply, I've ridden it only shortly. As I suspected the belt I currently have on it are going to slip at low speeds, so I had to roll it off on a hill. I'm going to change them out to standard notched grip belt and may have to go to a taller drive pulley. I just haven't had time to work on it lately which is kind of a pitiful excuse since it will probably take 20 minutes if I take my time. made some subtle changes since the last pics.



 
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curtisfox

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Dec 29, 2008
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So what belt is slipping the large pulley? I had a Monarch twin when i was a kid and don't remember it slipping.
Boy do i love this bike right out of my days as a kid...............Curt
 
MEASURE TWICE

MEASURE TWICE

Well-Known Member
Jul 13, 2010
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I had not looked at this thread for a while. I have a 5S and also a 6S Briggs and like the looks how you set your bike with I'd guess one of those models!

The notched belts I initially thought to use around smaller diameter pulleys I use, but decide to get them for all three on my multi-jackshaft very low ratio off-road bike when I had slipping pulleys.

The smaller diameter pulleys have less surface area and I think are more likely to slip, so I wonder if when you only have slipping on the larger pulley why that might be.

If there is independent adjustment of the tension on the crankshaft pulley and the wheel drive pulley you could try adjusting the drive pulley tighter. That type of clutch from Ebay I know is spring loaded as you mention, if there is not an adjustment per say, a last resort might be changing the springs if possible for greater tension.

I made sure the pulleys where free of grease and grime. I sanded with fine emery cloth followed up by cleaning with acetone and then clean dry cloth.

Other than that I am soon to try swapping out my belts for the notched ones. I tried using some spray on belt dressing and it helped some. I'm not saying to try belt dressing as really it was a last resort till I realized I had not tried using the notched belts.

I won't put the belt dressing on the notched belts until I have tried other things first.

Again, yea that bike has class look!

MT

http://motorbicycling.com/showthread.php?t=29678&page=14 (Post 133 lists the notched belts I'm to try)
 
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