1980 Stretched Schwinn with Briggs 148

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Mar 14, 2013
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San Jose, CA
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Sup people,

Joined this website in 2013 with a project I'd just started and intended to post a build thread.. well after 2.5yrs with a 2yr break I've finally finished my bike. Build thread is here at motorbicycling forum. Since this was my first motorized bike, it took longer than I expected and I put too much time into things that did not work or did not give me the results I wanted. But one thing was for sure, I was on a budget. So that meant getting parts from the cheapest places, usually craigslist or ebay.

The bike is done now. My current and preferred setup is a Max Torque centrifugal belt pulley clutch and a #41 chain final drive. I have tried using different drive trains, those being manual belt clutch, auto belt clutch, Tav2 CVT with many driver and driven tuning attempts. The best is the MT auto. It lacks acceleration below 20mph but once the clutch hooks up fully it really goes.

Valve float at 6200rpm. Top current speed with ratio 8.02 is 47mph, max recorded speed with 7.23 overall was 55mph.
1980 Chicago Schwinn Cruiser stretched 7" lowered 3"
1998 Briggs & Stratton 3.5hp kool-bore, ported, polished, cut eyebrows, head shaved .020", valves lapped and lashed.
Tecumseh H35 adjustable jet carburetor and intake
Water heater pipe curved open exhaust
Max Torque A-section belt clutch, 41 chain, 5/8" jackshaft on pillow block bearings
SBP 8" wide pedal crank
Hayes Stroker hydraulic disc brake with 203mm rotor, rear is handled by engine compression
Front wheel 32spoke 3x, rear 36 spoke 4x left/3x right
26x1.95 road slicks
Bike computer & Tachometer/hour meter
Plated/registered in CA
53mi to a .6gal tank (88mpg)

This is my daily driver and only means of transportation.



With CVT


Bike computer provides Odometer, Speedometer, average and max speed, trip distance and duration, and the time. I reset the trip every time I fill up so I know when I get to the low at 45mi. Tachometer displays engine RPM when running and hours when not.


Steven's Creek Reservoir.


Headlight came stock with H3 halogen and will be getting an H3 LED lamp, something like a 12V 4W.


My first mockup after welding.. when it was already clear what kind of bike this was gonna be.... :)


Next it is getting the dual crown shock from bicycledesigner and a 2nd jackshaft on the other side of the seat tube for a 2-speed transmission and jackshaft disc brake (using a 2nd Max Torque clutch). Going to increase ratio from current single speed of 8.02 to 2nd gear 7.67 which is 100rpm per mph (4000rpm is 40mph, etc)

Have a total of approx 600 miles and 25hrs runtime. So far so good! Get the wave from motorcyclists :D Hope you guys enjoy this long overdue post.
 
what benefits do you get out of having a belt instead of chain off of the clutch? nice bike. I'm running a similar bike and setup. but with a chain. I'm going to move to a moped hub.. sturmy archer 3 speed didn't like the motor haha
 
Yeah.. I saw your bike... You copied me!!!! :p I'm flattered :) the belt actually is there cause I originally set it up for manual belt clutch, then decided to go with auto and just got a pulley clutch. It works well, doesn't mind misalignment and is very quiet and forgiving to shocks... And doesn't sling oil all over your leg. Belts are cheap at the auto store-- 7 bucks a piece. You quickly find that parts designed for bicycles work fine for the CG, but when you get up to the torque of a bigger 4-stroke parts start to break.

An overall ratio of 8.02 is about the tallest ss ratio the briggs will take. With 8.43 the cvt gave me 34mph top.

How fast do you want to go? If you are fine with top speed of 35-40mph, I can sell you my cvt that will give you blistering acceleration.. I drilled a separate set of holes to mount it at a slight upward angle so you can use your jackshaft with it- it will fit just under your exhaust pipe and a few inches from the JS. I have about 150mi on this setup.. But I'm a speed freak. Also different springs you can try for tuning, and a 15t 5/8 sprocket for your final drive. I paid $130 total for it... Find em on ebay for $100 but they need work to fit. Best offer!

For higher speed, cent clutches and chains are the way to go. I'm currently working on a 2-speed auto. top speed in the fifties, 45mph cruise with 2nd gear shift at around 28mph.
 
Yeah.. I saw your bike... You copied me!!!! :p I'm flattered :) the belt actually is there cause I originally set it up for manual belt clutch, then decided to go with auto and just got a pulley clutch. It works well, doesn't mind misalignment and is very quiet and forgiving to shocks... And doesn't sling oil all over your leg. Belts are cheap at the auto store-- 7 bucks a piece. You quickly find that parts designed for bicycles work fine for the CG, but when you get up to the torque of a bigger 4-stroke parts start to break.

An overall ratio of 8.02 is about the tallest ss ratio the briggs will take. With 8.43 the cvt gave me 34mph top.

How fast do you want to go? If you are fine with top speed of 35-40mph, I can sell you my cvt that will give you blistering acceleration.. I drilled a separate set of holes to mount it at a slight upward angle so you can use your jackshaft with it- it will fit just under your exhaust pipe and a few inches from the JS. I have about 150mi on this setup.. But I'm a speed freak. Also different springs you can try for tuning, and a 15t 5/8 sprocket for your final drive. I paid $130 total for it... Find em on ebay for $100 but they need work to fit. Best offer!

For higher speed, cent clutches and chains are the way to go. I'm currently working on a 2-speed auto. top speed in the fifties, 45mph cruise with 2nd gear shift at around 28mph.


lets get something straight. i did not copy you haha. because if i had copied you i would have done it the way you did. i didn't know people had the same idea as me and i chopped the whole back half of my bike off instead of just the bottom and bending it out.. i was working with what i had and what i thought.. if i could do it over agin i would just cut the bottom and do it the way you did… but the way i did it worked just fine.. i also would have liked to use your frame instead of me having to cut my down tube and bend it out and weld in a new bottom piece but its fun.. I'm going to stick with what i have. I'm in the process of redoing my whole jack shelf setup. I'm happy with 40 mph and i can hit that fine with my set up. i don't mined doing a little peddle to start to help the clutch out .
 
Man, this is the stuff of legends. This is why I like what we do; so much chance for creativity to do it's thing. Awesome job dude, keep going!
 

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