Idea phase of my 2-stroke build...

Latitude42

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Mar 2, 2019
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Ok, 1st thank you guys for all the useful info on this forum!!! This place is awesome!

My build idea is I have a Huffy 26" men's bike with 3-speed nexus hub/ coaster brake, beach bars, rear rack & originally had factory saddlebags. I have a 98cc 2-stroke 3hp Tecumseh engine off of a Toro snowblower I want to use in it.
I know I will have to get a different carb that is adjustable as the stock carp is single speed w/no air/mixture adjustments. I will need to make or find an intake because I will be changing the angle of the engine from it's original position on the blower to one that works with the "V" in the bike frame to get the new carb level so the float works correctly.
I have seen the "wizzer" style set-up where the engine goes back to a jackshaft, then to a LARGE rear wheel sheeve via a long V belt. The simplicity of a similar design is appealing. Put a centrifugal V-belt pulley clutch on the motor, skip the chain to pulley jack shaft and go straight back to the large sheeve on the rear wheel. Put a manual belt tensioner in somewhere to engage & disengage the drive. Maybe put a 12 volt generator as the tensioner to charge a battery. All the drive is on one side, simple and easy?
But, I've read that the Wizzer was ok (40mph) on flat roads, but a pig when hitting any incline..? Being my displacement is larger I'm not sure if my proposed set-up would have better performance. I would like to achieve 40 mph ash & be able to do some hills.

Idea #2...same clutch on motor to pulley on traditional jackshaft setup to my front sprocket to allow 3-speeds via rear hub. Install disk brake on front and rear & ditch coaster brake. Seems a more complex setup, but if it works would have it's advantages. Pulley and sprocket size would have to be figured out. I would like to keep belt pulley system on engine side to give a little buffer to the chain side and 3-speed rear hub.

Well, let me know what you think of these ideas please.

Thanks.
 
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indian22

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Dec 31, 2014
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Welcome Latitude. I find appeal in both designs presented and others that could be proposed. Complexity is a relative term & once you've clearly seen solutions the complex seems quite obvious & therefore simple. As to the "Wizzer" style belt drive remember that the successful use of belts goes back to the very first of "drive train" design bicycles motorized or not. I've ridden alongside belt driven bikes on steep terrain and noticed they kept pace with chain drives quite well.. depending on pulley ratio & power output of bikes so equipped. The Wizzer 5 plus hp belt drive bikes with comparable drive ratios actually had the power advantage and pulled better than less powerful, but chain driven bikes. That being said the belt adjustment & it's condition (as well as the pulleys) would naturally need be within wear tolerances.

I personally build chain drives, but admire the well constructed & period correct look of the belt and schieve drive & in talking with those who are currently building and riding this drive type, I've not encountered any complaint as to it's performance even when using engines that develop twice as much power as the Wizzer.

At any rate 3hp engines and drive train combinations that will run an honest 40 mph on the flats will definitely feel the "pig" on moderate to steep hills due to the final drive to reach 40 mph, coupled with lack of power...expect to pedal a bit.

Best of luck whatever design you select & enjoy the process & the ride!

Rick C.
 

curtisfox

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Dec 29, 2008
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minesota
Read through this build, https://motorbicycling.com/threads/excalibur-09.37011/

I had a factory Monark when i was a kid back in the 50's almost the same as Whizzer, Belt drive work great if set up right, and are much more quieter then chain. I am doing a new build with belt drive, but very slow at it as lack of time. Belt tensioner is better because, there is no worry about clutch slipping. .................Curt
 
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indian22

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Curtis that's a great thread link you provided, Mr. B built a long lived belt drive that is an excellent example of the type & a beautiful bike that functions well.

Rick C.
 

curtisfox

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Yes! he was my inspiration to go forth with my build. Sorta don't wait around just do it, and make changes if needed. I go back and read his post every so often, just to get recharged.............Curt
 

Latitude42

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Mar 2, 2019
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Thanks for the input.... yep, I think 40mph is asking a bit much for a 3hp. I guess I was looking more at the 98cc of the engine. I might be able to bump that up a bit, need a different carb anyway & I'll have to make a totally custom exhaust. Maybe I should look for a solid 30mph and be able to do a bit of an incline.
I think I'll skip the clutch though and just have a tensioner... it would make it easier to play with different gearing then.
I ordered a mikuni for it today, I'll set it up on a bench mount to get it things going.
What about lacing the wheels with 12 gauge spokes to keep things a bit stronger, think that would be needed?

Thanks
 

Citi-sporter

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Jun 16, 2014
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Consider a suspended fork with at least cantilever brakes That Nexus coasterbrake gearhub isn't up to being the sole brake for combined bike and rider weight doing over 30mph.