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DIY Home Built Motorized Bicycle (non kit) Post all about your home built rides here. Weedwacker motors, lawn mower engines ect. This area is for non kit builds

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  #1  
Old 09-06-2009, 08:19 PM
olgraybeard olgraybeard is offline
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Join Date: Sep 2009
Location: Eatonville, Wa
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Default 031 stihl mounting

mounting a chainsaw to a bike frame, to have the rotation going the right way, the clutch side of the engine has to be on the bike chain side of the frame is that a problem if I want to retain the petals on the bike for backup or do I have to go to a jack shaft or do away with the recoil start and put a clutch on that side. Also in the 60's-70's they used to use chainsaw engines on go carts are those clutches still available (smaller shaft size). I new so be gentile. oh and after more reading and checking out the bike I'm back to a chain drive. can I move the bike pedal drive (10 speed ) to the left side of bike? Does anyone make jackshaft assy for bike if I end up going that way or give me a idea what bearing/axle to use withth out going overboard or maybe sizing the jackshaft for a gocart clutch and just running a sprocket on the engine. need some feedback whats been done before

Last edited by olgraybeard; 09-06-2009 at 09:34 PM.
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  #2  
Old 09-09-2009, 04:04 PM
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motor_head motor_head is offline
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Join Date: Dec 2008
Location: iowa
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Default Re: 031 stihl mounting

the easiest way to keep the pedals on a homemade chaindrive would prolly be to get the front crank freewheel from the shift kit they make for the china kits
Sick Bike Parts
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then just rig your own jackshaft
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Old 09-09-2009, 07:45 PM
olgraybeard olgraybeard is offline
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Default Re: 031 stihl mounting

To set up a jackshaft on my bike using new parts (one of the 10 tooth will be used on my clutch).This is for a overall gear ratio of 1 to 21 to attain 35 MPH at 9600 RPM (6500rpm max torque rpm for this engine, 12000 max rpm). 10 tooth on the engine and a 48 tooth on the jackshaft drive-in sprocket. That yields a ratio of 4.8. Dividing 4.8 into 21 says the secondary ratio must be 4.375 A 10 teeth on the jackshaft to 44 teeth on the wheel (4.4) will be close enough for the secondary. Math was done by a friend. The price list is below, I would be better buying a kit with engine for $10-$20 and have everything included with new much bigger engine. Being that I'm on disability right now I guess this will be put on the back burner. But I did score a good tank on ebay the other bay. Vintage Moped Garelli Tank,Vintage scooter tank,Garelli:eBay Motors (item 270451305782 end time Sep-07-09 19:32:42 PDT)

jackshaft ¾ “ (2) 10 tooth sprocket w/bearing shaft & support 29.99
Jackshafts & Components, BMI Karts and Supplies - Home
hub for 48 tooth sprocket on jackshaft 23.50
https://www.gokartsupply.com/cgi-bin...f.cgi?viewcart
48 tooth sprocket on jackshaft 18.99
https://www.gokartsupply.com/cgi-bin...f.cgi?viewcart
wheel sprocket 44 teeth 16.95
Wholesale Beach Cruisers, Chopper, Mountain, Road, Tandem and BMX Freestyle Bicycles. - BikeBerry.com
wheel sprocket clamp 9.95
Wholesale Beach Cruisers, Chopper, Mountain, Road, Tandem and BMX Freestyle Bicycles. - BikeBerry.com
TOTAL 99.38

Last edited by olgraybeard; 09-09-2009 at 10:44 PM.
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Old 10-03-2009, 08:11 AM
cornbelt cornbelt is offline
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Default Re: 031 stihl mounting

As far as engine rotation is concerned, a 2-stroke will run either direction. The starter assembly might not accommodate the idea, but the principle is used on golf carts, which use a reverse winding in the starter. If one wants reverse, the windings in the starter just spin the engine the other way. Even a Detroit wiill run backwards.
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Old 10-03-2009, 09:12 AM
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NEAT TIMES NEAT TIMES is offline
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Join Date: May 2008
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Default Re: 031 stihl mounting

Beard, Hi And Welcome. There Should Be Several Atemps For Saw Mounts On Here. Chain Saw Motors Are High Quality, Sthil Being About The Best. Boygofast Has Just Got A New Batch Of China Girl Kits In, 49cc, Steel Sleeve Cylinder, Slant Head With New Style Carb = $117.99. That Is Hard To Beat. "davidsfarm" Has Saw-bike Video`s On - "you Tube Video's" I Spent A Lot Of Time With The Chain Saw Idea, And Gave Up. Here Is A New Idea, Just Popped Into My Head ( And I Have Not Even Had My Morning Coffee). The Main Problem Is The Engine Rotation. Use The "golden Eagle" Belt Drive Parts. The 31cc Saw Motor And It`s Rpm Range Should Be Perfect. They Use Direct Drive, No Gear Reduction. The Very Large (about 18" Dia.) Nylon Cogged Sheave Snaps Onto The Spokes, The Approx 1" Dia. Drive Pulley (cog) Has A 5/16" Nf Female Thread (right Hand Thread). Golden Eagle Is A Very Proven System. The The Belt Is $25., The Top Cog Is $25. And The Large Sheave Is Around $40-$50. Now You Have To Mount It On The Right Side.your Peddal Chain Is Going To Be A Problem, To Clear The Nylon Sheave. Maybe Reversing The Sprockets On The Rear Cassette Would Work. (put Large Sprockets To The Outside For Pedal Power, So Chain Will Miss The Scheave. Dam, The Drive Pulley Will Screw Off The Crank. It Would Have To Be Welded To Saw Clutch Drum. I Think Your Sthil Has The Sprocket On The Outside , Which Helps. I Am Figuring This Out As I Type, Never Thought Of It Before. D Bore Cogs Are Available From Suppliers. You Need To Use The Clutch. They Are Tough. I Need My Coffee Now!! Lol. Well, Something To Think About Anyway. Saw Motors Are Difficult To Mount. Have Owned A Tree Service For Over 30 Yrs = I Always Say: Chainsaws Are Like Women, A Good One Is Fun, A Bad One Will Drive You Nuts!! Imho Ron .
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