In Frame Chainsaw Motor?

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bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
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living the dream in southern california
a buddy of mine has an old, direct drive racing chainsaw with like a million horsepower (give or take) and i was wondering if anyone's ever built a bike with an in frame engine?

looking at the thing, it looks like i could fab up a gear so it takes a bike chain and run it off that instead of a friction drive.

he said they made go karts outta them, so i was just thinking this might make a cool project, and if anyone's had any experience doing it.

dunno about the gear ratios or anything, it's just in the "could this work?" stage.
 
professor

professor

New Member
Oct 14, 2009
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Buffalo ny area
Of course it would work. But how much work do you want?
Mounting the engine might be a problem. You would have to use the bar mount bolts.
Never heard of a racing chainsaw though. Do you ride them? Hope you don't loose your grip.
 
5

5-7HEAVEN

Well-Known Member
Aug 2, 2008
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professor said:
Of course it would work. But how much work do you want?
Mounting the engine might be a problem. You would have to use the bar mount bolts.
Never heard of a racing chainsaw though. Do you ride them? Hope you don't loose your grip.
Click to expand...
Professor, you're too funny.

The biggest problem is harnessing the high-rpm chainsaw engine. Granted, if the gear ratio is way too high, bike won't run well at all. If gear ratio is a little too high, bike runs pretty good still.

If gearing is optimum, your bike will SCREAM and run like a bat outa helll.

Unfortunately, the common 5:1 pocket bike trans won't bolt on. If you could adapt this to your engine, half the gearing problem would be solved.dance1

Let's see if we can calculate a ratio you can start with:

Fit a 9-tooth #41 sprocket onto the engine and a 20-tooth sprocket onto the jackshaft = 2.22:1

On the other side of the jackshaft, install an 10-tooth 8mm sprocket, link it to a 72-tooth chainring. 72/10 = 7.2:1...

Use a 24-tooth chainring, connect it to a 34-tooth sprocket on an 8-speed cassette = 1.417...

2.22 x 7.2 x 1.417 = 22.67:1...

At 12,000rpm, you're looking at 40.9mph.

This is an EXCELLENT gear ratio for starters. dance1
 
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Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
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You will prolly need a centrifugal force style clutch to catch the motor nice in its power band.
 
Goat Herder

Goat Herder

Gutter Rider
Apr 28, 2008
6,237
20
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N.M.
In high school years and years ago I could curl that[150 pounds]. Still can with more than a couple reps:D
 
LS614

LS614

Active Member
Dec 22, 2009
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CT and MA
There's something called ebay, something else called craigslist :D I got a mcculloch chainsaw on CL, 87cc engine for 25 bucks. See what you can do. They used to make AWESOME cart engines with the mccullochs
 
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