Chainsaw VS Kit Engine

Matt Barrack

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May 30, 2017
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99
So I got an old chainsaw that works very good. I also have a motoried bike with an engine from one of the kits you can buy. Would the chainsaw engine work better than the one from the kit? I know I made a thread like this earlier but this is more specific to my build.

The current engine is a 2-stroke 66cc (I believe) engine from a motorized bike kit. Runs rather good and I can get it up to 40 rather quick. Goes faster but hits 40 without trouble.

The chainsaw is a 60's STIHL 08 chainsaw. I don't know what size the engine is but it is pretty big. Sometimes it is a bit of a pain to start but it runs rather good. I would mount it inside the frame, the same basic way the current engine is mounted. Planning on welding some sort of sprocket to the clutch and make it chain driven.

So would this chainsaw work better than the Chinese engine kit? Thanks in advance. :)
 
Last edited:


butre

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Dec 2, 2013
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stihl 08 is a 56cc motor, makes more power than a stock 66cc but doesn't have as much headroom for power. good port job and expansion chamber might net you 5 horses.

a stihl 066 would be more fun, it's 92cc and makes about 6 or 7 horses as it sits on the saw, has enough headroom to hit 12 horses comfortably with the right parts, and 98.5cc big bore kits are available.

either way it'll be a pain to mate them to a bike. you gotta get creative with compound gearing more often than not. they're also a pain to port since the head and cylinder are one casting.
 

Matt Barrack

Member
Joined
May 30, 2017
Messages
99
stihl 08 is a 56cc motor, makes more power than a stock 66cc but doesn't have as much headroom for power. good port job and expansion chamber might net you 5 horses.

a stihl 066 would be more fun, it's 92cc and makes about 6 or 7 horses as it sits on the saw, has enough headroom to hit 12 horses comfortably with the right parts, and 98.5cc big bore kits are available.

either way it'll be a pain to mate them to a bike. you gotta get creative with compound gearing more often than not. they're also a pain to port since the head and cylinder are one casting.
Good to know. Thanks for the heads up.
 

KCvale

In memory of KCvale 1959-2019
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Apr 18, 2010
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3,516
If you want something you can ride in a week, go with a good kit, if you just want a difficult project that will take months and may or may not work, go with the chainsaw engine is my opinion.
 

Steve Best

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Sep 22, 2012
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1,267
k. why wouldn't it work?
As Butre said "if your skills permit".
I got a bucket of skills, I'd need all of them, a good welder and some machine shop tools.
Listen to KC, his advice is solid.

Most of us dream of making something awesome out of parts we have at hand. Often the motivation is saving money. It usually ends up at a dead end when something needs to be paid for. I have done a lot of swaps over the years. V8s into Toyotas, 4x4 van, sled motor into a XL250, and an MX motor into a Blaster. It takes motivation, a clear plan, money and technical skills to make it happen. Got these? You can do most anything...

On the technical side, a chain saw is designed to cut at a constant speed in a narrow rpm band. This is not suited to single speed bike, so plan on making it a shifter. On the positive side, they have an interesting torque curve that will really help keep speed on a hill.


KTM 250 powered Blaster and one really cool old guy taking a nap in the sun (pre-eclipse).
 
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