Chainsaw in frame build

[leaded50]

When building a Cruiser/boardtracker styled bike, i did it at an vintage (-54) cycle. Because then i could also use it with an motor, claimed by national laws here in Norway.

But to find the old cycle engines arn´t easy here, and the few are pricy, or owners dont wanna sell. Then ist only the lawnmower /chainsaw/weed whacker motors.

For me, and my purpose, a chainsaw engine is small enough..(approx 50cc) got one for free...

Moods: Because my original crank arn´t wide style, just original 110mm, the width is crucial, to not interfere with the pedals. The hole crank &pedals ar made in one unit, lightly to get ruined when trying to widen it.

 

[leaded50]

My choice of motor is a Jonsred Turbo Chainsaw (even if i didnt found a turbo....it was just some "pipe" from the fan leading air to get cleaner airfilter...)

53cc, and 3,6 hp at 12500...

Cutted away the tanks (oil/gas) of the crankcase, who is made as one unit.
Cutted straight down making a lip in front & rear to bolt up the motor. Kept the part of front housing for fastning of the magnetic coil.
Also the fanblades on crankwheel did go,together with the pull start. This because interference with pedal width. This could be better when mounting the engine even more higher, and more slanted....but wanted the slant to follow the front tube....and had no space to go higher because the tank...

 

[leaded50]

Motorblock finished cutting.....BUT, did one fault....cutted the coilpart away, and had a **** of trouble to fasten this again...(found another crankcase...)

If not cutted away, you keep the ignition right on, just to adjust the space against the crankwheel, if needed!

Finished cutting (with coilpart away too...

 

[leaded50]

Motor mount is made of a rigid thick stainless steel plate, in different angle to let the motor follow the leaning of front tube. (seen on first pic in this thread)
Holes drilled to bolt motor to the edges at front and rear which was kept when cutting the crankcase. Also the forur original bolts to hold the top of the crankcase are longer and goes trough the mount.

Gear ratio: Troublesome........chainsaw motor dont have any reduction gear as a normal motor at use for mopeds, etc.., It will spin at full throttle approx. 12500 rpm! If direct connected, speeds of over 100mph could be shown...IF THE MOTOR COULD GIVE ENOUGH POWER!
Reduction is needed! Made up a jackshaft (axle & bearings w/holders) to get some....

here you also could se the coil housing part is on the crankcase, and the crankwheel have lost the fanblades for more clearence.

 

[NormO]

"Turbo" doesn't really mean it's turbo charged. Yes it is just a pipe to inject air into the air filter to keep it cleaner. It is supposed to help raise the HP some as well, and does by .1HP. Non turbo saws are normally 3HP. Still a nifty idea though to use the flywheel to help keep the air filter cleaner. I wouldn't have removed the shrouds though. You may run into overheating problems down the road. I'm curious about how you'll start it without the pullstart assembly though. Looks like you are off to a good start, keep posting progress please.

P.S. It must be an older saw than mine. I have a CS2152 Turbo that i'm using. 52cc 3.3HP @ 13,500.

 

[leaded50]

Right side. Engine mount is clamped against the front tube & seatpost tube, as low as wanted to clear the chainguard.
Original saw carb are used, just removed filter to change to another later...and made up a stainless steel exhaust pipe, following the angle of front tube.

centrifugal original clutch is still used. This can later be changed to a Go-kart/- type (72mm) if needed, just to cut away the lip around the clutchbell at housing.

I choosd to use a belt drive from the motor to the jackshaft, then it would be easy to change to adjustable tensioner for clutch, and direct sprocket on motorshaft if the clutch wont hold up.
A 7,5" pulley wheel from a washing machine is mounted on the right side jackshaft, and a 1.5" pulley is to be mounted on the clutchbell.

 

[happyvalley]

I love DIY projects like this, the real heart and soul of motorized bicycles. Look forward toward your progress and best of luck with it!

 

[leaded50]

"Turbo" doesn't really mean it's turbo charged. Yes it is just a pipe to inject air into the air filter to keep it cleaner. It is supposed to help raise the HP some as well, and does by .1HP. Non turbo saws are normally 3HP. Still a nifty idea though to use the flywheel to help keep the air filter cleaner. I wouldn't have removed the shrouds though. You may run into overheating problems down the road. I'm curious about how you'll start it without the pullstart assembly though. Looks like you are off to a good start, keep posting progress please.

P.S. It must be an older saw than mine. I have a CS2152 Turbo that i'm using. 52cc 3.3HP @ 13,500.

Found out the case about the "Turbo"..but had some fun with the seller when he sold a new saw to my saws earlyer owner.. he,he.
Fan shrouds....A chainsaw is kept quite still without air coming into it, just from passing slow wind. A Motorbike is aircooled by the airstream at speed, and the chainsaw motor should get the same treatment? Airspeed cooling it!
I belive it would go...and if not, i get another engine! I dont wanna have a fanshroud hiding a bike engine.

Starting......... Got some ideas, and need to test them first... The standard pullstart interfere with the pedals so it had to go.....

 

[leaded50]

I love DIY projects like this, the real heart and soul of motorized bicycles. Look forward toward your progress and best of luck with it!

Thanks!! I hope i dont need to trust only at luck....but that some skills could help too!

One idea of mine is also to not just buy finished, but having the fun of using whats can be used, if needed modify, and all without big costs. Not everyone have the cash to do it, an i be happy to show perhaps one way to get a target, at low cost. I know exactly which one of the engine i wanted, but dont see the fun in just buying, then i could bought a finished set or get someone to fix it all.

Check out this rare German 4 stroke 154ccm motor from the 20´s:
Snob 4Takt Hilfsmotor Gebaut in Düsseldorf anfang 20er J. | eBay

 

[NormO]

I don't know if air movement down the road would be enough or not. I'm too much of a chicken to try it out. I'm also not going very fast most of the time either, but i can understand that you like the looks of a pure engine instead of the stupid looking plastic.

 

[leaded50]

I don't know if air movement down the road would be enough or not. I'm too much of a chicken to try it out. I'm also not going very fast most of the time either, but i can understand that you like the looks of a pure engine instead of the stupid looking plastic.

I´m not shure either, but the fancooling are not so much originally either, and normal airspeed against it should do enough. Motorbikes kept it as aircooled by airstream in many years! At first they used fanshrouds, but when looking, the cooling fins get a little bigger by the years, and they functioned well. so...

 

[curtisfox]

I was thinking about doing this. But never seen it done until now

AWESOME make do with what you have .........Curt

 

[happyvalley]

Yeah, as long as you're not idling in one place for long stretches, I think the air stream moving over the engine will be sufficient to cool it.

 

[silverbear]

Thank you for posting this thread. I have an old beast of a Jonsured (1960's or 1970's) I used with an Alaskan Mill to make lumber. The clutch died on it and clutch parts are no longer available for it, but I had it rebuilt along the way and it still runs strong with a lot of torque. Your build has me thinking it may get a second life on a motorbike with a jackshaft and CVT clutch, maybe from a dead snowmobile.
Anyway, keep those photos coming, please.

NormO, I hope you'll contribute some photos and details of what you're doing. I can see some advantages to a chainsaw engine... lots of them around, compact, powerful, reed valve carburetor, designed to rev high under load all day long. Woohoo!
SB

 

[leaded50]

I belive that too ,happyvalley. A chainsaw motor is quite strong to keep up with their life, mostly at full speed, even its in not so many minutes at time. When talking with a farmer friend, and his father nearby, they done alot of forrest working, and never had a chainsaw ruined by heat or stress, electricla **** on newer electronic ones, and some crumbled by tractor driven over it....but never needed mechanical engine work by wear, only on the normal stuff, clutches,chains, sword, oil clogged by dirt,etc. But, not stopped because melting, or wore out cylinders, even if he still has saws still used in 40years!

 

[leaded50]

I´ll do, silverbear. Even if it could get sometime before new post, take some time to dind parts that can be used here....
And NormO, please post your builds too! Nobody get enough tips & ideas on how to!

 

[NEAT TIMES]

Nice thread, will be watching!

 

[leaded50]

...i wonder why i feel "looked over shoulder"?? he,he!

Thanks NEAT TIMES, ill come back as soon as its new progress!

 

[NormO]

silverbear this is actually my second chainsaw build. I used a Poulan for my first build. My brother has laid claim to that bike however. You can check it out at the Poulan chainsaw build thread. Too lazy to post a link. I will be glad to post info on this build and photos too. Although this build is going to be just a bit different. My avatar is a picture of that bike as well.
Trust me when i say when the engines hit mid to top end they really are awesome. I have found that most saws need the piston rings replaced every couple seasons and carb kit. Other than that the darn things last forever.

 

[Goat Herder]

Hey nice build just saw this one!!