How to convert chain saw engines for go-carts

[Danny Newman]

I have a 1965 antique go-kart. It has two engine mounts, but each wheel turns independant of each other. Therefore, if I mount two engines, they will have to match, and I have not found one that turns clockwise (in my area). The left mount engine will turn counterclockwise and the right engine will have to turn clockwise. Can I find a matching engine and make it run in reverse. If so, can anyone tell me how it can be done. You used to be able to buy kart engines line this ready to mount.

 

[boltonranger]

That is fairly ambitious.
You could simply flip one of the engines tip to tail to accomplish this.
Or a larger cc motor and power only one wheel. Is that not an option for you?

 

[Danny Newman]

That is fairly ambitious.
You could simply flip one of the engines tip to tail to accomplish this.
Or a larger cc motor and power only one wheel. Is that not an option for you?

I wanted to mount two engines just for the fun of it. Also, you would get equal power to both wheels and help reduce spinning. I am presently trying to find an old McCulloch 450 chain saw. I already have one and wouldlike to mount two of them. I am also considering mounting two different brands of engines and tweek them so they will closly match max rpm and pulling power. The Mc 450 I have has the shaft on the right side where the blade is mounted. I also have a Power Products wih the shaft on the left side.

 

[boltonranger]

Hmmm.
There are some issues to address using 2 different engines. Or perhaps even two of the same type....
Owing to differences in the engines power curves due to age etc, one engine will outpace the other. I’m not sure how you could actually match their output.
A very crude way is matching throttle position, but it may not be enough.

You still might be better off harnessing 2 motors to the same pulley and using a differential.

 

[Danny Newman]

Hmmm.
There are some issues to address using 2 different engines. Or perhaps even two of the same type....
Owing to differences in the engines power curves due to age etc, one engine will outpace the other. I’m not sure how you could actually match their output.
A very crude way is matching throttle position, but it may not be enough.

You still might be better off harnessing 2 motors to the same pulley and using a differential.

This is an antique go kart from the '60's. Had it since I was in high school. Many of the old go karts used two chain saws (both identical, like two Mc 10's, Mc 5's, two Power products, etc. My go kart is designed for two engines with two engine mounts. The engines used at that time were made complete with mounts to bolt to the frame, ready to run. Some karts in the slower classes used smaller chain saw type engines, and the faster classes used two engines on the back, and some even used motorcycle engines, but you had to have a solid axle mounted in bearing blocks welded to the back frame, and some karts,like mine, had each back wheel mounted to only the ends of what they called a "dead axle" which meant the wheels turned independently of each other. I am just trying to re-live my childhood days by fixing my kart up with two engines, which I could not afford when I was young. I was not broke, but badly bent. My main goal now is just fix it up real nice, and hopefully with two engines, mainly for show, and to have some fun with in between. I keep looking for a matched pair of old chain saw engines to convert, but one will have to turn clockwise, and one counter clockwise, because the way the wheels are mounted without a solid axle connecting both wheels. I dont know why they made some kart axles like that, other than some race tracks ran clockwise and some ran counterclockwise. For example, you would get better traction in a sharp right hand turn with the engine mounted on the left wheel, the weight would shift to the left when making a sharp right hand turn, and vise-versa in the opposite direction. ( I put a lot of miles on mine when I was young, and found this out by experience. It might be extremely difficult to find two matching engines with opposite rotations, but I will continue to try. I presently have a McCulloch 450 saw with a 90 cc engine, and it turns clockwise. I am going to work with this one until something hopefully turns up for two engines. Lots of fun. By the way, the guys with two engines on their kart had to match their throttles as close and they could get from idle to wide open. Some had their throttles coupled together on both engines.

 

[wcorey]

The main thing that dictates direction of rotation on most saws is simply the pull start mechanism and they are normally made to go in one direction only, usually counterclockwise looking at it from the left side.
It may be possible on some to flip the rewind spring and starter pawls upside down and wind the rope opposite but I'd think it would require some substantial adaption on most.

On some chainsaw motors I've seen adapted for Karts, the rewind pullstart is removed and a more or less plain pulley is mounted in it's place on the crank, with a notch to hold the end of a knotted rope, oldschool style. Then you can obviously just wind the rope in the direction you want it to rotate.

The other possible consideration is that some ignitions will only trigger in one direction.

Occasionally I hear of a saw running backwards due to a kickback while starting, typically caused by too much ignition advance. Depending on the saw this can cause pretty significant damage to the starter if the pawls don't retract quick enough not to catch...

A good cheap and available source for vintage motors would be ones using the very common power products ah47's, there seems to be an endless number of manufacturers that used those in the 60's. David Bradley, Lombard and Mono just to name a few, many can be picked up at scrapyard prices...

 

[Danny Newman]

The main thing that dictates direction of rotation on most saws is simply the pull start mechanism and they are normally made to go in one direction only, usually counterclockwise looking at it from the left side.
It may be possible on some to flip the rewind spring and starter pawls upside down and wind the rope opposite but I'd think it would require some substantial adaption on most.

On some chainsaw motors I've seen adapted for Karts, the rewind pullstart is removed and a more or less plain pulley is mounted in it's place on the crank, with a notch to hold the end of a knotted rope, oldschool style. Then you can obviously just wind the rope in the direction you want it to rotate.

The other possible consideration is that some ignitions will only trigger in one direction.

Occasionally I hear of a saw running backwards due to a kickback while starting, typically caused by too much ignition advance. Depending on the saw this can cause pretty significant damage to the starter if the pawls don't retract quick enough not to catch...

A good cheap and available source for vintage motors would be ones using the very common power products ah47's, there seems to be an endless number of manufacturers that used those in the 60's. David Bradley, Lombard and Mono just to name a few, many can be picked up at scrapyard prices...

 

[Danny Newman]

Actually, I do have an AH 47 on hand, with the rope starter.

 

[boltonranger]

Ahh..ok I get it now.
Thanks for explaining.
Sounds like a fun “let’s make it work” project.
So, only real issue might be timing on the second engine.

 

[johninky]

Back in the mid 1960s a friend's older brother had a dual-engine go kart that he raced. Thing was able to run 160mph. Had 4WDB and real magnesium wheels. Why he never died young is a real mystery. Still alive and has his own business working on John Deere equipment.

Forgot to mention he also raced a Triumph Bonneville.

 

[Danny Newman]

Back in the mid 1960s a friend's older brother had a dual-engine go kart that he raced. Thing was able to run 160mph. Had 4WDB and real magnesium wheels. Why he never died young is a real mystery. Still alive and has his own business working on John Deere equipment.

Forgot to mention he also raced a Triumph Bonneville.

I recently bought a barn find McCulloch chain saw. Absolutely no I.D. on this saw, but it is one of the "muscle saws" used for cutting timber. There is no pull start on the flywheel side, but it is on the clutch side. Looking on You Tube, it looks like a 700-800 series. It does not have a gear box for the chain, but so many of these saws look alike, I cant say for sure which model it is. But I feel fairly sure it is at least 100CC or more. I have looked at so many videos trying to find some I.D. on this saw, but nothing definite. I have no doubt it will have plenty of power for a go-kart. I am presently tearing it down, got my old kart clutch to fit (the shaft was barely long enough for the clutch to mount), and I am ready to do some dismanteling and cleaning. I had to pull the starter rope assembly off the right side where the chain was, and I have a starter housing from another MC that will fit on the flywheel side. Just have to move the starter ratchets from another saw and mount them on the flywheel. I think I have a winner.

 

[Danny Newman]

I recently bought a barn find McCulloch chain saw. Absolutely no I.D. on this saw, but it is one of the "muscle saws" used for cutting timber. There is no pull start on the flywheel side, but it is on the clutch side. Looking on You Tube, it looks like a 700-800 series. It does not have a gear box for the chain, but so many of these saws look alike, I cant say for sure which model it is. But I feel fairly sure it is at least 100CC or more. I have looked at so many videos trying to find some I.D. on this saw, but nothing definite. I have no doubt it will have plenty of power for a go-kart. I am presently tearing it down, got my old kart clutch to fit (the shaft was barely long enough for the clutch to mount), and I am ready to do some dismanteling and cleaning. I had to pull the starter rope assembly off the right side where the chain was, and I have a starter housing from another MC that will fit on the flywheel side. Just have to move the starter ratchets from another saw and mount them on the flywheel. I think I have a winner.

Oh well. I just got through looking at E-Bay Mc's and I still dont know which model it it. I give up, just so it runs good.

 

[wcorey]

There may be a number stamped underneath on the block that will id the model.
For instance a 797 will be 66251...
There are other tells like decomps and carb types, the guys that frequent the McCulloch thread could likely id it with a pic or two...

 

[James Miller]

My uncle ran a twin engine cart for a season back in the day. Had a pair of mac 125s said it was the most ridiculous thing he ever drove. Dad used to have 5 or 6 of the mac kart motors sitting on a shelf back in the day. Wish I'd have known what they were then. To me they were just go kart motors. Hope you get the kart going again good luck.

 

[dmb2613]

they use to run Macs on them

 

[jwilly]

Some also had a way to eliminate the spark above a certain rpm and they would go diesel when hot. Unlimited RPM.

 

[Ductape]

 

[Danny Newman]

View attachment 727609

 

[Danny Newman]

Now that's what I'm talkin' 'bout. I have a McCullock 450 chain saw that I will be using the engine for my kart. The saw barn find I mentioned seems to have a broken ring. I made a crude measure of the diameter (across the piston) of this saw and compared it to the 450, and both measurements seemed to be the same. Both saws had the larege "pancake" style carb, but each carb has a different number. I dont know what determines the horsepower of these old Mac engines, but my thinking is if the piston is the same diameter and the carbs are very similar (only has different numbers) they should be the same horsepower and CC. I think the 450 engine , according to one source, is 5.5 cubic inches, and about close to 90cc. I am going to google this engine info again. The other engine I bought recently that has the broken ring has a larger (wider) surround at the carb area and a larger fuel tank, but the engine looks exactly like the 450 when completely disassembled. It does not look any bit different from the 450, but the I.D. plate was gone and absolutely no other numbers or I.D on either saw, other that the carb numbers. Does anyone know how to find out what this saw is. I can identify what the saw looks like. It has the starter on the crankshaft side and a black screen like cover over the flywheel side. It is not a geared saw, chain runs straight from the clutch to the blade, and the carb cover is wider than the 450, with the flange inside the carb area that the cover hold down screw threads into, is secured to the sides, not the top of the carb. The flange on the 450 fits over a machined -in bolt that is actually a part of the carb on top of the carb. The carb on the other saw does not have a bolt machined into the carb. Everything else is identical looking. If both engines are the same, then no use to replace the broken ring on the engine I just bought.

 

[rayjay257]

If you can't mount them like in the last pic it's not that difficult to make one run the other direction. It's all about the ign timing. Figure out what the spark is set to on the stock motor and then make the spark happen at that point with the motor turning the other direction. You would basically be retarding the timing a whole lot. If these motors have points then you might have to leave out the woodruff key on the flywheel so you can reposition the flywheel. If the sparkplug hole is straight inline with the piston then you can use a dial indicator to figure out how far down the piston is when the points break and then set up the other motor so the points break at this point but turning the other direction. The piston won't know which way it's going, it's just the spark you have to figure out. I've always wanted to use a GM HEI module on a small motor. Just need a reluctor , a pulser coil [ old Mopar ] and a 12v batt to power it all.