Go-kart Engine Swap

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  #1  
Old 01-28-06, 08:30 PM
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Go-kart Engine Swap

The Yerf Dog kart I have now has a 6hp engine. I'm wanting more power and there's a cheap complete '73 Artic Cat snowmobile 440cc for sale near me. If I put this engine on the Yerf, how hard is this going to be? I was told that if I get bigger shocks (which I have), the frame and swing arm should be able to handle the bigger engine. Does any know if this is true? I was also going to use the transmission and maybe the brakes (aren't they connect to the trans?) and anything else that could be used.
 
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Old 01-29-06, 12:36 AM
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Engine Swap

Hi, I would not recommend an engine swap with the Artic Cat snowmobile engine. That engine is not ment to be operated in warm weather and it's over 30 years old.
I would go with a 13hp Honda engine or an Honda equivalent like a Vortec that you can find on ebay for around $200.00. These air cooled four stroke engines are fine for warm weather.
With the 13hp engine swap you probably won't have to change springs.
You may also look into changing gears {sprockets} for more speed.
Best regards, Jeff
 
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Old 01-29-06, 07:27 AM
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Snowmobile engines can be used in warm weather, it is only a myth that they cannot. I was thinking of gettting a 13hp engine before, but I'd need a new torque converter so the price is the same as the snowmobile.
 
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Old 01-29-06, 06:20 PM
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Engine Swap

Hi, You can operate almost any engine in cold or hot temperatures but it may not be doing the engine any good and it will not be at it's peak performance if it is operated way out of the temperature range it was designed for.

When engineers design a engine they have to determine what the best operating temperature will be for best combustion and performance. They also have to design the cooling for the engine to maintain this operating temperature range in the air temperature range the engine will most likley be operated in. The fuel mixture with cold air verses hot humid air also is a big factor.

Some motorcycle engines have to be driven almost an hour at 60mph in 70 degree air before the engine oil reaches it's proper operating temperature to lubricate and flow to factory specs. If this engine was being operated at 30 degrees outside air temp which it wasn't really designed for the oil flow and lubrication will not be as good.

I used to race snowmobiles with JLO engines in the winter and summer and we had had some serious heat problems in the summer. The biggest problem was the engine getting to hot and the pistons swelled. This caused really bad cylinder wall scuffing.

If you decide to use the snowmobile engine see if someone makes new pistons for it using new technology. There might even be someone making Hypereutectic pistons fot that engine. These pistons expand very little under high heat. As far as oil goes I would use a synthetic oil for your mix.

If we had better pistons and synthetic oil 30 years ago, alot of our summer engine problems may have been solved.

Good luck and best regards, Jeff
 

Last edited by Jeff Z; 01-30-06 at 07:21 AM.
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Old 01-29-06, 07:36 PM
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I'm still going to go with the snowmobile engine. How much would the new pistons cost? How warm will it have to be before I start running into problems? Thanks for the help.
 
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Old 01-29-06, 09:38 PM
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Engine mod

Hi, It's been alot of years since my racing days but I think it was well over 400F internal cylinder wall temperature when bad things started to happen. At these temperatures the top center of the piston is probably pushing 600 F. The pistons and the oil back then couldn't take the heat. New synthetic oils can.

As far as prices on pistons I do not know what they cost know. Best check with your dealer or search your engine on ebay or Google. You can also check with Wiseco Pistons online.
www.pistons-online.com


With that engine that kart will be a fast one.
I'm building a 13hp mini bike with a front ski for the ice and a front tire for summer. Had to build a new swing arm for the wide rear tire and I had to enlarge the frame so the engine would fit. I'm starting to think 13hp engines were not ment for mini bikes. At least not for normal people. This bike will be quite a monster.

Best regards and have alot of fun with all that hp, ~~~Jeff~~~
 

Last edited by Jeff Z; 01-30-06 at 07:48 AM.
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Old 01-30-06, 11:56 AM
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set up the carb to run a little on the rich side and try to duct some air to the cylinder area. see if anybody's running these engines on methanol.
 
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Old 02-13-06, 08:10 AM
diagnosticmonke
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Talking Now Thats A Good Idea

Im originally from MN and Ive stuffed 2 cylinder sled engines in everything from old golf carts th cushman scooters. A mig welder made this all possible alond with percise measuring and a power hacksaw. My dad owns a snowmobile salvage yard and a vast array of muscle sleds. There is a guy in Illinois that runs Twins on his honda oddessy at there track and he is pretty much the man to beat. Oh, I havent heard JLO in a long time Jeff, Thats a bad word where I come from, makes a guy say things he doesnt know was in his vocabulary when tryin to start one, not to mention the recoil design.Amen
 
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Old 02-15-06, 11:47 AM
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Right now I'm building a frame for a first project. Here's a link to some pictures.
http://photobucket.com/albums/v681/M...a1981/Go-kart/
 
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Old 02-17-06, 05:12 AM
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Go Kart

Hi, Saw the pictures, post more in the future.

A note to Diagnosticmonke: You have got that right. JLO was not the best choice in engines back then. Sachs was the way to go. I had to modify the JLO's to beat a stock Sachs.
~~~Jeff Z.~~~
 
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Old 02-17-06, 02:50 PM
diagnosticmonke
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Ahhh, the Memories

Yea, How bout them Wankel Rotorys, What a scientific discovery that was !!!
 
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Old 02-21-06, 12:13 PM
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Got the frame and swing arm welded. http://photobucket.com/albums/v681/M.../?sc=1&multi=4
 
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Old 02-23-06, 08:52 PM
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Front and the a-arms are almost complete.
 
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