Snowdog/track sled

Cwpwelwiz

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Good morning,

I am getting ready to build my first ever snowdog/track sled. I am using a early 80's Yamaha snowmobile and a predator 6.5 hp engine. Has anyone built one before? Looking for ideas and to-do's and not to-do's. Any information would greatly be appreciated.

Thank you in advance
 

vpd66

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I have not built one yet but have been researching and gathering parts for a couple years. I have 1988 and a 1990 Polaris indy snowmobiles with bad engines. I have a 6.5 Harbor Freight Greyhound engine. I was going to use the snowmobile chassis but decided against it. I've seen a few Youtube videos where people have done it that way. I just don't like the way the chassis is designed and the way the track contacts the ground (if that makes sense?). Plus the snowmobile suspension is just not needed. It adds extra weight and won't work in the summer time. I want to use mine all year around. It seems these are very popular over in Russia. They are called motodogs. There is a Russian forum that has all sorts of info on making these and info on commercial ones. Motodog.au is the website. You have to translate the website and a lot of the info can be confusing because it doesn't translate very well.
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These are a set of very good plans on how to build one from someone in the Ukraine. They are $25 on Ebay and well worth it. I'm going to build mine similar to the plans except to modify a few things to fit the track I have.
 

Cwpwelwiz

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Thank you for the reply and the information, I did buy the ebay booklet for the motodog plans. I guess there is only one thing to do is........start with the project and see where it go's.

Thank you again
 

vpd66

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The plans have some very good ideas. I like the way they tension the track and everything is built very simple. It is also good to see an actual video of the competed machine.
 

Cwpwelwiz

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Well, here we go! Started to disassemble the sled. It looks like I can use all of the controls on the handle bars and the original jackshaft and chain drive. Will finish disassembling weekend then give it a through cleaning. More pictures to come.
 

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vpd66

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Are you going to use a TAV (torque converter drive) or just a centrifugal clutch to drive it? I think you can get away with just a centrifugal clutch has these track sled things are not very hi speed (15=20 mph) machines.
 

Karts of Kaos

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looks like a nice sled. what if you used the snowmobile engine on the snowdog? that would probably be scary fast!
 

Cwpwelwiz

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Are you going to use a TAV (torque converter drive) or just a centrifugal clutch to drive it? I think you can get away with just a centrifugal clutch has these track sled things are not very hi speed (15=20 mph) machines.
I purchased an centrifugal clutch for it. I think I'm going to try this first. If I have problems with it I just may go to the tav set up. Now I'm not to familiar with this set up...... any suggestions on what sprockets i should use? Do I need to add another jackshaft or can I go with the 10 tooth sprocket on the clutch to the original shaft on the sled. I see others that they have the clutch to a shaft/sprocket. From that shaft/sprocket to the original shaft on the sled.
 

vpd66

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Good question on the gearing. Most of the ones I've seen use between 6-1 and 8-1 gearing. The plans I got off eBay has 5.9-1 gearing. I will start with 6-1 ratio. I don't think it would be good to just go right to the drive shaft from the engine. With your 10 tooth clutch sprocket you would need a 60 tooth sprocket for the drive shaft to get 6-1 ratio. That would be a relatively big sprocket on the drive shaft and you might run into clearance problems. I too think a centrifugal clutch will work just fine in this application. The plans I have show it with a centrifugal clutch and with a TAV. It say in the plans that you will only get more top speed with a TAV.
 

Mr_mcrib212

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why not just try and get the 2 stroke going, there are very easy to work on, you might have to replace the spark plugs and possibly the carb but other than that it should be good. Is it stuck?
 

vpd66

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why not just try and get the 2 stroke going, there are very easy to work on, you might have to replace the spark plugs and possibly the carb but other than that it should be good. Is it stuck?
Obviously by your location you have never worked on a snowmobile before! LOL Old snowmobiles are a love/hate situation. You love them when they run but hate them when they don't and have to work on them. The problem is they only get used for a couple months out of the year. The rest of the time they just sit. So if you don't properly take care of them then they become very problematic. I've owned snowmobiles for more then 40 years (yes I'm old). Your constantly chasing fuel system problems because of there short season. The second most common engine problem is crankshaft seals going bad. A leaky crank seal will make a very temperamental machine. To properly repair them most of the time you have to split the crankcase or totally disassemble the engine. I hope you can detect my sarcasm. I can totally understand why he is disassembling what looks to be a perfectly good machine!
 

Cwpwelwiz

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I had this machine for a few years and yes I had it running. It never ran good enough to have on the ice. So, I decided that it would be better for me to disassemble it and lighten it up and make a track sled out of her. I'm not looking for a fast ride, just want something I can haul my gear. For me its more practical and economical.
 

Karts of Kaos

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Obviously by your location you have never worked on a snowmobile before! LOL Old snowmobiles are a love/hate situation. You love them when they run but hate them when they don't and have to work on them. The problem is they only get used for a couple months out of the year. The rest of the time they just sit. So if you don't properly take care of them then they become very problematic. I've owned snowmobiles for more then 40 years (yes I'm old). Your constantly chasing fuel system problems because of there short season. The second most common engine problem is crankshaft seals going bad. A leaky crank seal will make a very temperamental machine. To properly repair them most of the time you have to split the crankcase or totally disassemble the engine. I hope you can detect my sarcasm. I can totally understand why he is disassembling what looks to be a perfectly good machine!
right there with you, I am working on a '72 a/c panther with a bad crank seal. it will sure be a pain to fix. I should have fixed it during the summer but I did not know about it then.
 

Snaker

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Yeah, times have changed on those engines.
The last engine I rebuilt was a bit ago now, a 488 Fuji Polaris. A iron lined air cooled twin, about the simplest twin out there.
My plans were to do it up nice. It had been a bit of a hiatus for engine building and I got quite the sticker shock.

I planed on one-overing both cyls with Polaris piston, exchange crank, Polaris crank seals and aftermarket gasket kit. No mods, just stock.
I did a price check and it was $750, with me doing all labor except boring.

One cyl was still in tolerance so I skipped that.
I had the dealer replace just the mag end crank bearing, although after watching the mechanic, I should of done it myself and saved $90.

So after cutting back it still cost me $450, on a engine going into a $200 machine.

I've had a pretty good selection of classic sleds and I don't even attempt to go through the engines, just clean up and fix up the outsides.
 

Karts of Kaos

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my sled was 75$ and the only parts I got so far are the plugs for the tank and hifax. the sled also came with a spare engine so I am pretty sure it was worth the price.
 

vpd66

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These old snowmobiles are a dime a dozen here in Wisconsin. You can literally get them for nothing. If you see one laying in a yard just stop and ask. Most times you can get it for free or very cheaply. Like Snaker said the cost of the parts alone most always goes over what the sled it worth in running condition without factoring in labor. Also these old sleds aren't easy to work on. I started working on these when I was 12 years old. Later when I got my drivers license I took interest in cars and found them much easier to work on.
 
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