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Tool Talk Discussion Forum

Snowmobile

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paulver

10-06-2007 16:56:37




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Okay boys and girls, .... I've never operated one of these, nor have I ever operated "on" one of these, but anyway:
The day we bought our farm, my father-inlaw bought a 1971 Ski-Doo 640 TNT snowmobile at the auction for $2.00, just to be funny. After moving it around the farm for three years trying to find a place where it isn't in the way or providing a home for the groundhogs, I finally took a good look at it. It's in fairly good shape, but the engine is stuck. It's a 1971 Rotax 640 with dual carbs. I've talked to a few parts dealers, and they say it's well worth saving. My question is.... what's the best, quickest, and easiest way to "unstick" the engine? I've already taken the heads off and poured some "PB Blaster" onto the pistons. If that works, how do I actually turn the shaft see if the pistons will move? It's a rope pull start, and I'm afraid to pull it too hard for fear of breaking it, causing one more thing to repair. I've ordered a service manual for it, but it hasn't arrived yet. I'd like to have it up and running before the weather turns cold. Any, and all info/help would be greatly appreciated.

Thanks. Paul

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paulver

10-08-2007 19:29:23




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Thanks for all of the suggestions guys. I managed to free it up today after a few days of soaking, and a little "persuasion" from my hammer and a block of wood. Only one of the pistons was stuck, and I was truly surprised at how easily it moved. I was prepared to use any of your ideas if the one I tried first didn't work. I'll be sure to check out all of the "innards" before reassembling it.

Thanks again.

Paul

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Rod in Smiths Falls, ON

10-08-2007 18:03:17




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Are you sure it's seized and not just really hard to flip over?

I have one of those 640's on my Alpine, and it's all I can do to pull the starter cord.

Anybody want a good '77 Alpine, complete with all manuals?



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Bret4207

10-09-2007 05:09:37




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 Re: Snowmobile in reply to Rod in Smiths Falls, ON, 10-08-2007 18:03:17  
That the double tracked job Rod?



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flying belgian

10-07-2007 18:40:10




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Well one method that usually works on old tractor engines is to knock the porcilin out of an old spark plug. then drill and tap for greese zerk. fill grease gun with diesel or PB or something like it and pump till you bend the handle.



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JerryU

10-07-2007 16:26:39




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
We worked on a number of these some years ago. They are old sleds and nowhere near as reliable as the new ones. They are fun, though.

A source for parts, at least when we were into old sleds was Central Snowmobile. They had quite a scrapyard.

Link


JU



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havvey

10-07-2007 16:01:59




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Ebay is a good source of parts for rotax engine and old ski doo. Generally the engine is the hardest in them to restore. the rest of the seld is pretty simple. All but the very rare and very early 1960-62; don't bring anywhere near the cost of restoration. I have old ski doo's but nothing in that year.



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kurt:ky

10-07-2007 10:49:03




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Paulver the reason I asked was because if you from the Mich.or In. area I was going to be in them states and it sounded like a good project to help you with.PA is a little far for sorry.



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buickanddeere

10-07-2007 06:48:57




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
If the pistons are rusted tight. The needle roller bearings in the bottom end require replacement now. Or later when a rod goes through the block.



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kwright

10-07-2007 04:51:59




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
As Blue3992 suggested, you really should head over to Vintage Sleds (www.vintagesleds.com) and check around.

These folks are passionate about vintage snowmobiles of all colors and can be a big help.



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Leland

10-06-2007 23:01:24




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
What if you spray liquid CO2 and freeze them a couple of times the contracting then expanding when they warm up should loosen then up some .



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Blue3992 (N Illinois)

10-06-2007 19:44:28




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
www.vintagesleds.com and www.vsca.com are some good sties for vintage snowmobiles.



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davpal

10-06-2007 18:51:52




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Those were a pretty good old sled. We had a new 1971 440 TNT. Actually still have it. There has been a huge interest in the last few years in vintage snowmobiles. 2 stroke engines are more precise and fragile than tractor engines so I wouldn't be beating on the pistons with a block of wood. You are going to have to take off the jugs carefully and probably have them bored and oversized pistons installed. Best thing is to take it to somebody that can rebuild it if you don't have the experience to do it. Track will have to be checked for cracks and suspension should be taken out and serviced. If you get that fixed up and running you will have more people interested in it than if you drive up on a new one. I have both and people really dig the vintage stuff. The only thing a new snowmobile does is go Down in value. The vintage one will hold its value very well. Good luck with it.

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Heavens to Mergatroid

10-06-2007 18:42:08




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
That's funny.

"I've talked to a few parts dealers, and they say it's well worth saving."

That's exactly what they would say.

That is what keeps them in business.

By the time you get it running and need this, that, and a few of those to get it on the trail, then you'll need a few of these and some of that, ect, ect.

You are exactly what the parts dealers want.

I'll bet ya by the time you get it running and done with all the nits and knots, you'll have a bunch more in it than you would if you just picked up a good running used machine that aint 35 years old and rides like a radio flyer wagon with a briggs and stratton turning some conveyor belt with bolts for studs.

Really though the thing is an antique.

I guess you gets some looks when you run down to the store in the Pinto with the slick 50 in the oil.

Geez that thing's probably older than a Chevy Vega.

Sorry.

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paulver

10-06-2007 19:24:07




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 Re: Snowmobile in reply to Heavens to Mergatroid, 10-06-2007 18:42:08  
It's called "restoration". Lots of people do it. Silly me!!!! I thought this forum was for sharing information and ideas, not sarcasm. By the way..... when you abbreviate et cetera, it's "etc", not to mention the other grammatical and punctuation errors!!! Sorry, I guess it's my 35 years of teaching "smart mouths" showing!!!



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Jim K

10-06-2007 19:22:09




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 Re: Snowmobile in reply to Heavens to Mergatroid, 10-06-2007 18:42:08  
Hey I had a "71" Chevy Vega wagon. Was excellent for parking.



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big fred

10-06-2007 19:08:56




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 Re: Snowmobile in reply to Heavens to Mergatroid, 10-06-2007 18:42:08  
Dang! Who peed in your corflakes this morning?



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TimV

10-06-2007 17:48:46




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
paulver: that's quite an old hoss you've got there! If the heads are already off, put a block of wood on top of the piston that's up the furthest and tap it with a hammer.



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paulver

10-06-2007 18:20:53




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 Re: Snowmobile in reply to TimV, 10-06-2007 17:48:46  
Tim:
It has domed pistons. Would I risk damaging it (denting it) by tapping it too hard?

Paul



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TimV

10-06-2007 19:29:56




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 Re: Snowmobile in reply to paulver, 10-06-2007 18:20:53  
paulver: the operative word is "tap". This will do a couple of things--it will create vibrations which will help loosen the rust, and it will move the piston a bit (measured in thousandths or tenths of thousandths of an inch) which will help the Blaster creep into the space around the piston. Tap, wait, tap, wait (at least a few minutes, overnight if you've got the patience) and it will come free. If not, then the problem is down further and you're going to have to dig deeper--as a rule, engines stuck that hard will require honing at a minumum, which will probably require disassembly anyway. The pistons are built to contain an explosion every time the sled fires--you won't hurt anything if you don't go overboard with the hammer. I've done this several dozen times and haven't hurt a piston yet--I have an old Evinrude 6-hp outboard that will freeze up every winter regardless of what kind of snake oil you pour down it. Put a dowel down the plug hole, tap it a few times with a hammer, and run it for the summer!

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kurt:ky

10-06-2007 17:23:01




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 Re: Snowmobile in reply to paulver, 10-06-2007 16:56:37  
Where you locaded ?



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paulver

10-06-2007 18:14:12




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 Re: Snowmobile in reply to kurt:ky, 10-06-2007 17:23:01  
Western, PA. North of Pittsburgh.



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