Would you buy a 14’ Pro?

[Big10inch]

I talked to another service manager today and he said how he’s never heard of a leak down test on a 2 stroke snowmobile. He has heard of doing them on 4 strokes. Does the leak down test go by a different name? Maybe I’m describing it incorrectly

Time to find a new place to service the sled. If he has never heard of doing leak down on a 2 stroke he should go be a greeter at wal mart because his current job has outpaced his knowledge.

There is nothing hard or technical about doing leak down tests. It is just a more accurate measurement of how much is getting past the rings because the engine is static while testing. Compression test requires turning the engine over to get results. That is where it starts going wrong with regards to results. There are too many variables that can mess it up.

On four strokes they do leak down mostly to confirm valve seal because that is a more common failure point than rings. 2 strokes do not have valves and the procedure is for ring seal. Different in that way but the procedure is the same and in both cases the results are much more useful than compression tests.

 

[Motorbreath_]

Time to find a new place to service the sled. If he has never heard of doing leak down on a 2 stroke he should go be a greeter at wal mart because his current job has outpaced his knowledge.

There is nothing hard or technical about doing leak down tests. It is just a more accurate measurement of how much is getting past the rings because the engine is static while testing. Compression test requires turning the engine over to get results. That is where it starts going wrong with regards to results. There are too many variables that can mess it up.

On four strokes they do leak down mostly to confirm valve seal because that is a more common failure point than rings. 2 strokes do not have valves and the procedure is for ring seal. Different in that way but the procedure is the same and in both cases the results are much more useful than compression tests.

What happens on a leak down test if you only have damage on the bottom of the cylinder? I know some guys say only damage above the exhaust ports matter.. but if the majority of the damage on the cylinder is in one spot, won't a leak down miss this?
Don't shoot the messenger, I'm still learning about this stuff.

 

[Big10inch]

What happens on a leak down test if you only have damage on the bottom of the cylinder? I know some guys say only damage above the exhaust ports matter.. but if the majority of the damage on the cylinder is in one spot, won't a leak down miss this?
Don't shoot the messenger, I'm still learning about this stuff.

If the cylinder is damaged it is from the rings scraping across it and the rings are softer than the cylinder wall. The rings are designed to be the fail point. If there is cylinder damage, there is ring wear and the leak down will pick it up when you put pressure to it.

From a performance standpoint maybe you could argue that the upper cylinder is where the real action is. Once the piston has moved below the exhaust port pressure in the cylinder drops and the bulk of the power has been transferred to the crank already. However, any damage to the cylinder bore will be reflected in ring seal, as mentioned above. Damage below the ports is no better because there will still be ring damage and it will show up in the leak down results, maybe just a little further down the road.

The key to leak down is monitoring. Increasing numbers will tell you when a rebuild is coming due. Stable numbers are an indication of good health. When they start going up, performance will start going down.

 

[bowhunter11199]

Time to find a new place to service the sled. If he has never heard of doing leak down on a 2 stroke he should go be a greeter at wal mart because his current job has outpaced his knowledge.

There is nothing hard or technical about doing leak down tests. It is just a more accurate measurement of how much is getting past the rings because the engine is static while testing. Compression test requires turning the engine over to get results. That is where it starts going wrong with regards to results. There are too many variables that can mess it up.

On four strokes they do leak down mostly to confirm valve seal because that is a more common failure point than rings. 2 strokes do not have valves and the procedure is for ring seal. Different in that way but the procedure is the same and in both cases the results are much more useful than compression tests.

Thanks for the info Big10 and all the above posters! I will continue to call around and hopefully I can get someone knowledgeable on the phone and talk to them about getting the sled to them.

The owner of the pro and I originally agreed upon $4k but I told him I’m still keeping my options open and looking at other sleds. He came back with a price reduction at $3850. To be continued...

 

[Flying Dutchman]

Putting the leak down discussion aside, from what you've told us, the sled sounds like a good machine and price is good. I'm assuming you can't test ride? IMO the track is fine, couple misc dents in the rolled edge of tunnel is nothing. The oil catch can is weird, since that's more of a car/truck thing, but easily removed. Wrapped pipe is also strange, not sure why and shouldn't there be a tin clam shell?

FWIW, I've had great luck with my Poo's.
My first Pro was a snow checked 2013. Now sold to a buddy and is still running strong. The track had some fraying in the first year, which I singed off, and is no worse for wear now. Oiler turned up from day 1, and never had a problem (oops, one A-arm separated which we glued back together a couple years back). Even the original drive belt is still going, inspection shows no need to change.

I purchased a new 2015, which came with a 3 year warranty. Again turned up the oiler a bit. Only thing I ever done under warranty was a solenoid for the exh valves. Engine runs great. Whatever compression means, my gauge reads 118 at 3000' and it's been like that from new.
I just changed the original clutch belt before the last mountain trip in March, only cause I figured it was time but it still looked fine.. The 15 has a chain case, so I've lowered the gears a couple notches, but that's about it.
Always run premium fuel, engine warm up, and go. Besides the regular checkups, cleaning, new set of plugs every year, these machines have been trouble free.

FWIW, we have 3 more Pro RMK 800’s in the group, 2014 + 15 and none have had engine problems.
If I was personally looking for another PRO, I would have no problem buying a 2014.
Just my 2 bits.......good luck with your shopping

 

[mountaincat 800]

It's a crap shoot buying a used sled no mater the brand. Your getting a ton of great advise on here. My experience when buying used is I would look for a Pro that has been left completely stock, not left outside and preferably trailered in an enclosed. Also compare the hours on the machine.

 

[black z]

If I was buying a used pro, I would ask the owner what he thinks about the cooling system, that should tell you if he let the coolant temp stabilize after shutdown before hammering on it again. I have ~2300 miles on my 14 with ~1000 under 7 lbs of boost out west and 3-5 lbs at sealevel. Still runs like new. I add oil to the fuel, run good fuel (non oxy-91 and 110), turned up the oil pump, and balanced the clutches.

 

[bowhunter11199]

Update... Called around some more today and I’ve come to the conclusion there is not a snowmobile dealer/mechanic shop in the state that will perform a leak down test on a snowmobile. Most act like they have no idea what a leak down test is, the rest say they only do it on 4 strokes

 

[summ8rmk]

Wow, it is so easy to do.
Take a sparkplug out of each cylinder, find tdc, screw in leakdown tester, use a tool to firmly hold the primary clutch, slowly turn up air pressure till u reach desired point.
Record readings, turn down air till 0. Rotate primary 180°, same process for the other cylinder.

Polaris [emoji2955]

 

[05rmksteve]

And that's why I dont trust a dealer to work on my sleds.

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[BeartoothBaron]

Update... Called around some more today and I’ve come to the conclusion there is not a snowmobile dealer/mechanic shop in the state that will perform a leak down test on a snowmobile. Most act like they have no idea what a leak down test is, the rest say they only do it on 4 strokes

That's sad, but not a total surprise. Fact is, most shops just want to get paid to swap parts, and too many are outside their comfort zone if they don't have a "replace part A for error code X" solution. I do pretty much all my own work, in part because finding someone who cares about the quality of their work as much as I do is difficult these days. There are still some shops out there with high standards though, so support them when you can.

Anyway, my gut says just go for it with this sled. You're always taking a chance on a used sled, and sleds that check out perfectly still blow up 50 miles later sometimes, but low miles and good compression mean you're not taking that big a risk. A leakdown check will cut down that risk even more, but we're talking smaller percentages. If you're still worried about it and you've got a portable compressor, I'd suggest just buying your own tester. Even if you had to buy the compressor (which would come in handy anyway), you could have everything you'd need for $150 – probably the same as a shop would charge to test it...

 

[05rmksteve]

If you have a compressor I will loan you my leak down tester.

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[bowhunter11199]

If you have a compressor I will loan you my leak down tester.

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Thank you for the offer. I’m thinking about taking you up on that offer because I do have a compressor. It would be the first time ever doing a leak down so maybe I could test the leak down on a lawnmower before I test it out on some guys Polaris Pro RMK 800

 

[05rmksteve]

Would be best to learn how to do the test on a 2 stroke since that's what you will be doing the main test on.

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