[i_play_bass]

Seems like all the stickied resources are now dead links, so I apologize for starting a new thread... I had started asking about this in my primary post, but figured it warranted its own post.

I put my first mile (singular) on the 1995 XLT Touring on the weekend, and it wasn't doing so hot when I pulled back into the driveway. Sled had idled fine in the garage and seemed to run fine up on a stand a couple of weeks prior, primary had just been off for work so it hadn't been started in that time. Got everything back together on Sunday but it was tough to start initially - must have taken 15-20 pulls to get it turned over. Once idling it sounded fine. Took off, engaged properly around 4000 rpm, went up the field and back a few times, power was lacking a bit, so I took it back to the house.

Once i got back to the driveway I left it running for a second while I ran into the garage. Came back out and it had shut off. Got it started again after a ton of pulling over, and got it into the garage. I checked the plugs, they were all pretty wet, likely flooded from trying to pull over the engine, but I hooked up the compression tester and Mag & center cylinders were both right around 120, but PTO side wouldn't go above 90. engine was warm and compression was tested at WOT.

Carbs were removed, cleaned, reassembled and synced a couple of months ago before the season started - Air screws set to 1.0 turns per the manual. Idle was set properly to 1900 RPM. All seemed great in the garage before first ride. Carbs were marked to ensure they were put back in the same locations as removed from. Manual indicates same jets and setting for all carbs on the 95 XLT Touring engine.

Now my questions: How to diagnose the problem and then the likely repair?

- I've heard to spray starter fluid near the PTO to check the crank seal since it's that side that's low. If idle increases, I've got at minimum a crank seal that needs replaced, so I'm cracking the bottom end correct? If no change, then it's a different issue - check carb boots for sure. Could exhaust manifold gasket cause an issue also?

- Should I look at building a little leak down tester from a pressure gauge and some pvc/abs? There are a couple of different DIY versions I've seen.

Leak down tester? (2 stroke)

What all is needed to build one for cheap? And how exactly? Also will a bike pump work instead of an air compressor? I know you only put 5-6psi or you risk blowing bottom end seals. How long ahould I wait as well? I saw one guy say wait an hour,...

www.vitalmx.com

DIY Leak down test. - REV Chassis - Performance and Trail Models

Page 1 of 20 - DIY Leak down test. - posted in REV Chassis - Performance and Trail Models: WHAT?? A leak down test is a compression test in reverse. Instead of measuring the ability of the engine to create pressure, we want to check its ability to hold pressure. WHY??? An engine that has an air...

www.dootalk.com

• Is there an advantage to either style? the gauge on the second one is available locally and uses all parts I could find nearby.
• What exactly will a leak down test tell me? I gather it will show where any air escapes from the engine, one cylinder at a time? If I made the second one, that would test all 3 cylinders at once, correct - use soapy water to check for escaping air?
• If an air issue is found, fix before doing anything to repair the piston/cylinder.

- The low cylinder itself - It's still holding some compression. Could be rings, could be the piston itself, could be the cylinder wall? What's the easiest way to diagnose the damage done in the best order? Look inside both the intake and outtake ports for any damage, look inside the spark plug hole? If nothing visible then is it disassemble?

- Just so I'm not setting any unrealistic expectations, I'm assuming best case scenario there's an air leak somewhere, gasket or boot that caused the issue, and then maybe rings in that one cylinder are bad and need replacement? Worst case I've got a crank related issue that will require bottom end work and then maybe a full top end - pistons, cylinder walls and all related gaskets...

Are any of these things beyond my beginner mechanic skills or is there anything I'd have to specifically bring in to a shop to do?

Thanks!

 

[BC_Dan]

usually a center cylinder low compression issue is due to a lean condition due to carburation. Some sleds even require a bigger main jet in the center to keep the air/fuel ratio correct. i would pull the exhaust and look at the piston skirt through the manifold and see if it is scored. You may also be able to see damage on the piston crown by looking through the plug hole.

 

[i_play_bass]

usually a center cylinder low compression issue is due to a lean condition due to carburation. Some sleds even require a bigger main jet in the center to keep the air/fuel ratio correct. i would pull the exhaust and look at the piston skirt through the manifold and see if it is scored. You may also be able to see damage on the piston crown by looking through the plug hole.

It's clutch side though that's now low.

 

[BC_Dan]

ahh, then PTO crank seal is more likely. I misread. Sorry about that!

 

[i_play_bass]

ahh, then PTO crank seal is more likely. I misread. Sorry about that!

That's this guy, correct? This is my actual.

 

[stevem5215]

You are more likely to need to tear down the motor to the crank and have it checked and resealed all over. These just are not good engines. When running good yeah, of course they are nice. But overall I've seen lots of problem children triple Polaris's.

 

[i_play_bass]

So far I'm seeing that first problem location to check is that PTO crank seal. Same with the carb boots on that cylinder. If it's crank seal, I'll be doing a complete tear-down:

- Pull the engine, remove the head and block, remove the flywheel (need a puller or harmonic balancer?), split the crank, inspect crank, bearings, maybe get the dreaded XLT crank oil hole drilled out, replace all gaskets and seals while it's apart, inspect the top end while it's apart. If I've got it apart, should probably do the pistons over.

I gather that the high price of a full engine rebuild is in the labour - because if the crank itself is fine good, it's really only $500-ish in parts for full engine gasket and seal kit and piston kits, probably have a few extra expenses here and there to add to that $500.

Sounds like a lot of money to spend on a 25 year old sled, but considering i'm into it for about $1500CDN including regular maintenance items (bearings, slides, etc) and they're going for $2500-$3000CDN because of huge demand and next to no older supply... It's still worthwhile since the rest of the machine is in good shape.

I know I'm getting ahead of myself, but if I'm going full rebuild, I guess I'll also need the following tools: ring compressor, honer, flywheel puller/harmonic balancer. If crank bearings are poor those need to be pressed on/off correct?

 

[stevem5215]

Yep, more tools. lol never can have enough of those. Right up till you get too old to use them and then a garage sale item for the next person !

I would have the crank index checked. Those things are known to "tweak" and cause lots of problems. A good rebuild on that engine will run you $1500. Forget about snowmobiles as an investment. Think of a money pit where you just throw your money into it. Done simple. No talk of money or it's not worth riding.

 

[i_play_bass]

Yep, more tools. lol never can have enough of those. Right up till you get too old to use them and then a garage sale item for the next person !

I would have the crank index checked. Those things are known to "tweak" and cause lots of problems. A good rebuild on that engine will run you $1500. Forget about snowmobiles as an investment. Think of a money pit where you just throw your money into it. Done simple. No talk of money or it's not worth riding.

Unfortunately if it's going to need a shop to do the work for $1500 bucks, it'd be getting parted out... If I can't diagnose on my own, I'll take it to a shop to get the thing looked at professionally get the verdict, and go from there. $500ish I can live with. full value of the sled on a rebuild and all the good parts on it will be making their way to new owners.

 

[BC_Dan]

You can't use a normal ring compressor to compress the rings, as the con rod is already connected to the crankshaft before you attach the cylinders. The pistons have a pin in them on the intake side to locate the rings, and you can usually squeeze the rings together to get them to slide into the cylinder without a tool. The monoblock triple will be a bit more difficult, I would do the center first then the outside pistons, but maybe Steve or Coolhand have other tricks.

Best two days of owning a snowmobile.. the day you buy it, the day you sell it (kind of like owning a boat!)

 

[Coolhand]

Nope no tricks on a mono-block that is about the best you can do with the piston rings. Always did the center first and then the outer ones as you said. Personally if it was my engine I would do the oil drilling on the crank, find the oil pump upgrade for it as those can be had used usually on eBay or Facebook Marketplace or from some person who parts out snowmobiles, replace the seals, pistons/rings, carburetor boots to be safe and go from there. Yeah it adds to the total but at least you know it will be done right and you can do that stuff yourself if you follow the instructions or videos on it.

 

[TheBearAk]

pull the carbs off and look through the holes at the pistons. Check for scoring, piston skirt issues, etc. None found -- Pull the exhaust off and do the same. Since you can only see one through the manifold (center), it helps to have a borescope or equivalent to look. (I bought one that connects to my phone via WiFi for the display for $20).

Alternately, take the exhaust manifold off and look through.

I have a feeling that you're going to find a busted piston skirt. May have even did more damage, but you won't know that until you have the motor out and on the bench.

 

[Coolhand]

Told him the same thing as well when he told that this had happened. Plus gotta figure out why he lost compression if he didn't break a piston skirt. Hopefully it isn't too bad and can get away with just honing the block.

 

[i_play_bass]

Starting the inspection sometime this week to find the problem. They always say you don't get any snow the year you buy a sled... We got one snowfall of half a foot that partially melted away already.... And now that the sled is on the injured reserve, we've got a foot or more forecast for the next week...

The snow gods tend to be unkind!

Also. Brother in law has a borescope I can borrow. He said he'd help me with the teardown. He doesn't know anything about snowmobiles specifically but he buys cars to fix up and sell so he's done things like head gaskets and such.

 

[i_play_bass]

POLARIS 99 98 00 XLT Triumph SPECIAL OEM OIL PUMP 3085877 4 Oiler Line | eBay

<p>Good used shape from a running 99 xlt POLARIS 99 XLT SPECIAL OEM OIL PUMP 3085877 SP38. Condition is "Used".</p>

www.ebay.com

This will work for the oiler line mod correct?

 

[Coolhand]

Yeah that should work. I can't remember the exact install on those but someone will have videos or instructions on it. That is the upgraded oil pump. I would also check and see if the drive shaft or w/e Polaris wants to call is the same as well it should be but always double check.

 

[i_play_bass]

Ok. So did some looking tonight. I didn't have time to tear off carbs or exhaust but I tried the wd40 behind the clutch while running and no effect at all. Not even an audible blip. Just normal idle. I even sprayed a little around the carb boot and nothing. Cant see any visible tears either.

Also strangely, I did another compression test right away cold and came up with 110 right across the board. Even in the cylinder that had dropped down to 90 on Sunday. I let it idle a few minutes and revved up a few times until the clutch engaged and wanted to move forward. Tested compression again and still all at 110. I know this is on the low end for sure. I did notice the o-ring on my compression tester that seals to the head is worn so I'll need to replace it but, even so, that should be giving me a lower psi if anything.

I'll likely run the borescope into the exhaust and carbs to take a look at the piston skirts, just saves me the teardown since I have access to it now anyway.

Why would I be getting 90 over and over on only that pto side cylinder 3 days ago and now getting a higher reading?

PTO:
View attachment 65672

CTR:

MAG:

 

[i_play_bass]

Uploaded a few videos of it running:

I do hear a bit of a knock when the engine revs drop again but full disclosure, my old clutch that needs a rebuild badly is still on it for testing because I couldn't get a mechanic to swap a new spider and weights into mine yet, so could be the worn clutch... Or something else, not sure

 

[TheBearAk]

temperature gauge is a good thing for Triples. Just point it at the exhaust manifold for each cylinder and temp differences can tell you which cylinder is running bad.

Amazon.com: Etekcity Lasergrip 1080 Non-Contact Digital Laser Infrared Thermometer Temperature Gun -58℉~1022℉ (-50℃～550℃), Yellow and Black: Kitchen & Dining

Amazon.com: Etekcity Lasergrip 1080 Non-Contact Digital Laser Infrared Thermometer Temperature Gun -58℉~1022℉ (-50℃～550℃), Yellow and Black: Kitchen & Dining

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[BC_Dan]

If you don't find any damage to the crown or the piston skirts, I would suspect a sticky ring...