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Xrs_800
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The over heating issue with the beaver tail delete is an issue without a heat exchange swap also. If the trails are hard packed it will over heat with out scratchers

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I agree without a heat exchanger swap you could have problems after the beaver tail delete. Good snow conditions, probably fine. Low snow or icy conditions, maybe not. Seemed to be the 600’s faired better than the 800’s but lots of guys ended up swapping in longer coolers. I’m sure lots of guys didn’t either. On our 2003 600 the chassis and skid had some issues so I rebuilt the sled on a 2005 x package frame. Personally I don’t think these sleds will ever reach high dollar collector status.
 

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Riding hotter days like 0-10C (32-50F) does it too, unless the speed picks-up. Note how water drips from the heat exchangers, yet it is still overheats at lower speeds. It is difficult to pick-up speed when having to get through a mile of tight trails in a dense forest. Can't just kick back in the loose stuff when the trail barely fits between two trees. Hard to goose it when there is a sharp bend every 100 feet. The temps keeps climbing, 160-170-180-190-200F..... This is one of the paths to buying a 4S. I am not kidding. Note how four strokes operate a higher engine temperature. They have an added cycle for cooling, and they don't use o-rings to seal the head. Heat is the enemy of a 2S.
 

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I agree without a heat exchanger swap you could have problems after the beaver tail delete. Good snow conditions, probably fine. Low snow or icy conditions, maybe not. Seemed to be the 600’s faired better than the 800’s but lots of guys ended up swapping in longer coolers. I’m sure lots of guys didn’t either. On our 2003 600 the chassis and skid had some issues so I rebuilt the sled on a 2005 x package frame. Personally I don’t think these sleds will ever reach high dollar collector status.
On the bold, I tend to agree. One of the main drivers of sled collectibility is how rare a sled is or was. I realize how revolutionary the 2003 REV was in terms of sled design, and whatnot, but one thing the 2003 REV never was, is rare. Doo sold as many of those things as they could. Even with the attrition of sled getting wrecked and parted out, there are still a lot of 2003 rev chassis sleds kicking around.

Sorry for the hijack. Maybe we can get an update from OP???
 

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On the bold, I tend to agree. One of the main drivers of sled collectible is how rare a sled is or was. I realize how revolutionary the 2003 REV was in terms of sled design, and whatnot, but one thing the 2003 REV never was, is rare. Doo sold as many of those things as they could. Even with the attrition of sled getting wrecked and parted out, there are still a lot of 2003 rev chassis sleds kicking around.

Sorry for the hijack. Maybe we can get an update from OP???
I truly hope that you are right, because parts for these old engines are growing scarce by the year, and in some cases by the hour.

For the revolutionary REV in 2003 is most definitely what I am referring to. Even if there was 1000 of them left in great condition, the chances for a low mileage one decreases exponentially. You and I are fortunate to see one show up on DooTalk, as this is only the second one since 2017!
 

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Discussion Starter · #26 ·
Update you want? Update you shall get!
Tonight was the night to spend a few hours in the shop with the sled.
I had already confirmed that the sled wasn't getting fuel, and wouldn't start. I figured the carbs needed attention, but before tearing it apart, I figured I'd do a compression check.
Left hand cylinder 120 psi, meh. Right hand cylinder, 60 psi. omg.
Using a boroscope, I inspected inside each cylinder. Both looked great. Bright, shiny, crisp cross-hatching on the cylinder wall, no obvious signs of damage.
After a series of deep breaths timed with occasional shoulder slumping, I added some oil into each cylinder to refresh the ring seal and tested compression again.
Left hand cylinder > 150 psi, Right hand cylinder > 150 psi. <pheeeeeew>
Now on to the teardown.
Carbs came off fairly easily and I instantly found the delaminated boots. They were toast, and definitely would leak air at the 12:00 location on both boots.
I pulled the bowls off the carbs to see what I was in for. Hmmm- they were empty. And clean. And the floats moved freely as did the needles. This was a good sign. The P.O. must have drained the bowls before long-term storage.
My intent was to completely disassemble the carbs and run them through my ultrasonic cleaner to get them completely cleaned. But to do that I need to remove all plastic and elastomer parts. That would be a chore, and most certainly cause damage to at least some of said elastomer parts. I might get away with a thorough spray/blow out clean, remove and clean jets, and replace. <optimistic>

but... why no fuel?
With the line that supplies fuel to the carbs inserted into a bottle, I hit the starter on the machine to see if I could pump some fuel. Nothing.
<10 minute interlude to learn about Ski-Doo engine impulse driven fuel pumps>

Next place to look was the fuel pump. Should be pretty easy to pull that off and inspect, right?
Holy crap.
Getting that pump out was a bear! I did finally get it out, however.
Upon inspecting it, I found that instead of diaphragms, meshing gears, or some other means of displacing fluid, my fuel pump uses 'magical yellow jelly' inside to do its job. I don't know exactly how it works, but it must work well because there sure was a lot of it! :-D
Sure enough, the residual fuel in the pump had gummed up, and was clearly causing an issue. I checked the fuel supply line from the tank, and aside from a few goobers, it was running clear.

Soooo- next up: buy new fuel pump.
Mine is an electric start, so I believe I need p/n 403901808 .

Do you guys have any favorite places to order OEM parts?

Thanks for all the help fellas, as well as the entertaining discussion. More to come!

Bob
 

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Sounds like you’re off to a good start. Might be worth removing the fuel tank to give it a thorough cleaning. I wouldn’t be surprised to see the line inside the tank is in poor condition, as well as the grommet where the line goes into the tank. Your compression test results lead me to believe you have the famous ring flaking issue. Perhaps you could remove the expansion chamber and use your borescope to inspect the rings through the exhaust y-pipe. I’m betting you will see the flaking. It’s not a hard job or expensive to remove the cylinders and install new rings. At 3000 miles there’s a good chance the pistons are still in great shape. As for oem parts, I try to support my local dealer as it’s in my best interest to have them stay in business.
 

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Discussion Starter · #28 ·
Sounds like you’re off to a good start. Might be worth removing the fuel tank to give it a thorough cleaning. I wouldn’t be surprised to see the line inside the tank is in poor condition, as well as the grommet where the line goes into the tank. Your compression test results lead me to believe you have the famous ring flaking issue. Perhaps you could remove the expansion chamber and use your borescope to inspect the rings through the exhaust y-pipe. I’m betting you will see the flaking. It’s not a hard job or expensive to remove the cylinders and install new rings. At 3000 miles there’s a good chance the pistons are still in great shape. As for oem parts, I try to support my local dealer as it’s in my best interest to have them stay in business.
Thank you for sharing your insights!
Great suggestions. Assuming the sled is on its original pistons and rings, it may not be a bad idea just to replace both while I have it taken down this far. Just a thought. Any favorite piston/ring combos should I go that route?

Thank you again!
Bob
 

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Myself I am a fan of the OEM pistons and if they were in good shape I would probably choose to replace the rings with oem parts. If the pistons are damaged than the cost of oem replacements gets quite high. At that point a better option might be replacements from a site sponsor like MCB Performance.
 

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Ford hater
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Id be worried about the low compression that only fixed itself with oil, sounds like a flaked ring. I’d def dig into that


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Before you take it further apart, you need to do a leak down test. See if it holds pressure. If not you have leaking seals someplace. Pull off the clutch and see if the crankseal is in place. Also inspect the y pipe. Pull off the insulating covers and throw them in the trash. Y pipes are always cracked on these.
I had a 2003 that after each season had some engine issues. Replaced pistons, then clutch side seal, then another piston, then center crank seals. Rather than chasing issues, I traded in the engine on a skidoo rebuild and never looked back.
Financially I put toys in a different category than other transportation. I figured if I put the $1500 in a new engine, rebuilt the shocks and clutch, newer used track I would have a fresh sled. There is no way I could buy another used sled for that same price that was guaranteed to be as fresh.
That sled now needs a new nun, with around 10k miles many folks would say it’s not worth it, but I have no problem throwing money into it. I couldn’t buy a replacement for the same price and I know it’s history.
At some point I will give up on it, I finally let the old Polaris wedges go, but the REV platform is still a nice riding sled.
 

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150 psi on both cylinders is fantastic news! This means no obvious need to replate the cylinders. Take a close look at the main exhaust port chamfer to make sure both sides look even. You may even get away with only a set of rings. The crankshaft is a no brainer. They are not expensive and worth every penny.

If you want to avoid the pitfalls, let us know before tearing into the engine. In case you do go too quick, make sure to drain all of the coolant and finish the drain by removing the lower coolant hose at the front of the engine. Hopefully any work gets done with the engine on a bench.
 

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Discussion Starter · #34 ·
150 psi on both cylinders is fantastic news! This means no obvious need to replate the cylinders. Take a close look at the main exhaust port chamfer to make sure both sides look even. You may even get away with only a set of rings. The crankshaft is a no brainer. They are not expensive and worth every penny.

If you want to avoid the pitfalls, let us know before tearing into the engine. In case you do go too quick, make sure to drain all of the coolant and finish the drain by removing the lower coolant hose at the front of the engine. Hopefully any work gets done with the engine on a bench.
Hi guys-
Couple of thoughts/follow ups...
  • Leakdown test isn't a bad idea. I see a number of threads on how to cobble a kit together with some PVC fittings. I'll install the new reed cages and boots, and will then give it a go.
  • In that the engine had been dry for 9 years, it wasn't a surprise to see the compression jump with the addition of a little lubrication. That didn't seem abnormal to me, but I'll continue to investigate given the known issue.
  • I will look at the rings through the exhaust port after leakdown.
  • After removing exhaust components, what do you guys typically use to reseal the joints? I have a thin uniform layer of what appears to be high-temp silicone (red) between the silencer and mid-pipe now.
  • Daag, my plan wasn't to pull the engine. I'm not sure that's necessary quite yet. I'd love to come back with news that the rings have already been replaced, and that the leakdown passes. At which point I'll button up the top end. If rings look suspicious, they'll get replaced, judgement call on the pistons.
  • Daag- you mention crankshaft. Are you suggesting that replacing it is a no-brainer? Can you say more about that please?

Many thanks to all. You guys are awesome.

Bob
 

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I am glad that you are taking the steps to build an engine leak test and willing to ask the questions. I am familiar with everyone on this thread who I learned a great deal from. The differences we hold is a blessing.

For the building of an engine leak test kit, it may appear to be cobbling out of PVC, but this is as real as it gets. You will likely find leaks all over the place from the intake to the y-pipe. This part will take some work.

The compression rising with adding oil was to be expected with flaking rings, and to be expected with a 2003. Start with the leak test as this needs the y-pipe to get done more easily.

For the exhaust components, the high temp sealant at the local auto parts store (typically red) works perfectly for any joint. For the y-pipe gasket I coat both sides.

For working on the engine in place versus on a bench..... It is often done in the engine bay, but cannot fathom doing my best work this way. I also won't remove an engine without the appropriate hook unless I am in some sort of bind which is rare. That is something to figure out for one self.

For the crankshaft, I meant both. As long as you know the pitfalls ahead of time, the lower end is the easiest part of the engine build. As a comparison, filing rings down and figuring what spec to use is the most complicated part of the rebuild. Heck, installing the wrist pins and fitting the jugs over the rings is far more difficult then assembling the lower end. The exception is on a sled that has had a top end failure or high mileage. Then you need to scratch your head on what to do with the center shaft. The other part of the no brainer was making the choice to replace the crankshaft.
 

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If you want to get a “better” idea on the ring situation, get the sled running and up to operating temp. And see how it idles, does it go into RER and back to forward without stalling. And how is hot starting.

Give it a couple running sessions and then pull the plugs and get a compression reading. I’d be highly suspect on the cylinder with low compression earlier


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Could also explain why the sled hasn’t run in 9 years, it went down. Got parked, and the guy bought a new sled


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My pressure test story, trials and tribulations. I naively plugged the y pipe, intakes, fuel pump pulse line and added air. I had leaks everywhere. There were just so many things to fix. The seal between the y pipe and cylinder leaked, the y pipe had a crack, didn’t pinch the pulse line tight enough either. Went through a bottle of soapy water that first trial.
Ultimately I removed the y pipe and made a block off plate and rubber gasket from a old inner tube and tested each cylinder separately. Pumped up the clutch side, watched and waited, then the recoil side.
Then pressurized the water pump cavity.
Fewer places to leak, easier to find. Saved me lots of time.
 
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