Well after a few rips around the fields and yard the other day, some slow-mo joy-rides around the yard with my 4 & 7 yr old nieces yesterday, and some wide open laps around the field today...the sled was starting to act funny. These past couple days have been my inaugural riding with this sled, as this is the first snow. Bought this initially for its
Engine for a buggy, but decided to test out the powerplant since we've got 5-7" snow laid.
Initial Symptoms:#1. I'd use the brake...and the Engine would want to die.
#2. Try to start it...and the gearbox would engage = belt has tension
#3. Did not want to start due to the tension on the belt (starter was driving the track), and killed the battery trying.
#4. Still pushing out 165-169psi compression in both cylinders.
#5. Clutches were lubed on day #1 with some dry-moly lube.
I opened the hood and checked the driven clutch. Looked good. Looked at the primary clutch and the belt was juuuuust barely catching, as if the clutch had not fully disengaged. So my initial diagnosis was a
stuck primary clutch. Pulled the battery and put it on the 10A/30min quick-charger.
Took the plug wires off to get to the plugs. Noticed the left bank was running a BR8ES and right a BR9ES. Not cool. Embarassed I never noticed it. Left bank was dry and look a tad lean. Right bank looked normal and slightly wet. Also noticed some carbon build-up on the left bank exterior near the clutch. Installed two new plugs, and freshly charged battery. Managed to get the sled started and drove it back into the shop. Parked it.
With the Engine still warm, ignition off, and airbox off, I rotated the primary clutch around by hand to see the belt engagement. Sure enough, the primary was about 1mm away from disengaging the belt. As I was rotating the clutch around, a few puffs would come out of the carbs as some fuel was hitting the hot chambers. BUT THEN...I noticed a small puff out of the corner of the base gasket of the left bank jug. AIR LEAK! =(
At this point I was worried about a fried cylinder AND a stuck clutch. And I knew I was going to be pulling this Engine.
Four hours, 4 cups of coffee, and several episodes of Overhaulin' later, the Engine was out (single-handed-ly) and I was VERY VERY VERY surprised at how easy and straight-foward the Engine removal was despite having no shop manual to reference. Kudos to SkiDoo and Rotax! No stuck bolts. Everything came apart nice and looked clean for being 22 years old. Only weird thing was the jug base bolts seemed loose. It took very little effort with the 3/8" ratchet to loosed them. Not torqued? Not heat-cycled and re-torqued? Muffler box has some cracks on top, but very fixable. The left side airbox-to-carb boot is torn and poorly jerry-rigged with vinyl tape (sigh). Suspension bellows are tattered and letting snow into the Engine bay. Rotary intake is very clean and smooth.
Laid out all the parts and got the Engine on the bench.
I verified the failed base gasket on the left bank base. Gasket is toast. Both cylinders looked great and cross-hatching was still visible. Head chambers are clean and smooth. Pistons had only a couple marks that appear to be gasket or gasket sealer smudge marks. Left-side measured 2.726" P-OD @ 2.735" C-ID (.0045" WC). Right measured 2.725" P-OD and 2.735" C-ID (.005" WC). Upon inspecting the rings, I found a sticky lower ring on the right bank. Have yet to feeler-gage the ring grooves. Grooves need cleaned first since there is a bit of carbon in there.
Got the clutch bolt off with the assistance of some leverage, but couldn't find my clutch removal bolt. Bagged the Engine and called it a day.
Plans:1. Order a new top-end seal kit w/ crank seals (ORDERED, $39)
2. Find a manual for this thing.
3. New piston/ring kit, 69.5mm @ 2.736" bore (ORDERED PAIR, $80)
4. Get clutch off and apart. Hoping its fix-able, or hope one of my extras fits it.
And while I'm waiting for parts...
5. Clean carbs while they're off
6. Weld a piece of sheet over the muffler cracks.
7. Clean up the exhaust and paint with high-temp ceramic paint.
8. Clean out all the muck at the bottom of the Engine bay.
9. See what I can make as a replacement for the suspension bellows (Don't want to buy new since this sled is intended to be an Engine donor for my Rotax buggy).
10. Bead blast the jugs and head exterior.