96 ski doo formula sls 500 engine trouble - Snowmobile Forum: Your #1 Snowmobile Forum
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post #1 of 10 (permalink) Old 12-09-2009, 08:35 AM Thread Starter
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96 ski doo formula sls 500 engine trouble

Anyone familiar with this engine, doesnt seem to be in too many sleds, Rotax type 494. Just got it so dont know much history besides it was running when it cut out and guy hasnt touched it in almost a year but sled hasnt been formerly registered since 01. Its hard to turn over even without spark plugs so I took the engine out, pistons look ok excpet the one must have sucked something in cuz it has a bunch of little dings and chips on the top of the piston and head. The other piston is darker and seems to have a depression in the middle of it, either designed or its about to burn through. I see this engine has rotary valve which is cool I guess, but just more to go wrong. The disc has a good groove going all the way around but still seems to work ok. The engine turns over a little better now but still seems like a crank bearing or rod is rubbing and when I turn over the engine slowly the clutch makes a popping/pinging noise at least once a turn. I want to strip it down to the crank to get a good look but dont have experience in this area, only have taken off the jugs on engines before, plus its best if I have a manual to know how to put it back together correctly, where should I look for one?
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post #2 of 10 (permalink) Old 12-11-2009, 05:31 AM
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The pits and dings usually means thata rod bearing went on it and it sucked up bits of bearing. The difficulty in pulling it also would lean toward that. Separate the case halves and look at the crank bearings.

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post #3 of 10 (permalink) Old 12-11-2009, 10:25 AM Thread Starter
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Yea thats what Im gonna end up doing, I just bought a manual for it too
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post #4 of 10 (permalink) Old 12-14-2009, 04:15 PM Thread Starter
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Still waiting for my shop manual, but I took all of the bolts out of the engine, just trying to split it in two now, any suggestions? Do I need to take off the clutch or flywheel/stator?
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post #5 of 10 (permalink) Old 12-15-2009, 06:36 AM
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Yes you need to remove the stator because the bolts go into both case halves. You don't have to remove the clutch to split it.

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post #6 of 10 (permalink) Old 12-15-2009, 10:42 AM Thread Starter
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Do I need any special tools besides a 30 mm socket?
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post #7 of 10 (permalink) Old 01-19-2010, 01:36 PM Thread Starter
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So I finally tore down the engine to the crank, it wasnt that hard, I used a harmonice ballance pulley puller on the flywheel that thing wasnt budgging until I added a little heat then a loud pop and it flew off. My cases dont seem to bad just kinda sloppy machining. I see one of my outer bearing on the clutch side no long has its race so the 9 balls are just hitting eachother, that was the poping noise that I thought was the clutch. That bearing also moves up and down the crank, isnt it suppose to be a snug fit? Where do I go to get another crank bearing, I dont see those in the parts book or maybe I didnt look hard enough. Also on the clutch side my con. rod wiggles side to side a decent amount, more than the other side but I dont see any damage, wear, or missing parts.
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post #8 of 10 (permalink) Old 01-19-2010, 07:03 PM
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The Crank bearing # 6207 NRC4 .Side play on the rods is normal.
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post #9 of 10 (permalink) Old 01-22-2010, 06:34 PM Thread Starter
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Both of the outside clutch side bearings are bad, the plastic races fell apart. A local shop said I will need a new connecting rod as well since there is slight noticealbe up and down play as well, not sure if the needle bearing wore or the rod but I dont wanna pay to split the crank so I think Im just going to get a used crank.
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post #10 of 10 (permalink) Old 01-22-2010, 10:15 PM
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Those plastic cages were crap.If you get a used crank make sure it doesn't have the same plastic cages.
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