1996 Polaris Indy Storm 800 questions.

We just bought this sled from our son. I've been away from snowmobiles since the early 80s and this kind of sled is all new to me - it's nothing like the MF Ski Whiz I used to have.

First some information on the sled; Model 965782 and says Storm 800 on the hood. The "RMK" "SKS" etc acronyms are confusing to me, but apparently this sled is one of those in addition to being an Indy Storm 800. The sled was based in the Sturgis SD area. We could not get it started but brought it home and put it in our heated garage. I did a compression test on it before I tried to start it here;

L-75 M-60 R-48 (cold closed throttle)

I got it running and after it was warmed up;

L-75 M-68 R-64 (hot closed throttle)
L-100 M-75 R-64 (hot open throttle)

I pulled the carbs and noticed the main jets were L-330 M-330 R-350 with the jet needle c-clips in the lowest position. The label on the hood said the jets for 0-3000 ft and +10F-+40F should be 380-380-400 and the needles in the #3 position (I was told #3 is the third down from the top). So I put the carbs back to those specs as we are at 2000ft here. The air filter got replaced and also the line from the oil tank to the oil pump as it was squished somewhat flat. I drove it after those changes and it seems to be boggy in the mid range in deeper snow - not like a rich condition but more like a clutch downshift problem. It would seem to get "stuck" in the 5500RPM range and couldn't pull out of it, again like the clutches were "stuck" in their max ratio position. It does run much better without the midrange bog on hardpack. I wonder if a gear change might be in order - I'm not after ultimate top speed. The spec sheet on the hood says it should have a blue primary clutch spring. It has a red one instead. What I found online was that the Polaris red spring has less tension than the blue which leads me to wonder if it is engaging and shifting below the engine's power band. I have no clue if the clutch weights have been messed with because I haven't had them off.

This morning I did another cold compression test;

L-60 M-55 R-35

So it looks like this sled will need pistons and maybe cylinders. The Polaris dealer didn't recommend Wiseco pistons - does anyone know why that might be? They said something about expansion and Wisecos being more likely to stick than the OEM Polaris pistons. Also I see that Wiseco has 861cc sleeves, is sleeving these cylinders easy to do? The Polaris dealer said this sled has nickasil cylinders which they implied are practiacally industructable and I should only need new standard sized pistons, but I read that the 861 big bore "really wakes up the 800". I'm kind of a gearhead so that appeals to me.

First would be tuning the clutch I'd think, the engine starts and runs pretty good considering the low compression and we don't really want the sled down long term right now - we live in the country and might need it to get out if it snows any more. I bought an e-book on clutch tuning/rebuilding from ponderayyahamamotors.com, looked like a good one.

Any comments or suggestions would be appreciated, thanks.

Thank you. It's got 4200 miles, I knew cylinders and pistons were a possibility when we bought it. I was just out and it started with two pulls, it was inside though, it really does run pretty good, actually the power is scary compared to that 1971 Ski Whiz.

Warm today the compression was L-60 M-60 R-60.

I have two stroke stones for my Sunnen hone but it sounds like those nickasil bores don't always need honing - is that your impression?

theultrarider said:

Bingo...It is next to impossible to get a 2 stroke to run under about 80psi..get under 100 and they are very hard to start. Try another compresson guage.

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I know about low compression and hard starting, I used to start that Ski Whiz with an electric drill. :face-icon-small-ton This Polaris starts as good as I could ever expect it to, cold tonight two pulls, idles great.

The tester did seem to have a problem - like the tire valve thingy was restricting the air in, put a different one in and it read shop air close. Rode the sled some more, it's running a bit better, hard pack runs very good, will run in the deep snow around here at 5500-6000 or wide open - nothing really in between. After the ride the compression test was L-100 M-80 R-70. Looking through the spark plug hole I can see a slight amount of mechanical damage on the right piston top but no huge gouges in the cylinder walls. The air filter/screen/whatever it's called had an open hole on the right side that's why I replaced it, maybe something went through it into the right cylinder sometime. I read where someone recommended a 21/39 gear set for a stock Storm 800, I think the stock gear set is 23/37.

No more work on it for the next few days, we are leaving to nurse our college daughter after she gets her wisdom teeth chopped out tomorrow.

Thanks for the comments.

BB454 said:

You can run pretty tall gears at you elevation. 21/39 were probably about stock. That's 1.85 ratio, the 23/37 is 1.60. I wouldn't go that tall. It will be hard on belts in the powder. After you get it running. you may want to go to the R11 helix. It is a duel angle instead of a triple and seems top work better.

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It's got 23/37 gears we checked, I think I'm going to try the 21/39 gear set first. What we have here is pretty rough riding probably 70%-80% 10-30 mph with the balance more open and higher speed. The gears in it now are like driving around town in our LT1 TransAm with it stuck in fourth gear, you have this constant itching desire to shift down - but you can't!

What kind of tools are needed to change the primary clutch spring and rebuild the primary clutch? I think I need to go back to the blue primary spring.

R-11 helix in the secondary, stock is a R-3 that seems like a big change to me, I've been trying to find a chart of the various helixes and what they do, I did find good charts for the primary spring weights/springs and secondary springs.

Do secondary springs get weak over time?

Do these ever develop intermittent ignition problems, like a bad wire or coil? Spark plugs always look very even maybe on the rich side, I know the low compression could make the right cylinder flaky but it does seem that a cylinder drops out now and then, that's what my son said and he would have known how it used to run. Still starts, idles, and runs very good in my opinion, all pipes get hot right from a cold start and stay about the same temperature.

I'd think the knife-edging problem has something to do with not enough radius or chamfer on the bottom of the sleeves.

~

The 21/39 gears are quite a bit better but we pulled the pipes and looked in the exhaust ports, the top ring is broke and gone on the exhaust side of the middle and right cylinders.

Middle cylinder;



Right (recoil side) cylinder;



So now I know what I need to do.

1) Cheap route; try and cobble together three decent nicasil cylinders and new eBay SPI pistons.

2) Middle route; If older cast iron sleeved cylinders fit the '96 crankcase buy a set of them, do a mininum overbore with new pistons.

2) route; Put the cheap/middle route money into 861 sleeves / pistons.

Hmmmm....

Hey!

We got this Storm running again a week or so ago. This is what we did;

• Wiseco 860cc pistons
• LA overbore sleeves in non-sleeved 1996-1998 cylinders
• port and sleeve cleanup and matching throughout
• Boysen reeds
• stock pipes (bought a set of PSI modblasters but there was no way they were going to fit under the hood without cutting it up.)
• new comet 4-Pro clutch
• weird 1996-1998 red cylinder heads that are 35cc (stock are supposed to be 26cc)
• Cometic single layer head gasket (.011 thick)

The bog at 5000-5500 is still there. It will get stuck at that RPM even at WOT. Yesterday I got it to bog at 5500 WOT, then killed the engine and pulled the plugs - they were nearly black, but not wet. If you are careful to keep the RPM above 6000 and out of the bog the plugs look great, a dry creamy coffee brown.

We have sets of Comet A-1, A-2, weights. engagement RPM with the Comet blue spring was never over 4000 so I put the orange spring from the old clutch in. With that orange spring and a combo of two A-2 and two A-3 weights the engagement RPM is 4500-4600. The orange spring is not a Comet or Polaris orange spring. I think I'm going to order a Comet purple spring. I think it would help some to have te engagement RPM more like 5000+. The Comet blue isn't going to work at all, the orange spring is unknown, (the wire dia of it is .212 the free length is about 4"). I need to be working with known springs. The secondary spring is a stock polaris gold, in the heaviest position, the helix is an R-3 (45-32) I've read a straight 36 would be better.

What's especially frustrating is that from idle we can nail the throttle to wide open and the sled just boggs - won't even spin the track. My gut feeling is it's too rich in the 1/3-1/2-3/4 throttle range. I've tried dropping the needles two slots (they are at #3 stock) but it hasn't cleared the bog. I don't think the 35cc heads help at all, the CR with them is about 9.4. I think the CR at 11 with normal 26cc heads would make a huge difference. Those heads must have been on a turbo sled, can't imagine why else anyone would machine 9ccs out of stock heads.

Timing is at about 17 BTDC @1600 RPM idle which is about perfect. Never checked it at 8000 like it says in the service manual. Too scary. I did order a new CDI off eBay - do the CDI boxes ever go bad?

Do the Mukini needle jets ever wear to a larger diameter? This sled has 5000 miles on it, should I replace the jet needles and needle jets? I dont' think the bog is a main jet issue because over 6000 it runs real clean and good. In other words it's not too rich when on the main jet over 6000 RPM.

Oh, the compression is about 95-100 on all cylinders - that's because of the 35cc chamber heads. I didn't know they were 35cc when I bought them - seller didn'tknow it either and has no idea what they were on.

35cc red head, 26cc purple heads, notice the spark plug height lower in red heads, red heads have a shallower chamber;





26cc stock red head;