1996 Indy Storm 800 questions. *Update now 861* - Page 4 - HCS Snowmobile Forums

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Old 03-15-2010, 09:37 AM   #31 (permalink)
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QUOTE (Jesse Lackman @ Mar 14 2010, 09:22 PM)
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What bugs me about the purple heads is the wider squish pad and the deeper chamber. I think the the newer chambers are better but that is a gut feeling. One would think the chambers improved with time, not got worse. The ThunderDome conversion would be the best. It would be so easy to check heads on the dyno but I'm not set up for snowmobile engines - maybe a good summer project??[/b]
I've owned/worked on Storms since 93. The deep purple heads came on the 94, the lighter purple (pink) were 95, the red were 96 and up.

Up thru 95 all Storms had cast iron bores and relatively poor transfer port design, as well as numerous other deficiencies. They wouldn't produce even 200 hp in full mod form.

In 96, Polaris made many improvements to this engine. They went to nicasil bores, colliding stream transfers, sequential firing ignitions rather than simultaneous, better head design, etc, etc. By installing cast iron sleeves, you gave up some of the benefits of nicasil. (Better heat transfer, leaner jetting, tighter piston to bore clearances). You also should have gained some cranking compression because of stuffing more volume into the same size combustion chamber. But, apparently you did not because of the bigger cc heads. So, IMO, you need to get a set of STOCK red heads. Don't over rate the Thunder Domes. They were screwed up (wrong squish angle) on a 97 Storm that Legend did for a buddy.

The 95 Storm owners were offered to upgrade to 96 Cylinders and heads free of charge.

Personally, I believe you have a clutching problem(primary and possibly secondary), low compression and maybe a jetting issue. But first make sure you don't have too much belt side clearance or belt deflection as that will start you out with the weights too far advanced and it will act as if in "second gear". Also, you need to raise the compression to at least 125 using properly recut STOCK red heads to match the larger bore size.
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Old 03-15-2010, 05:39 PM   #32 (permalink)
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Thanks.

The 96 red heads are different from the 97 and 98 red heads. From the pictures I've seen the sparkplug seat area is even with the head nut seats like on the purple heads we have. The 861 Wiseco pistons have a step so the stock chambers don't have to be opened up. That reminds me of something interesting about the 35cc read head set I picked up - they were cut for a larger bore. So either they were on a stroker or a turbo machine, nothing else makes sense. Unless it was a low compression "top hat" mod? I can't find any info on that mod though.

Here's a shot of the piston in the bore, you can see the step that seems to be for chamber clearance;



I know there's too much side clearance on the primary clutch, plus I need to get the machine back to Polaris belts. 1065 seems to be a highly recomended one, I see others are too - 1075 is harder or something? Anyway I'm going to pick up the spider tool for the 4-Pro so I can science out the clutching.

I thought long and hard about sleeving the cylinders, and using Wiseco pistons, but that part of the project turned out well. I set the piston to cyl wal clearance at .0060

Pistons modified to help prevent the "four corner sieze";



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Old 03-15-2010, 06:30 PM   #33 (permalink)
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Another thing about the purple heads is the squish pad angle is 10 degrees which is about an exact match with the piston top. The 96 red heads have a 15 degree squish pad angle.
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Old 12-15-2010, 06:45 PM   #34 (permalink)
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Well I put a set of stock 1996 red 26cc heads on and it's like a completely different engine - no bog at all. Revs pretty freely now- will hit 8500+ very easily and would go higher. I think it would pull the 23/37 gears now. Or I need to read up on tuning the Pro-4.

That high rpm kind of scares me.
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Old 12-15-2010, 06:53 PM   #35 (permalink)
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Quote:
Originally Posted by Jesse Lackman View Post
Thanks.
plus I need to get the machine back to Polaris belts. 1065 seems to be a highly recomended one, I see others are too - 1075 is harder or something?
1065 is 12.5" c-c , 1075 is 12"
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Old 12-16-2010, 11:20 AM   #36 (permalink)
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The 075 belt number is a mistake, I got a 073 for it and put it on last night. Also put the recommended Comet Blue primary clutch spring back on. Comet recommends the Blue primary spring for the Pro-4 on Storms and the XCR 800s. Last season I put the orange primary spring from the old clutch on. I have no idea what brand spring it is, the wire measures .212" and it's free length is 3.95".

I have two A-2 and two A-3 weights on the clutch. It's supposed to have four 48.9 gram weights according to the Comet Pro-4 calculation, the A2/A3 combo is a little light at 46.5 grams (average). I don't know about mixing the clutch weights, if the weight shapes are different they won't act like a set will they? Looking at the Comet weight tables it's obvious some of the shapes are very different. I think I will put a set of four A-1s (48.5 grams) on, they are the closest to what the recommendation is.
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Old 12-16-2010, 07:23 PM   #37 (permalink)
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Well almost made a full circle today;

1) put the Comet blue primary spring back in with Comet A-1 weights off the line bog

2) put lighter A-2 weights in - off the line bog

3) put the A-2/A-3 weights on - still bogs off the line runs great at top end.

4) put the unkown orange spring in with A-1 weights - bogs but not as bad

5) put A-2 weights on bogs off line but not as bad and revs to 8500-8600.

I think what I need is a spring with more pressure @ 2.5 and the same compressed.

The Comet blue is rated 118 @ 2.375 and 187 @ 1.126

No clue what the orange is but has to be quite a bit higher on both.

Polaris blue is 120 @ 2.5 and 300 @ 1.19

Here's a polaris storm mutt that runs a 185-300 spring with no bog;



I don't want a 5500 engagement I think a spring like Polaris Almond/Gold which is 150/290 would work.

Also it could be a rich bog - I put Boysen reeds in it and the instructions say you might have to drop 1-3 main jet sizes. The bog happens when you hammer on wide open throttle instantly so I'd think the carbs are on the mains. But the spark plugs look good so I hesitate to drop the main jets just for the hammer on the throttle off the line bog.
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Old 12-22-2010, 12:10 PM   #38 (permalink)
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When we got this running last spring it developed a base gasket leak on the center cylinder. The coolant tank overflow tube was plugged and overpressurized the cooling system. Anyway this fall I pulled and fixed the center cylinder base gasket. A couple days ago the PTO cylinder base gasket let go so now all the cylinders are off and I ordered the Cometic rubber coated metal base gaskets. I don't know why Cometic wouldn't include those in their sets when the paper ones have a history of leaking. The cylinder bases are flat, in fact the corners of the gaskets right under the base nuts are the first to start sticking out.

For any reading this I'd say don't bother bolting a cylinder on with a paper type base gasket. Original Polaris paper type seems to have a better reputation than Cometic but there's no way one of the rubber coated metal ones will break up and fail like the ones on this engine have. I wonder if harmonics has anything to do with the base gaskets breaking up.

Do you guys loctite the cylinder base nuts??
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Old 01-10-2011, 02:28 PM   #39 (permalink)
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It's running again with Cometic rubber coated metal base gaskets. Compression is 130 on all three. Engine runs very well, clutch tuning is driving me nuts.

We started with a Polaris blue 120/300 and Comet A-1 48.5g weights. engagement rpm was around 3700, shift out RPM 8500. Instant WOT bog.

Installed a Polaris Almond/Gold 150/290. Weights were the Comet A-1s. The engagement RPM was up at around 4000, shift out RPM seemed to stay around 8500. Still have the instant WOT bog.

Next we tried a set of Polaris 10MB weights these are 47.5g weights so you would expect the engagement RPM to go up right? Well it went back down to around 3800. Part of the problem is that the Polaris weights "preloaded" the movable face on the Comet Pro-4 by almost 1/16". So not only did the engagement RPM go down (with lighter weights), the movable face was closer to the belt - kind of a double whammy as far as curing the instant WOT bog.

I think I should stick with Comet weights but there are so many profiles, some like the A-21 through A28 have a notch at the rest position which apparently will raise engagement RPM and increase the engagement hit. I have A-1s, A-2s, there is an A-1 "mod" that looks interesting - it's profile looks shallower at the pin which might help the bog. The A-1 "mod" weight is 47.3g. Remember there are four weights to a set on the Pro-4.

There's a Gold spring in the secondary, in the tightest position, and the helix is a Polaris R-3 (45/32).

Here's a picture of a weight with the rest position cut out like the A-21-28 Comets; clutch weights for comet clutches

My plan is to try the Comet A-2 (48g) set next.
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Old 01-10-2011, 06:46 PM   #40 (permalink)
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Man, it's almost there! The A-2s are in , engagement is about 3900, shift out is still about 8500, that's the highest RPM I see. I could probably try a Polaris Almond/black (165/310) or a Almond/Red (165/310) and deal with a higher shift out in the secondary.

If you're at 4500 RPM and nail it - wow. If you are at idle and nail it there's a bog about 4000-4500 - then wow.

Tried the jet needles one richer and one leaner, leaner is better. I think I need to drop one or two main jst sizes. The plugs are a dark brown. Jetting is 380-380-400 now.
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