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Engines and Mufflers Having problems or need advice on Engines or Mufflers?


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Old 12-31-2010, 09:39 PM   #1
TTRAPTOR903D
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Exclamation Sand Liner or Replace 91HZ

I had a lean run today after changing nitro % to 30 from 15 . I had good smoke , Now ruined piston, my liner has slight scuff but cant feel it with fingernail . . Is it ok to re-piston and just sand liner with 500 grit if there are no score marks? Do liners change shape or warp from heat? It will be my 1st overhaul. Trying to save money if poss considering I just ordered HZR for another 700 yesterday.. ARRRGH
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Old 12-31-2010, 09:43 PM   #2
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Liners are tapered. I would not sand it. Take a little Muiriatic acid on a Q tip and swab the alum scuff away. Muiriatic eats Alum.

You might get lucky, with just a piston.
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Old 01-01-2011, 10:45 AM   #3
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I may be incorrect, but I've never seen a ringed engine with a tapered liner. The ring does the sealing. Now a engine with a ring-less piston does need a tapered liner as the piston makes the seal.

I'm a mechanic in a power sports dealership. Last year we were having some issues with 800cc snowmobile engine. The pistons were scuffing. We were instructed to replace the cylinders if there was any metal transfer from the piston to the cylinder. If after honing it we were left with a "stain" that could not be felt the cylinder was OK to use. These cylinders are plated with Nikasil. We used a standard hone to hone them (just to "clean them up") as instructed by the MFG. It you want to remove any material, you must use a diamond impregnated stone.

Now with the above said, Most of our engines use a chrome plated sleeve. IMO, never use any kind of sand paper on this sleeve. I would use a red Scotch Brite pad. Just clean it up and scuff the surface a bit to provide a new surface for the ring to seat in.
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Old 01-01-2011, 11:28 AM   #4
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OOh Ya oops, I never saw the size. Ya ringed won;t be tapered. I was thinking smaller Glow engine

Which brand are you a dealer with? I am Skidoo faithfull here And ya we've had some issues with pistons a few years back
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Old 01-03-2011, 07:54 AM   #5
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Yamaha, Polaris & Artic Cat. The Polaris's are the problem children. Looks like it may be starting again this year. IMO it is piston clearence. Not to tight as you can almost jump in beside them they are so loose. We are seeing 100/105 PSI for compression on sleds with only 100 or so miles on them. I would want to see no less that 110/115 and 120 would be better.
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Old 01-03-2011, 08:23 AM   #6
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Originally Posted by kenh View Post
Yamaha, Polaris & Artic Cat. The Polaris's are the problem children. Looks like it may be starting again this year. IMO it is piston clearence. Not to tight as you can almost jump in beside them they are so loose. We are seeing 100/105 PSI for compression on sleds with only 100 or so miles on them. I would want to see no less that 110/115 and 120 would be better.
HUH?
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Old 01-03-2011, 11:19 AM   #7
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Quote:
Originally Posted by kenh View Post
Yamaha, Polaris & Artic Cat. The Polaris's are the problem children. Looks like it may be starting again this year. IMO it is piston clearence. Not to tight as you can almost jump in beside them they are so loose. We are seeing 100/105 PSI for compression on sleds with only 100 or so miles on them. I would want to see no less that 110/115 and 120 would be better.

OOH Damn Buddy just traded his Problematic '10 Dragon off for a 11 Pro RMK. He had 3 motors last year in the Dragon. Wonder how many this year LOL


Sorry OP, a little sidetracked on this post.
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