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Discussion Starter #1
OK, I know: Curiosity killed the Cat... But I just had to look, especially after the little "gift" I received from AC yesterday. Here's the scoop:

1. Late build Std. F7 with 940 miles to date.
2. No enhancements.
3. All updates completed.
4. Recommended break in procedure performed w/ premix.
5. 90 - 92 octane fuel used. (ethonol mode on)
6. AC synthetic APV oil used.
7. Warmed up before riding.
8. No warning lights displayed.
9. Compression at 120+
10. Runs great...Absolutely no problems....

Except for the light scoring towards bottom of both pistons. So, what do you guys think?

A. Sounds like normal wear, dont worry about it.
B. Get out the sandpaper like the AC service manual suggests.
C. Order new parts while their hot.

Like I said, thing runs great, NOW. Don't have a clue what this scoring might mean for the future. Any thoughts are appreciated. Thanks and safe riding.
 

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Run it till she blows,if you make thru the winter great,then have them replace the pistons and cylinders this summer while you still have a warranty!!! :unsure:
 

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its under warranty get new piston and cylinder.thats what i did .had a scratch on piston and blow bye. :D
 

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I want to mention again that the photo of that piston is a bit decieving. The digital camera is picking up detail on the aluminum that is not visible to the naked eye. In essence, that photo is a MAGNIFIED view! There is NO scoring on that piston and it looks new to the eye. The discoloration is from oil and is smooth to the touch. You can't feel it at all. It is ok and nothing to worry about. Also, it was put there with some rather extreme oil testing. You guys get the idea. Also the sled was run at the "edge" on being lean, there is no piston wash at all (not good). But it was fine for that motor as it was being run. (Don't try that at home!) Still a good photo for instructional purposes. The oil marking is due to the uneven heating and cooling of the piston during use, 25:1 ratio etc. Kind of neat to see how the pistons heat and cool, where the hot spots are etc.
 

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My F7 Snopro has ~ 800 miles and has 150 lbs of compression in each cylinder measured by a Snap On Compression gauge using 5 pulls to check each cylinder: engine cold ~ 50 degrees F (heated garage temp). :)
 

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Discussion Starter #11
Is 120+ compression acceptable for these machines? Does anyone know what AC states as an acceptable range?
 

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Whent to the dealer with mine,scuffed piston's but didn't think that ac would cover it, not scuffed enough,now what do you think off that,if scuffed any at all wouldn't you think that they should be replaced????
 

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Thats what i was wondering, at what point and who makes the decision as to what is considered a scuffed or scored piston that qualifies for warrenty work? The mechanic? The consumer who knows about such things? Arctic cat?...and how would they get unbiased opinion as to the condition of the pistons? Anyone run into any problems with their dealers when they felt they should get warrenty work?
 

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My compression with a Mac tool tester at room temp is 145/145....I have what they call a good one. :D ...OH and that after 1045 miles to date..
 
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