Lower top RPM - HCS Snowmobile Forums

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Old 03-19-2012, 10:14 PM   #1 (permalink)
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Default Lower top RPM

Hey guys,

The last few rides i noticed the top RPM's reached isn't as high as it used to be. If i went WOT before the rpms would shoot up to 8400 and then settle out and hold 8200. The last rides it just shoots up to 8200 and then settles back to 7800 -8000 if i'm lucky. I thought it was the belt, so i put on my new spare. it's the same thing, the thing i noticed is that the dealer supplied spare belt is the 321115 belt and not the 321122 belt that came on the machine. From my understanding the 321115 belt is a cheaper belt, and when i adjust the proper belt deflection , it sits much lower in the secondary than my old 321122 belt.

Should my sled have come with the proper 311122 belt as a spare?? thats supposed to be there high performance belt. Any suggestions? Other than the belt nothing has changed except for the temp here warmed up from about -20 to about 0 degrees celcius. Would temp make that big of difference to the top rpms?
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Old 03-20-2012, 09:19 AM   #2 (permalink)
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The 115 is the more expensive and more durable belt which should have came on your sled. I am willing to bet that the previous owner put miles on the 115 and swapped in the 122 as a cheaper alternative. This is of course if you bought the sled used.

Are you sure that the "new" spare 115 was actually new?

Temp and snow conditions may also be a factor.
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Old 03-20-2012, 11:25 AM   #3 (permalink)
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Sorry i messed up the belt numbers in my first post....the 115 belt was the original that was the better belt, the spare was the 122 which seems shittier, it even feels like a cheap belt in your hands. I bought the sled new, is it a common thing for the spare belt to be of lesser quality or did my dealer swap it out so he could sell the better one??
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Old 03-20-2012, 01:17 PM   #4 (permalink)
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the 115 is a harder belt so a raise in rpm may be normal.
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Old 03-20-2012, 01:38 PM   #5 (permalink)
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I would say its more common to not get a spare belt at all....

I found with my 115 I was hitting 8250-8400 with a new 115 and after around 800-1000 miles i was starting to see a drop in RPMs so I swapped to a new 122 i had laying around and went back 8250-8300. Doesn't ever seem to rev like it did with a new 115. Next year I will be buying a new 115.
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Old 03-20-2012, 07:16 PM   #6 (permalink)
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The 122 is softer and would lower the RPMS a couple hundred, I tried both belts and have had good luck with both.
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Old 03-20-2012, 07:26 PM   #7 (permalink)
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if its softer and lowers the rpm, your missing out on the peak horsepower
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Old 03-21-2012, 06:45 AM   #8 (permalink)
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Quote:
Originally Posted by mbwhite View Post
if its softer and lowers the rpm, your missing out on the peak horsepower
Assuming that your not over revving with the harder belt! Which mine was. My plan next year is to run the 115 and weight the primary to get RPMS down to 8250.
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Old 03-24-2012, 08:00 PM   #9 (permalink)
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Quote:
Originally Posted by mbwhite View Post
Hey guys,

The last few rides i noticed the top RPM's reached isn't as high as it used to be. If i went WOT before the rpms would shoot up to 8400 and then settle out and hold 8200. The last rides it just shoots up to 8200 and then settles back to 7800 -8000 if i'm lucky. I thought it was the belt, so i put on my new spare. it's the same thing, the thing i noticed is that the dealer supplied spare belt is the 321115 belt and not the 321122 belt that came on the machine. From my understanding the 321115 belt is a cheaper belt, and when i adjust the proper belt deflection , it sits much lower in the secondary than my old 321122 belt.

Should my sled have come with the proper 311122 belt as a spare?? thats supposed to be there high performance belt. Any suggestions? Other than the belt nothing has changed except for the temp here warmed up from about -20 to about 0 degrees celcius. Would temp make that big of difference to the top rpms?
My 2011 SBa did the same thing after about 1500 miles. Was at different dealers multiple times and neither could really figure it out, swapped out the primary spring and it seemed to help a little but not for very long. Finally this year at the end of a trip it started missing and the engine light came on. It had an exhaust temp sensor code in it but it wound up being the engine harness. The dealer replaced both and its running like it used to with 4000 miles whack the throttle and it spikes to 8350 and then settles down to 8150. Good luck.
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