Thanks for the info. So... it sounds like the 10-62's I have would be the equivalent to MTX 66's. With that said, changing down the 2 grams from the MTX 68's to 10-62's might give me an extra 200 RPM's which would have me at around 8100 to 8200 which would be right on. Does this logic make sense? Or I saw a set of 10-60's for $20. Would that be closer to what I should try?
I can't say on the 10-60's since I don't ride that elevation. Whatever 10 series worked/came close before, add 4 grams to that if you want to go the MTX route.
On the belt, the 3211080 (POLARIS 3211087 is a close tolerance version of the 1080) works on some depending on the heat, add venting, and for the cheaper price, why not try it is what I would say. With that softer belt, R.P.M.s may drop approx 200 compared to the 1115, or compensate with a 2 gram lighter weight.
From my
TECH TIPS THREAD under increasing your IQ pinned at the top:
ALMOST FREE MODS
PRIMARY CLUTCH
1) Check your primary sheave side clearance, should be .010" to .015" with a BRAND NEW BELT, mine & my bud's were .070" from the factory. Increases acceleration and reduces the slamming effect onto the crank.
2) Send your clutch out for balancing, (Preferably after the above step has been completed) noticeably smoother running and extends crank life. SLP ($35.00) and others here on SnoWest can perform this service.
3) Install a new primary clutch spring @ the start of EVERY season.
SECONDARY
1) Install only ONE DELRIN washer under the spring cup (less than $5.00)
2) Install a new spring @ the start of every season
BOTH PRIMARY & SECONDARY
1) Align your clutches (center to center 11.5" EXACTLY, and check for engine crooked, pictures posted in the "link" below as to how the the alignment tool SHOULD contact the front and rear of the secondary) Check this using the SLP or TEAM tool, as the Genuine Gold Plated POLARIS tool has approx .070" of built-in "kick" which is NOT what you want. Check your alignment tool bar for "straightness" with a 3' or so carpenter's level, drywall "T" square, etc., and vernier calipers. mountainhorse reported (2) defective SLP tools. Just because it's NEW doesn't mean it's PERFECT!
A)
WITH SLP PUSH LIMITER: 0 to .020" air gap @ the rear of the secondary, (with the front of the secondary touching the alignment bar)
B)
WITHOUT SLP push limiter: .020" to .040" of air gap @ the rear of the secondary (with the front of the secondary touching the alignment bar)
You may have to slot the engine bracket(s) to get it PERFECT. On mine and my bud's 07 D7 we had to slot the Mag side engine bracket almost 3/8" to straighten things out. A picture of the Mag side engine bracket is in the link below, do this step ONLY if necessary! Double check your c/c measurements after you get the engine "straight" and then slot BOTH engine brackets an EQUAL amount (if necceasry) to obtain the 11.5" center to center EXACTLY.
2) Check and adjust the offset after the above has been completed. This is E-Z to do, just adjust shims on the secondary shaft until the secondary touches the alignment bar. You want approx .030" of free play as well.
3) Lightly sand both the primary and secondary clutches with 180 grit sandpaper perpendicular to the way the belt rides and wipe down with lacquer thinner. Mark the primary with a fat black marker, make a few full throttle runs, and see where your belt rides up to on the clutch.
4) Wash/scrub (plastic bristle brush) your BRAND NEW belt w/soap & hot water, and let dry overnight, sounds weird but it removes the "mold release" compound that would otherwise would get smeared all over your nice clean clutches.
