I got to reading the different member's experiences for C.V.T. mods to counteract taller tires and decided to add a few words abut what is going on, and to suggest thinking of the changes/mods in percentages.
WHAT, you may ask?
I joined G.C. because taller tires massed with my set-up and I did not have it figured out on my own. Searches on this led me to G.C. and to ask a question a membership was needed, sound familiar? :)
The deal is, very few tires have the actual diameter stated on the sidewall so like with me, going from the stock '06' dunflops marked 25"s tall, that were actually 23.5"s tall started the problem. It was a couple years of testing later i realized why, and this is that part of the story....
Due to gearing in the transmission, it takes so many engine rotations at a chosen speed to get the grizz down a measured mile. The variable pulley system causes this number to change for a given speed, so when trying to deal with a specific aspect of the drive system pick a speed to focus on. I picked zero speed, 20 m.p.h. and 40 m.p.h. as my focal speeds.
The example what my set-up offered, the 23.5" tires have a 74" roll-out, so for the mile the math is:
5280' x 12"s divided by 74"s for the number of times the axle turns over a measured mile.
Then the tires I added had a 83" roll-out so the math changed to:
5280 x 12"s divided by 83"s for less turns of the axle, thus few engine revolutions (engine power produced).
My percentage change of axle rotations per mile was about 11%, so I learned that raising the pulley ratio this same percentage amount was the trick to get back the stock feel.
Members in above posts has said they added a 1 mm shim and were not impressed, but satisfied, well now you know why I have for years been suggesting you count the starting and ending pulley ratios. 1 mm of shim, depending on your bike, may be good for 4 to 5 percent change, you did not add enough. Oh....then as for the 1.5 mm recommendation, that is because 1.7 mm's is all most newer 700's will accept before the grease cover screws start rubbing the primary cage. More will go in, lime up to 2 mm's, but then other changes need to be made. (My older 660 has a lot of room under the cover, and will take 2.5 mm of shim, with the limiting factor being the shaft spline that engages the cam plate. Each model has a limiting factor and not all limits are the same.)
In a nut shell, I picked 0 ground speed (at launch) because of the number of C.V.T. mods I run in combination. All listed in my signature are currently installed in combination.
I have a high ratio for launch, the high ratio magnifies torque produced. The stock engine produces whatever stock torque which the wet clutch is designed to handle at the stock engagement r.p.m., so I have experienced no wet clutch problems. Then once the torque power is transferred through the wet clutch, I use pulley ratio changes to multiply the torque for more haul-ass. I can get a 3.75 ratio and use a stiffer spring, but then the axles start to break, so I stay with a 3.54 ratio maximum and the purple spring works for that at this elevation. I say this elevation because my grizz lives at 7000 ft. and is always down 28% on power from sea level. You guys at sea level will have more power, so you may not need what I have found. My signature is to let you know what can be done with a little thought and effort.
My basic numbers went like this:
I started with a 2.5 to 1 ratio, so increasing 11% made the ratio 2.775 to 1. That could not be reached with 1 mm or shim.
This may help some of you understand why the 3 to 1 ratio feels good, it takes care of tires in the 26" to 27" diameter range depending on your actual tire diameter.
Now you may understand when running my 3.54 ratio, almost 42% better than the stock 2.5 ratio, this thing is very responsive.
I picked 20 m.p.h. as a focus point because that is as fast as i want to hit the big rock in this area, so that is the speed I want the grizz to transition from a rock bouncer to a cruiser. I did this by different weights for the spring used and the starting ratio. If I install a different ratio the transition speed to cruise is lowered. The 20 m.p.h. speed dictates the length of cut for the cam plate mod#2, and the 40 m.p.h. speed determines the amount of bend before welding for high gas mileage.
The video was done with me following 3 other members on 700's, we let the first two take off, then caught them in 3 or so minutes. At the 3:40 mark you can see the guy ahead of me start rocking because his 700 running about a 2.9 ratio was done accelerating, and my 660 had a lot more to give. I could have passed him and he knew it, oh and this was the member here that just the day before we did 455 miles in one day. I was using a lower ratio then the 3.54 because on the long day ride needed high mileage. That was because we needed to carry all gas needed for the day, for two machine over that distance. Then we meet the other two members the next day and this was the beginning of that day which covered 134 miles, or so. As for the high mileage aspect, the day this video was done, I was a mile or two from the truck before needing to use the reserve part of the tank. That was about 4 gallons for the day.
There is no one size fits all for those wanting plug and play C.V.T. mods, but if you are like me and willing to put in time and experiment some, the grizz can be made much more user friendly platform. It is already reliable, it just needs a little more fun :)