Originally Posted by Grizzly7002014101
Not sure all’s I know is there 26 mud bugs
Most A.T.V. tires are not the size stated on the side wall, and as the grizz is a low compression, low output engine a small change in tire diameter can make big difference in how the grizz pulls at lower engine r.p.m.'s. If I remember correctly, your 700 came with stock tires stating 25" diameter that actually measured 23.5"s true. This was also the case with my 660 and with 700's until just 3 or 4 years ago when the dunflop tires came stock.
I'm telling this because the 660's and 700's wearing these tires were engineered for this tire diameter and when new, had a pulley ratio VERY near 2.5:1. This was a tame C.V.T. set-up for the average rider and over time most here on G.C. wanted more from their grizz and added mods for better performance.
The best, and for most, first upgrade was taller tires adding more ground clearance and better bite in the mud, snow or rocks, and with the taller tires came a larger tire diameter which caused extra drag to the grizzly drive system. What I learned after adding taller tires was in the stock C.V.T. drive configuration the grizz was damn near useless at this elevation. The first time I took it out with the new tires I was surprised that the performance was down so much so........I was lucky as a guy I ride with had a stock 660 the same year as mine so I could go back and make a few comparison measurements. I did not take these measurements before installing the new tires not knowing these would be important later.
The stock tires were actually 23.5"s tall, not 25"s as stated on the sidewall. Then the 26" new tires turned out to be 26.5"s tall true. I thought I was adding 1 inch when I actually added 3"s, which turned out to be an 11% increase in drag to the drive system of the grizzly. Then for my area, I can easily ride to 13,400 ft. making the stock engine produce only 48% of it power at sea level. This thing wouldn't go on the new tires where it had gone on the stock tires just 2 days earlier so I had a few changes to make.
For those reading this, then asking questions here on G.C., know it is important for you to let us know your elevation for best help. This helps us know what you have for performance before mods are added.
Here is an example you need to keep in mind about how taller tires kill the grizzly low end pull. If your tires are different than mine, you will need to adjust the number for your tires to learn what is going on with your bike. Years ago, just days after adding the taller tires, and while gathering info on what could be the problem, I was fortunate to have a couple members go riding with me for the day. I was with the guy on the stock 660 and another member on a 700 wearing 25" true tires. That day, on the same exact route I got to gather data on 3 different diameter tires and the findings turned out to be the key for me to understanding the grizzly C.V.T. system. All these machines had a 2.5:1 pulley ratio with the stock 660 on 23.5" actual tires, the 700 on 25" actual tires and my 660 on 26.5" actual tires. We had a G.P.S. receiver, actually two, for known true speeds so we ran the machines in formation and learned.....
The first thing is the stock tired grizzly reads speed higher than true. Mine on 26.5" true tires was dead on with the G.P.S. receiver, so when I indicated 20 m.p.h. I was going 20 m.p.h. The 700 odo had to indicate 23 m.p.h. at 20 m.p.h. true and the stock 660 odo had to indicate 26 m.p.h. at 20 m.p.h. true. This turned out to be a big deal for several reasons at the end of the day, as the stock 660 indicated many more miles traveled and burned a lot more gas than my 660 or the 700. Also, we did other formation riding comparisons at 40 and 60 m.p.h. true. At 40 true the 700 was showing 46 m.p.h. and the stock 660 was showing 52 m.p.h. and when I stepped it up to 60 m.p.h. true the 700 was barely able to stay with me and the stock 660 fell far behind. I have written of this years earlier, but those threads are now gone with new management.
I suggest you getting a few others together and make these type of runs for yourself. This data became important because at a give speed, we did this at 30 m.p.h. true, the grizzly engine turns so many times over a measured mile and this is where the tire roll-out becomes important, very important!
A 23.5" stock dunflop tire turns 856 revolutions over a measured mile. That is 856 turns of the rear axle, through the transmission through the pulleys and belt to the engine. I don't know the exact engine r.p.m. count for this but....it is a constant based on that tire diameter. Then, my new 26.5" tire turned 763 times over the same measured mile. And here is where things start to come together. The 23.5" tire has a roll-out/radius of 74"s and the 26.5" tire has a 83" roll-out/radius. This is an 11% difference, then if you take the number of axle rotations above, you see the difference there is also 11%. hum....I learned to raise the pulley ratio using machining and shims to increase the low engine r.p.m. pull by multiplying the torque produced and then discovered the fuel mileage dropped with the higher r.p.m. produced.
I then played with cutting the cam plate to change the up-shift rate. I use and enjoy the massive ratio out of the hole, then decided I wanted this additional torque to start going away at 20 m.p.h. for a transition to cruising speeds and greater fuel efficiency than stock. This is done by cutting the cam plate used to move the movable sheave against the belt. I also learned to use heavier weights, not lighter, for higher top speeds and lower cruising engine r.p.m.'s. Lighter weights let the engine scream for very low m.p.g. and that is not desirable in this area.
All mods listed in my signature are currently installed on my 660, and each makes a small change in a different aspect of the C.V.T. drive system.
There is no plug and play kit out there that does the same for every grizz, so for those needing help it is critical for you to let us know exactly what you have and what you want for the best help.