[GrizzlyXTR]

Got a 21 Grizzly Xtr 700 with coops machined sheave and Epi gold spring. What the biggest shim I can put in and how many mph will I lose ?

 

[Vincent]

Used to be 0.5 to 0.7 shim. You ll lose around 1.5 mph

Recently I saw someone on you tube who added 1 mm shim with a coop sheave without issue... that set up would probably lose close to 3 mph

 

[RedRocket]

Recently I saw someone on you tube who added 1 mm shim with a coop sheave without issue...

Do you recall if that person was running greaseless and had the primary moveable sheave grease cover removed?

 

[Vincent]

Do you recall if that person was running greaseless and had the primary moveable sheave grease cover removed?

The weights were greased so the cover was kept

 

[Windowlicker]

On my 19 Grizz I am running coop45 sheave, epi gold secondary , greaseless , no grease cover and 0.7mm shim.
With 27” Htr’s on 12” rims , mine tops out on the speedo ( hits limiter) at 58mph indicated , which is about 64mph using gps app on phone.
with just 0.5mm shim it was 59mph , neither here nor there really. I did go for a quick blast with no shims and it was 60-61mph , put the shims back for now , though I would like a greater top end as I do miss the top end sometimes.

 

[GrizzlyXTR]

Think ill notice a difference with a shim?

Question, With coops sheave, epi gold spring and a shim would you say I dropped 20-30% lower reduction?

 

[Blmpkn]

Spring makes no difference in cvt ratio, but yes, you'll notice a shim. I think shim&sheave end up reducing the ratio around 25%

 

[Vincent]

Out of the gate coop45 sheave rocks.

Shims aren't always needed, though they do help fine tune things further if required .

25 -30% lower initial cvt ratios vs stock is completely realistic with these set ups.

 

[firmani99]

How does that lower initial ratio translate to driveability? Just faster off the line? Any downsides to the upgrade?

 

[Blmpkn]

Faster off the line/easier to ride at low speed, SLIGHT loss of all out top speed.

 

[reogem]

How does that lower initial ratio translate to driveability? Just faster off the line? Any downsides to the upgrade?

With a machined primary only you will improve the low end performance and will not lose top end.
Any time any shim is added you will lose top end.

 

[reogem]

Spring makes no difference in cvt ratio, but yes, you'll notice a shim. I think shim&sheave end up reducing the ratio around 25%

True.. a spring will not change the mechanical ratio. The spring will keep the ratio in that sweet spot longer in low and midrange rpm's. The spring will increase backshifting. These two effects can really enhance open hot trail riding.

 

[Blmpkn]

Any time any shim is added you will lose top end.

This is true if the machine was capable of hitting the rev limiter before the shims were installed. Which, most 700s would id imagine.

My machine didn't have the mustard to get itself to the limiter before my shims went in, so my top speed has a good chance of staying the same. Ill be able to test this may 15th.

 

[Vincent]

This is true if the machine was capable of hitting the rev limiter before the shims were installed. Which, most 700s would id imagine.

My machine didn't have the mustard to get itself to the limiter before my shims went in, so my top speed has a good chance of staying the same. Ill be able to test this may 15th.

You still mite lose some top speed. Adding shims is like adding a larger rear sprocket on a dirt bike. Shims have a linear effect across the cvt shifting characteristics

 

[reogem]

This is true if the machine was capable of hitting the rev limiter before the shims were installed. Which, most 700s would id imagine.

My machine didn't have the mustard to get itself to the limiter before my shims went in, so my top speed has a good chance of staying the same. Ill be able to test this may 15th.

Hitting the rev limiter has no relation to shim VS top speed.
After you shim you may be able to hit the rev limiter but it will be at a lower speed and higher rpm.

 

[Blmpkn]

A machines ability to hit the limiter or not while stock, IS relevant when talking about shims & potential top speed loss.

If a machine can't hit its limiter, then obviously It's leaving rpm "on the table"

Shimming can help the machine reach that rpm left on the table by reducing the load on the motor at any given mph, allowing it to spin faster in a WOT scenario.

So, despite lowering the gearing.. being able to use that extra rpm is what could allow the machine to not experience a top speed loss.


It all depends on how close to hitting its limiter the machine was before the shims, and how far reduced the ratio was.

Obviously, if a machine was only 50rpm away from hitting the limiter... it would likely see a top speed loss from the popular 1.5mm and its 12% reduction.

If a machine was 500rpm away from the limiter though.. reducing 12% may be evened out by the ability to spin faster.

All this talk has me wishing my machine had a real tach.

 

[CanadianKodiak700]

If you add shims, you WILL lose top speed every time, regardless of hitting the rev limiter or not. A machined sheave done properly you will not lose top end but you will move your torque curve a bit lower giving that nice low end grunt off the line.

Sent from my Pixel 5 using Tapatalk

 

[Ridgway81432]

Most have never got to the rev limiter, the engine just runs out of poop due to the tame pulley ratio bogging the system down.
What I did was max out the pulley ratio which took shim and machining and 29mm weights, but I also ride a 660, and the maxed out was due to the belt crawling out of the secondary. 700's don't have the room in the cover for a truly high ratio.
Then to get max speed I cut the cam plate. The higher (not lower) pulley ratio get the bike going and the r.p.m.'s up then the cut cam plate squishes the belt harder before the to r.p.m. is reached. I can use 2 mm's of shim (the 660 is different than 700's) and add a 3 mm cut cam plate to counter act the shim after 20 m.p.h. and the extra 1 mm closes the primary sheaves further to move the belt to the outer reaches of the primary sheaves and deeper into the secondary.
I use a purple belt so those with something different need to rework my cam plate theory for their upshift rate.
To understand this ride with the cover removed to see the belt position at high r.p.m., to see if the belt is at full travel in the primary....and be careful to not get caught in the belt.

 

[Windowlicker]

Mine is definitely hitting the limiter , it’s a soft cut limiter , feels like a slow pulsing when it’s maxed out , visually verified by the afr reading going from mid 12’s straight to 16-17’s as its cutting fuel/timing ( assuming that is the method for limiting ).
I would like to look into the cam plate mod , I have the tools but not the schooling , may have to see if our friend google can educate me enough to tackle it. 🤔😬

 

[Vincent]

Mine is definitely hitting the limiter , it’s a soft cut limiter , feels like a slow pulsing when it’s maxed out , visually verified by the afr reading going from mid 12’s straight to 16-17’s as its cutting fuel/timing ( assuming that is the method for limiting ).

I believe I've experienced this with my 2019. I swear I've hit the Rev limiter, and like you mentioned, it's of a soft nature. It hard to detect because the wind and tire noises kinda drown it out @ 60+ mph

I've also recently considered the cam plate mod and reached out to Arnie Cooper for just this reason. In my case it would be over 250$ Canadian currency to get a modified cam plate of his to my home