Motor Mounts causing low RPM in Axys Chassis

Murph · Apr 13, 2017

There have been many threads on RPM fade/ low rpm on the Axys chassis both here and on other sites/ forums.

I mentioned this cause/ effect in another thread but I wanted to start another in the hopes that it could help someone who was searching to find a solution sooner and easier.

One of my personal sleds, a 2016 Axys 163" 3" had an issue where it would only hit 7950 RPM.

Running 6-8000'. 163" x 3" Normally aspirated, stock pipe and can, went back to stock helix and magnum force weights to eliminate variables. Put a rebuilt P-85 in it. I could add or subtract 3.6grams per arm and peak rpm would remain the same. The "pull" down low was significantly stronger with more weight but the motor only pulled 7950. Reduced weight and no improvement.

My motor mounts -specifically the rubber isolators- were sacked out. The torque arm rubber isolator was also hammered. I believe the motor was shifting back enough to significantly reduce center to center distance.

Replaced all five rubber isolators.

Had to readjust clutch offset after replacing isolators. Motor now pulling 8250-8300 rpm.

I will start replacing all five rubber components at 1,000 mile intervals (typically two sets a season) from now on.

richracer1 · Apr 13, 2017

I will add, one way to help eliminate this is to install some torque arms, like the Fire & Ice versions. Just a thought. I have their Mag & PTO arms on mine.

I'll add that I'll be replacing mine this summer after two seasons, not that expensive and easier to do.

RMK-King · Apr 13, 2017

I was visiting with a turbo dealer earlier this winter, he said with a turbo these engines were moving a inch on the dyno under boost, 1/4-1/2" N/A at full throttle. These motor mounts do seem to flex more then necessary.

Jreng87 · Apr 13, 2017

So are you just replacing the inserts?

And how are you determining if they are worn or not?

Midwest Summit · Apr 13, 2017

richracer1 said:
I will add, one way to help eliminate this is to install some torque arms, like the Fire & Ice versions. Just a thought. I have their Mag & PTO arms on mine.

I'll add that I'll be replacing mine this summer after two seasons, not that expensive and easier to do.

Do you have the same wear in the rubber mounts with the torque arms?

richracer1 · Apr 14, 2017

Midwest Summit said:
Do you have the same wear in the rubber mounts with the torque arms?

Haven't looked at them yet.

adamg · Apr 15, 2017

Can you list the part numbers you are replacing? I want to be sure I get all of the parts needed to do the job.

My 16 Axys 163x3 has similar behavior. Max 8150 RPM when new, now with 1300 miles it's generally in the 7900-8050 RPM range, and this is after dropping 2grams of clutch weight (down to 10-62) and going to blue-pink primary spring at 7000'. Rest of drivetrain is stock.

I've tried a lot of things to get RPMs up to where they should be. The only things left on my list:
1. new motor mounts
2. new exhaust valve actuator and cable (maybe try disconnecting the cable and zip-tying the valves wide open first?)
3. new pistons and rings
4. sell the sled and get a different one

List of some of the things I've done, all with ZERO change to WOT RPM:
1. new belt
2. old style 1115 belt
3. clean exhaust valves
4. re-learn exhaust valves
5. change from 10-64 to 10-62 weights
6. change from factory to blue-pink primary spring
7. new plugs
8. four TPS adjustments all by varying people and techniques/tools
9. compression test (both cylinders are 125psi cold at 1800'ASL)

Murph · Apr 15, 2017

adamg said:
Can you list the part numbers you are replacing? I want to be sure I get all of the parts needed to do the job.

My 16 Axys 163x3 has similar behavior. Max 8150 RPM when new, now with 1300 miles it's generally in the 7900-8050 RPM range, and this is after dropping 2grams of clutch weight (down to 10-62) and going to blue-pink primary spring at 7000'. Rest of drivetrain is stock.

I've tried a lot of things to get RPMs up to where they should be. The only things left on my list:
1. new motor mounts
2. new exhaust valve actuator and cable (maybe try disconnecting the cable and zip-tying the valves wide open first?)
3. new pistons and rings
4. sell the sled and get a different one

List of some of the things I've done, all with ZERO change to WOT RPM:
1. new belt
2. old style 1115 belt
3. clean exhaust valves
4. re-learn exhaust valves
5. change from 10-64 to 10-62 weights
6. change from factory to blue-pink primary spring
7. new plugs
8. four TPS adjustments all by varying people and techniques/tools
9. compression test (both cylinders are 125psi cold at 1800'ASL)

qty1 LIMITER, TORQUE, ENGINE
Polaris
item: 3022281 $26.23

qty 2 MOUNT, ENGINE INSERT RAD, PTO
Polaris
item: 3022697 $14.51ea

qty 2 MOUNT, ENGINE INSERT RAD, MAG
Polaris
item: 3022698 $14.51ea

After installing, recheck clutch alignment/ offset

TheBreeze · Apr 16, 2017

Reminds me of my cat m series days! Here I though I was done filling trash cans with motor mounts.... lol

Davajn · Apr 16, 2017

Why not have a shop make a couple of delrin mounts to test instead of oem?
What kind of problems would occur with harder mounts?
And is the upsides worth the tradeoff of the downsides?

Murph · Apr 16, 2017

Davajn said:
Why not have a shop make a couple of delrin mounts to test instead of oem?
What kind of problems would occur with harder mounts?
And is the upsides worth the tradeoff of the downsides?

We have been discussing this internally. Delrin or any other more solid mount may create other problems.... Just like the lightweight crank has accelerated clutch component wear.

I am curious how bad it would shake. These motors move A LOT. Seem to move in every plane.

But, I would like to see the motor/ clutch alignment stay more constant throughout the torque delivery. This motor moves visibly rearward as power is applied.

AdrenalineAddict · Apr 16, 2017

I had similar results to Murph after I changed motor mounts, belt, changed my secondary spring and went a couple grams lighter for springtime temp tuning. I am thrilled that I am seeing 8050 RPM again at 9,000 to 10,000'. The belts I was running weren't worn out in my opinion, they measured 1.410" instead of the new width dimension of 1.435". After a 1.5 month ordeal of having dealers inspect the sled, field question after question and be of no help whatsoever I finally discovered that guys like Murph hit the nail on the head and made some great discoveries. Now if the dealers would get a hold of this relatively simple advice, and advise and service as they should there wouldn't be nearly as many annoyed Polaris customers out there.

Sage Crusher · Apr 16, 2017

AdrenalineAddict said:
I had similar results to Murph after I changed motor mounts, belt, changed my secondary spring and went a couple grams lighter for springtime temp tuning. I am thrilled that I am seeing 8050 RPM again at 9,000 to 10,000'.

Don't be to trilled @ 8050 @ 10,000' and up as we spin em @ 8350-8400..
As was stated in my previous post in the tubo thread, yep these motors do move as Murph stated- and the added boost of the turbo enhances the issue.
Motor mounts are now a on-the shelf- item, but it's the price we pay in the boost section- on a non-boosted sled.. just keeping an eye on them is becoming more than annual ritual.

Davajn · Apr 17, 2017

Murph said:
We have been discussing this internally. Delrin or any other more solid mount may create other problems.... Just like the lightweight crank has accelerated clutch component wear.

I am curious how bad it would shake. These motors move A LOT. Seem to move in every plane.

But, I would like to see the motor/ clutch alignment stay more constant throughout the torque delivery. This motor moves visibly rearward as power is applied.

I see that it could create problems. But i think by just adding torque arms like fire n ice would solve most problems to be honest. It doesnt allow the engine to create a rearward motion at the PTO side.
But they are abit expensive!

TRS · Apr 17, 2017

Davajn said:
I see that it could create problems. But i think by just adding torque arms like fire n ice would solve most problems to be honest. It doesnt allow the engine to create a rearward motion at the PTO side.
But they are abit expensive!

The torque arm is a great idea. The only problem accompanying the torque arm is finding a way to alleviate the monstrous amount of lead in PII has built in to the AXYS.
The center to center distance must change, in its stock form, to get the lead in and offset into a neutral position. The torque arm eliminates this movement. The premature wear on the stock mounting systems components along with belt life quantifies this known fact. Drive components must pull or wear themselves into alignment getting to that happy neutral position. Think about that for a moment, how many components on your other toys have worn out or failed because of misalignment? Trying to get to that ultimate neutral position. Shock bushings, chains and sprockets, tires, and so on.
PII needs to work on their engine mounting system to get these parameters under control that will insure component longevity, belt life and a consistent RPM

goforbroke · Apr 17, 2017

Want to try replacing mine. How big of a deal is it to do? Any instructions?

Thanks

Murph · Apr 17, 2017

goforbroke said:
Want to try replacing mine. How big of a deal is it to do? Any instructions?

Thanks

Not a big deal. Just have to remove muffler and primary clutch.

Torque arm mounting screws to case are a tight space but still pretty easy.

MDEVO · Apr 18, 2017

Jreng87 said:
So are you just replacing the inserts?

And how are you determining if they are worn or not?

As you can see in his pictures, just the inserts for the 4 motor mounts, and the torque limiter assembly, as listed a few posts above...

I noticed my sled was visibly vibrating more on the last couple rides, so I had a look and saw the rear PTO rubber isolator rotating. The motor did not vibrate too bad when it was new. It has 650miles.

I'm changing all in the off season......

mountainhorse · Apr 18, 2017

Great thread....Thanks Murph !!!

.

LoudHandle · Apr 19, 2017

MDEVO said:
As you can see in his pictures, just the inserts for the 4 motor mounts, and the torque limiter assembly, as listed a few posts above...

I noticed my sled was visibly vibrating more on the last couple rides, so I had a look and saw the rear PTO rubber isolator rotating. The motor did not vibrate too bad when it was new. It has 650miles.

I'm changing all in the off season......

If they are rotating; your bolts are loose as well.

Motor Mounts causing low RPM in Axys Chassis

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