Ski-Doo Snowmobiles Forum banner

The Downfall of the 1000 SDI ???

92464 Views 384 Replies 35 Participants Last post by  Daag44
When I first joined DooTalk there were a number of owners who took a special interest with the 1K and we tried our best to understand this beast. We were all fighting to figure out the reasons why these behemoths were failing and how to avoid the aftermath. At times we created such a ruckus that it eventually drew us apart even further. It got to the point that it turned into a choice between BRP designed the engine to fail, or they were not running right. To me this was the demise of the 1000 SDI on the DooTalk forum.
  • Like
Reactions: 4
361 - 380 of 385 Posts
BRP has classified the 1000 SDI as Vintage!

I do not know when this happened, but BRP has sold all of their left over parts for the 1000 SDI. We can no longer buy parts for this sled through BRP, although we still can buy from the supplier through the BRP dealers.

I am reminded of a forged piston discussion we had on this sub-forum when That Girl Racing was warning us that one day soon we would no longer be able to source OE pistons and that we better figure out how to make them work. It will also be about salvaging parts and an even greater focus on ensuring they keep running well without needlessly replacing parts.

A normal riding 800RE with OE parts will last an easy 10,000 km, and to 16,000 km with diagnosing problems early, and more if you are lucky or make your own luck. The 1000 SDI in my opinion is good for at least 25,000 km ridden the same way and taking the necessary steps. The only reason that I believe this is because it has been done by others who managed to make them work.
See less See more
  • Sad
Reactions: 1
Reliability Upgrades

RX7MachZ and I spend about a few years trying find the best way we could think of to lower the number of upgrades/mods and gauges to a bare minimum. This is what we found.

1. Voltage Gauge.
2. 2007 wiring for the larger ECM Ground Collector.
3. Proper bolt torque on the cylinder and head bolts.
4. Tack both sides of the base gasket during installation.
5. LP pump Airtex 8012S and a relocate from under the engine.


1. The voltage gauge is the gauge to show electrical issues.

2. BRP increased the size of the ground wire that collects all the Black/Blue ground wires that server the Engine Management. The ECM itself has five ground wires and there is one for the eRAVE servo and another for the gauges.

3. Bolt torque should not be mod, but the errors in the shop manuals makes this an upgrade. If you want to keep it simple and easy to remember, just use 40 ft-lbs for both cylinder and head bolts. Be careful with replated cylinder monoblock that have worn threads from over-cleaning which is a real thing. If that is the case then use a lower torque and make sure to check the torque again after some use.

4. Tacking both sides of the base gasket is to keep them from leaking which does happen for whatever reason like over-cleaning. Keep in mind we are not playing with new engines out of the Rotax assembly line, but rather old monoblocks that have been replated who knows how many times. Threebond 1211 is probably the easier sealant to use to mate the crankcase halves and we use the same to tack both sides of the base gasket. It is not same quality as the Loctite 5910 that BRP uses, but when you have the engine together and realize that it needs to come apart again for whatever reason, you will understand the benefit, and it is a known sealant, and it works.

5. The Airtex 8012S. Why? Thanks to RX7MachZ who installed in his sled back in 2011, so far it has been the one pump that has survived fuel and electrical issues. I cannot provide assurance that it is the best pump. All that I know is that it has not shown any problems, and there is nothing on the forum to show otherwise. The infamous Carter Caroter on the other hand, has shown issues when installed below the level of the gas tank. For whatever it is worth, we had the fifth and most recent documented failure on DooTalk with the carter caroter vane pump. Carter makes other types of pump, so this is nothing against Carter. Heck I called their technical support line and they confirmed that installing a fuel pump below the gas tank is a bad idea. Since below tank has become the most common relocate, then there should be a better chance with the Airtex, and if above thank then I guess most pumps will do just fine.

* Why is the Fuel Pressure Gauge not in this list? Keep in the mind the objective was to find the least number of mods/upgrades. Heck we also needed to remove our Widebands from the list which we both found difficult.

* Why no other ground mods? There are several reasons. The fist one is to keep the number of upgrades/mods as simple as possible. The second is that when the grounds were cleaned, protected against corrosion, and well secured with with the required serrated washers same as the OEM setup, we found no issues. RX7MachZ and I have slightly different takes on this, so it is worth mentioning. RX7MachZ prefers to add ground to avoid poor contacts with the chassis, while I prefer relying on the chassis to lower the amount of noise and ground loops. We have seen both methods work, so pick whatever solution best fits your own experience.

** Keep in mind that this a list of mods/upgrades that we came up with. It was never meant to show what you should do.

Reliability Maintenance

* In order of importance *

1. Clean the injectors a short time prior to the first ride.
2. Clean each of the four Chassis Grounds.
3. Adjust the oil cable for adequate oiling.
4. Follow the in crankcase crankshaft runout.


1. The type of cleaning we do is very basic.

Some owners have never cleaned their injectors and never had problems. So this is something that you need to figure out on your own. I have done the work to prove beyond a shadow of a doubt that of all the 600 and 1000 SDIs that have failed at the beginning of the season - usually the first long ride and not riding around in the yard - the main cause was the injectors, if not always the cause.

Again, I have seen, test rode and witnessed those sleds that appeared to be problem free at the beginning of the season. So if you are among those then I assure you that I know about those sled. The problem that I am covering are those that don't which I have also witnessed and there are far too many. Partially clogged injectors are the single most leading cause of lean/detonation failures on the 1000 SDI.

There is a gentlemen at a Diesel shop in Candiac, Quebec who was cleaning SDI injectors for various BRP dealers around Montreal at the time when the 1000 SDIs were dropping like flies that can substantiate my findings. The worst recorded clogged injectors on the 1000 SDI were cleaned in March and by December they were 100% blocked. They normally flow in the 90s% range and the tolerance is around 6% for the Sea Level map.

And please note, that even if you have cleaned the injectors as we have, I have no way to insure they are flowing properly. The only assurance you can get is from running a Wideband to confirm the average air/fuel ratio between the two cylinders is correct, and EGTs to conform the air/fuel to both cylinders are relatively even, and a plug read confirm the gauge readings. In other words this post is not meant to cover every possible problem with the injectors.

However you play the 1000 SDI, please do me a favor and make sure the injectors are working as they should. You can do every mod in the book, but if you get this wrong then none of those will count to protect the engine from a imminent failure.

And note that the high speed injectors kick-in at 6,500 rpm which can be verified with a simple DMM meter across the high speed injector fuse. Every problem you have read that stemmed from being run above 6,500 rpm due to the exhaust valves (eRAVE) remaining closed, were for the most part due to the lack of flow of the High Speed injectors! The only known exception were some of the MY2006 with the wiring for the high and low speed injectors reversed.

2. There are four Chassis Grounds, one for the battery, one for VR, one for the Engine and one for the ECM (Engine Management). I listed them all in order with the one for the Battery being the worst. They need to be cleaned and protected against corrosion, and then secured properly with the serrated washers supplied by BRP. For the reason of being secured to an aluminum chassis, it is of the upmost importance to place the serrated washer between the surface of the chassis and the terminal connector. And please do not bother sourcing these serrated washers elsewhere than BRP. Even if you try you won't find the same quality and fit and material needed for this purpose. Clean the surface well, apply dielectric grease, and secure the terminals. There are four of these Chassis Grounds, so this is a big deal. Do it once, do it right, and be done.

There is a fifth ground for the Lights & Accessories. It is isolated from the Chassis ground which serves it purpose. One advantage that I have found is to prevent a surge during hi/lo beam switching to affect the loads in the ECM and Engine Management including the gauges. If ever the OEM VR becomes difficult to find, I would use a generic VR and splice the power and ground to feed the Lights & Accessories in the same fashion.

3. I have already written about the oil consumption ad nauseam, but there is always something worth repeating. Graduate the oil tank to more easily follow the oil consumption in relation to fuel consumption.

4. This is probably the most difficult part for any of us. If the crankshaft runout reaches too far, what are we expected to do??? With too high of a runout the only to do is limit the amount of wot. Otherwise I assume the only other possibility is to have the crankpins welded straight. I do not know what shops can do this, but I do know that D Garland & Son in Ontario, Canada is the best resource we have. They probably don't remember my handlename, but if you tell them that a Mach Z guy on DooTalk that referred you to them, then it might ring a bell. If not, then add the guy who called them a few years ago with insights learned from DooTalk on straightening the QRS secondary. It doesn't really matter, just know these guys are into industrial balancing who happen to have decades of experience with balancing crankshafts for snowmobiles with a specialty on Ski-Doo.
See less See more
  • Like
Reactions: 2
Wow….. awesome post Daag. There is just so much great information here. Although I’m sure we all knew that it was going to happen sooner than later. It is sad to read that our beloved Mach’s have been delegated to vintage status 😢
  • Like
Reactions: 1
Top Tier Gasoline Worth the Extra Price, Study Shows

An analysis by AAA reveals that gas with detergent additives can keep an engine running smoothly
By Jeff S. Bartlett
Published July 7, 2016 | Updated March 2, 2022

I picked up the link from the latest Total Seal video and added it to my Gasoline quality and storage topic. I had not added anything sine 2015, but over the years I have updated the links that quite working, although I haven't checked those in a long time.

I buy 98% of my gasoline at Esso which was once listed as a Top Tier, but it still uses a superior additive package. This could certainly contribute to keeping the injectors happier and explain in part why some have had better luck. Our 91 is Ethanol free, so that's a big plus for storage which is the main part of the problem with the injectors. In following fuel issues locally, regionally and across DooTalk, fresh 91 is a safer bet than 93/94, at least during periods of low turnover such as the fall and beginning of winter. Even if 93/94 was cheaper, I would still pick 91 for the volume of sales.

Petro Canada, Esso, Canadian Tire, Husky and others are no longer designated as Top Tier Fuel
Apr 4th, 2022
See less See more
  • Like
Reactions: 1
I like Shell VPower premium for my high performance cars for similar reasons. It has less ethanol and just runs better in a high compression engine.

Daag, is your 91 still ethanol free? I have been reading about the changes in fuel regulations that were imposed in Canada in late 2022, and it looks like ethanol in all gasoline is a first step to meet those regulations.
  • Like
Reactions: 1
So far our local 91 from Esso and Shell remains Ethanol free. The nearest 94 is from Petro Canada which does have Ethanol and is the one we have proven at the time that it caused knock on the same high performance car that had no issues with 91. The same car with gas across the border experienced knock driving on the 87 in the mountains along the Adirondack, the Schroon Lake region if I am not mistaken.

I have often wondered if a small 4S engine could be setup to knock on 87.

"According to Dan McTeague, a noted petroleum analyst, Shell and Esso 91 are both ethanol free."

Why you don't actually want ethanol in your gas tank
If you're looking to store your classic car, motorcycle, or ATV for the winter, here are a few precautions

Author of the article:
David Booth
Published Oct 11, 2019 • Last updated Jun 10, 2022
See less See more
OK, good, I hope it stays that way. I only buy ethanol free fuel for my older vehicles and small engines.

As I understand it today, the new Canadian gasoline and diesel regulations require the fuel manufacturers to reduce their 'carbon intensity' by something like 3% now and another 1.5% per year for some years. The first easy step to reduce 'carbon intensity' in gasoline is to add more ethanol, as ethanol apparently produces a given amount of energy with less carbon emissions. Making their factory process use less energy can do the same thing.

The fuel manufacturers can buy carbon credits from other companies like EV manufacturers. So the price of gasoline will go up when that tactic to reduce 'carbon intensity' is used, and the EV industry will be subsidized by gasoline buyers.

BTW it is interesting that the 94 with ethanol produced knock. Ethanol is one thing used to increase octane; it burns with less total energy and so the combustion temperatures and pressures are lower. But the other fuel ingredients, or a slower ethanol burn rate in a larger bore cylinder, probably caused the increased knock. (What engine was this?) The fuel article that I shared with you talked about the major gasoline blending components.

You can make any engine knock on any sold octane. Just advance the timing....
See less See more
BTW it is interesting that the 94 with ethanol produced knock. Ethanol is one thing used to increase octane; it burns with less total energy and so the combustion temperatures and pressures are lower.
I can only speculate what was in that tank since there was no testing to confirm the content and RVP. For all I know the last fill-up of the 94 UST (Underground Storage Tank) may have been 87. I don't expect Octane cheating at Petro-Canada, so I thinking the same kind of mistake that leads to filling-up a gasoline UST with diesel. The same happened to an off-trail 850 that had filled-up in South Dakota and detonating enough to loosen the spark-plug at mid-day, and the next day it broke. Due to the E-TEC plugs that need to be indexed, it was reasonably assumed the plug had not been tight enough, and after being tightened back up it maybe it had already been weaken from bouncing around, or whatever, it doesn't really matter since the was a problem to begin with. The same sled self destructed on its first back to Minnesota closer to sea lever when it has more compression. The take-away is that even an E-TEC is not fully protected against gasoline issues.
See less See more
eRAVE operation

I finally found the old topic for the eRAVE malfunction from Jan 29, 2015. I added the link to Post #192 which is now over 5 years ago. The essentials is the Engine Pilot Light is triggered on Wide Open Throttle after passing 6,500 rpm, or from a cruise at ~7,200+ , then the exhaust valves are not opening correctly or fully, and it is time to back off the throttle and ride below exhaust valve opening until the problem is resolved. In other words, recognize the problem early and avoid the attempt to power/throttle through the problem area.

Below are topics for the historical purpose. There are many more, but those can provide good clues. Since I have not seen any problematic RTs in many years, I suspect they have either been junked or parted out. I added the third link to show how this problem is still happening in 2023 with the 850s. In Post #85 I included a link to show it is also still happening in 2023 with the 600 HOE. So if you encounter someone who is adamant that the RT was singled out, at least you will have a reference to the "bullet proof" 600s that also have the same problems that will lead to similar engine failures. It is not a good practice to drown another sled to raise one's own, but knowing that the "bullet proof" 600s are also falling can serve its purpose to regain confidence in 1000 SDI not being an isolated case.

pto side piston lean out on exhaust side

ERAVE activation light for an RT

My history with the servo operated exhaust valves
See less See more

Old comments on the horsepower of these produced, apparently stock?
  • Like
Reactions: 1

Old comments on the horsepower of these produced, apparently stock?
That was a good find. Part of what was missing in those dyno sessions was a Wideband reading from the center pipe.
2024 Ski Doo MXZ XRS 850 E-TEC Turbo R

Have you seen the latest turbo 850R?

It has a minimum of 165 Hp, and 180 Hp at full boost for the elevation and air temp.

With both the turbo 900R and 850R, the goal appears to be 180 Hp.

I think the old NA 1000 SDI is still holding its own.

See less See more
Good reading. All I know is my black and red 1000 cc Mach 1 was my favorite sled I have ever owned. Even if they could replicate it, all the other sleds have such good performance it probably wouldn’t be as special as that sled was at the time.
  • Like
Reactions: 2
Good reading. All I know is my black and red 1000 cc Mach 1 was my favorite sled I have ever owned. Even if they could replicate it, all the other sleds have such good performance it probably wouldn’t be as special as that sled was at the time.
Are you still around? Sorry that I left your post without a reply. I hope you take the time to elaborate on what you liked about it. Much like the 1200 4-TEC shorty, the 1000 SDI holds the trails like on rails. I think it took 17 years for BRP to show the claim to fame of the Mach Z was its low suspension and low center of gravity on trails. They sorta sold it twice as a lake racer, when really it was a phenomenal trail sled. The tricky part is having to figure the suspension. My Renegade was never good, so I had to ride multiple Mach Z to understand the wow'ness I was reading about. The typical 121x15x1" track with 96 studs was an ideal setup for enough traction on trails that also provided give to drift the rear end while the lower center of gravity kept it planted. I learned from riding RX7MachZ' sleds hat it was a hit and miss. One year his sled was on rails, and the next year I found it awful with rebuilt shocks. Then he picked-up a 2007 Mach Z that already had the suspension work, and it rode better than any of his previous Mach Z!!!! It would be fun to copy a setup, but I do not know how.

In my opinion, there is more than enough for the engine to get in run reliably. I keep going for whatever reason, but in my opinion there is need to focus on the front/rear suspension and ride height.
See less See more
Clutch Alignment

This is the G4 clutch alignment tool designed and sold by Tim @ Grip-n-Rip that RX7MachZ and I tweak to fit the Gen1 REV/RT to Gen 3 chassis. Thanks to Tim's effort, there is more known in recent years about clutch alignment then ever in the past. In my opinion it was the greatest advancement to clutch alignment ever as it provides the alignment in three different axis. We did not do the necessary camera and belt temp monitoring work needed to fully adapt it to the previous chassis, but the concept remains effective. For example, we are able to simulate the movement of the clutch under load to measure the difference in Y-X measurement.

Ideally, the Y-X measurement should be zero for the greatest part of riding. If the sled is used in competition, then the focus should be on the alignment at wot. For a trail sled, most wot lake runs are under 30 seconds and there is so much ventilation at those speeds that it should help keep things cool. For trail riding the goal is to find a happy medium.

Wheel Motor vehicle Automotive tire Automotive design Automotive lighting

Added Clutch Alignment

See post #239 of the following linked topic below.

For any clutch alignment that is needed above what is provided in stock form, there is no limitation. This is what Icanfixit showed with his 800R E-TEC to eliminate that limitation in showing the added adjustment in two axis. For the third axis that is not shown, the alignment is done with the use of shims in the engine mounts. I have seen a shims on a 2009 800R P-TEK that was an OEM build. I don't remember if it had a hole or a PAC-MAN slot to fit by the mounting stud like the shims that Grip-n-Rip made for the G4, but it most certainly had a tab to hold and ease manipulation which has me think it was OEM. In 11 years I would expect to have come across at least one reference on DooTalk, but not yet. Dumb me for not having taken a picture of it. Anyways it does not really matter as we can make our own shims when needed.

Note the post #239 was on June 30th of 2016. This was only a short period in months before the first 850s were delivered, and back then we had no clue what was about to transpire with the greatest clutching alignment problem in snowmobile history. In many ways the 2017 850 overshadowed the Mach Z RT. Even back then I had no clue of the versatility of our Gen1 to Gen2 sleds, hence the forefront that Icanfixit presented to us in 2016.

What I am trying to say is, the 2016 to 2017 year was an eye opener. What Icanfixit posted in Summer of 2016 was something that most of us, or at least myself, did not even realize was well within our means/reach. And the technology that BRP brought forward for MY 2017 is what pushed the clutching alignment to a whole other level that had never been seen in the past. 2016 to 2019 were the three years that would define the leaps forward.

See less See more
  • Like
Reactions: 1
Axes or Dimensions?

X is the position of the Primary/Drive clutch in relation to the Secondary/Driven clutch. This is a measurement taken where the two clutches are nearest to each other.

Y is also the position of the Primary/Drive clutch in relation to the Secondary/Driven clutch, but it is a measurement taken where Primary is furthest away from the Secondary. Hence Y is on the same axis as X, and the Y-X offset is second dimension of to clutch alignment on the same axis.

Z is the distance between the two clutches, hence a second axis and third dimension.

X-Y-Z is typically used to show the three axes, yet BRP has made use of those for three dimensions/measurements on two axis.

Does it really matter?

It depends on what we are looking for. In my previous post I referred to a Third Axis, yet the X-Y-Z measurements shown in the Shop Manuals suggests that all three axis are being covered, yet they are not. Since Y is a measure on the same axis as X, the Y could be converted to X2, hence X2 - X1 = X offset.

The Z is already taken for depth, therefore it leaves Y as the missing axis to measure the height of both ends of a shafts (crankshaft and countershaft) to determine the angles. Therefore Y2 - Y1 = Y offset.

Engine torque/pull under load

The load of the engine will pull/torque it in on the engine mounts for the X offset, and pull/torque it up for the Y offset. Keep in mind the two clutches are not horizontal. Since the secondary is placed higher to make room to move our feet further forward (hence rider forward) the engine on the mounts is being pulled/torqued inwards and upwards.

The placement/height of the secondary in relation to the primary was not yet all that much on Gen1 REV/RT, but it grew for the Gen2/Gen3, and again for the G4/G5. So while the Y offset does not matter as much for the Gen 1 REV/RT, the principal/understanding of this Y axis allows to see the importance of shimming the engine and secondary.

Where it gets interesting is how this affects the contortion of the belt. The first picture shows how the belt can be forced to bend/contort in a strange way on the X axis. The example I drew was having an X offset and comparing what it would look like for the belt with only shimming the secondary. There are two dimensions showing on the same X axis. The X2-X1 offset is the same, but the X is different. It is meant to show that even with a bad offset, that shimming the secondary alone can have a large impact on the belt alignment. I based the example off of the first years of the Gen2 REV/XP chassis which had trouble with the clutch/belt alignment.

Now take the first half as an example, and imagine you are only measuring/correcting the X offset. Can you see how it could potentially make things worse by contorting the belt even further into a more significant S shape?

Have a look at this second picture that shows the Y axis that I believe is missing. The previous picture showed the belt contorting in two dimensions of the same X axis, the X and X offset. The Y axis is adding two additional dimensions to contort the belt further for the Y and Y offset. Note when asking for help to buy a used sled there is solid advise to check the front shocks in relation to the A arms, and any visible bend or crack showing in the S module (front module for the Suspension Module), or in the E-Module (Engine module) that would show an accident. This is perfectly sound advice that I use and fully support. But what happens if we remain the owner after an impact, is the clutch alignment brought up? Usually yes, but only on the X axis and maybe for Z axis, but nothing for the Y axis. Hence the Y axis is completely ignored on all sleds like it did not exist. I assume it is being ignored for the most part due to clutch alignment specs are showing X-Y-Z.

By the way, we are today 5 years after being taught the advanced alignment. The explanations and depictions are my own, but the understanding was given to me 5 years ago. To give perspective, I began this topic nearly 6 years ago in July.

See less See more
  • Like
Reactions: 1
Runout (800R E-TEC example)

The runout measurements of high mileage large bore 2S sleds is the holy grail in my opinion. It would be easy to compare notes if runout was a common measurement, but it is not. The measurement is especially uncommon on high mileage sleds. There is no apparent reason to bother if the sled works, hence ignorance is bliss. The thing is, out of 100 owners of these large bores 2S, maybe one 1/4 will say they are only good for say 5,000 miles, yet that 1/4 is the loudest and drives 3/4 of the populous opinion. The worst part is, there is no data to support anything.

What we lived through from the beginning of 2021 to the end of 2022, so two full years plus, we were not privied to any data. So a high mileage 2S owner can say they are good for 10,000+ miles, and a low mileage 2S owner can say it only good until 3,000 miles with no data to help understand the reason(s) for survival or failure. In that respect I have attempted to learn what measurements appear to matter the most.

What I have been able to measure over the years is sparse, so a little here and there to at least gain a reasonable understanding. The following is an example of the measurements I have taken and some things that I could draw from. I did this in Dec of 2021 because I could finally cross the CAN/USA border.....

Below are the picture of Mike's (RX7MachZ) 800RE clutch that I drew the twelve hourly clock positions on the movable sheave with the 12 O'clock relating to the PTO Top Dead Center. I did use the degree symbol as shorthand, so I apologize for the confusion. The added numbers on the movable sheave represent the fixed sheave runout, and the numbers on the fixed sheave represent the runout on the outer perimeter of the fixed sheave which I take as a reference prior to removing the clutch.

Offset Balance/Runout

In the first picture below, note the highest runout on the fixed sheave perimeter is somewhere between the 5 and 6 O'clock position. This is a huge tell. In the second picture, note the large circle on the movable sheave that I drew an arrow to point to it. This circle is expected to be at or near BDC as shown. The crankshaft PTO stub has a large circle for the alignment mark which is near in line with the 6 O'clock position. Sorry that I do not remember how close it was to 6 O'clock, but it was close enough. Note the highest runout on the fixed sheave perimeter did closely match this position.

At near 5,000 miles I had done an extensive runout measurement on the same sled which has around 0.0035" runout on the crankshaft in the 4 to 5 O'clock position. Over 5,000 miles later (10,000+ miles total) the high spot was still near to the same position and closer to 6 O'clock.

Did BRP figure out the most likely HIGH spot on the crankshaft?

This new offset came about in 2012 for the 800RE, so 8 years after the first 1000 SDI production in 2005. How often do you see this stuff even mentioned??? It does happen, but it is rare. I recently found one that I had never seen and dated years ago, so it did happen, but again it is rare. I meant to add it here, but I need to find it again which will hopefully be less than the five years it took to find that Bill Cudney post on clutching which was brilliant. On a side note, the best way to keep a secret is to share it in the open. A secret only has its worth if it deemed top secret, so revealing anything in the open forum suggests that it is not all that relevant. In a way, that is actually a good thing.

Assume the end of the clutch shaft is five inches away from the end of the pto crankshaft end, a crankshaft runout of 0.001" will be multiplied five inches away. Now assume the taper on the clutch shaft is not perfect and has its own runout of 0.001" . Once the final clutch assembly is balanced, the heavy point shown by this balance mark will likely relate to the highest runout of the clutch shaft. So if the runout is independently measured on the clutch shaft, then the heavy spot on the final clutch assembly will likely match to the highest runout. Did you get all that? Probably not because of my poor explanation. A visual aid would make so much easier to see, but I don't have one so you will need to try and figure it out on your own.

All that I am trying to do here is to show pictures of measurement taken by me to give an idea of what I have been doing over the years.

What BRP appears to have done after marking the heavy spot on the clutch, is to index it with the lowest runout on the crankshaft. In taking the runout measurements is how I came to assume the relationship. BRP has provided an explanation that I have posted on DooTalk, but I would only find it years later after having done my own work. Ironically I have posted BRP's explanation on DooTalk, but I do not have it handy. I do remember that it did not go into the detail that I am suggesting, but it did go a long way in suggesting a balance offset. Another thing that BRP has provided, is that we are allowed to clock parts when there is a question of unbalance, or better yet we may have to if the vibrations are too high.

By the way, don't expect to find this stuff in shop manuals. BRP provides a lot of insights in their Tech Manuals and Bulletins.

Sheave Runout

The next picture shows the Sheave Runout being the highest @ 0.011" between 11 and 12 O'Clock. I like to see 0.005" of less, so a 0.011" sheave runout is getting high! I was looking at this measurement prior to BRP explaining the designed 0.024" runout on the 2017 850, but I did not yet understand the impact on the belt until BRP explained it. Until then, I was trying to find a happy medium between clutch shaft and sheave runout.

Pull&Release relationship of the belt

When I first read BRP's explanation in late Feb or beginning of March of 2017, my jaw literally dropped. Within 15 min I has read it three times, and within an hour I had realized that I had been way over my head. Now that I was beginning to understand the effects of sheave runout, what was I supposed to do about it??? I still do not have a clear answer, but I know to continue measuring. I should mention that prior to BRP's explanation, I had already figured out that a high sheave runout on the Secondary fixed sheave was a source of abnormally high vibration. But again I had yet to understand the source from the Pull&Release relationship of the belt until BRP explained it.

All of these measurements were predicated by the understanding that there was much to be learned with runout by those who had done it before me, which I mean what I learned from joining DooTalk. These guys are few and far in between, but they do exist and have posted on DooTalk. Considering that I was able to absorb their experience to push my own interest further, it is reasonable to expect you can take it much further.

Where to go from here?

Start by measuring and worry about fixing things later. DooTalk may have only one related post in 100,000, but it does exist. For example, DOOREV800 showed the possibility in correcting the sheave runout on his Secondary/QRS fixed sheave. I don't know if this is a long term solution nor if it can be applied to the Primary clutch fixed sheave, but it is a beginning.

Backwards Compatible

If you are focused on only the 1000 SDI, my hope is to provide insights that were learned from over a decade ahead that is backwards compatible. What I am posting is over 5 years old!


See less See more
Belt Tension!

I think that I am nearing the ultimate clutching posts. I am far from a clutching expert, but I do know the basics. When it comes to the 1000 SDI or even the 800 or 850 E-TECs, I find it is important to focus on the basics.

The 1000 SDI Mach Z has a clutching that can seem odd. For example, for all of its power, how does it have trouble comparing to the 850??? Ask anyone with an 850 and they typically portray it with an obscene amount of acceleration.

In comparison, the 1000 SDI has a refined thumb power. Yes, on the bold I did make that up lol But I mean it whole heatedly. The 850 was sold as a rocket, and so was the 600R. I remember bringing this up to RX7MachZ. He did not say it, but he very much eluded to I had no idea what I was talking about lol It was to the point that when I reached his place the next morning that his sled was in the front of his garage and he walked over and said to me, get your helmet on and give it a try. While I was surprised, obviously I had a good idea for what he was trying to prove. After maybe 10 min of riding and doing consecutive wot pulls, I returned to the garage with my hand up in defeat. Mike was right in the power monster of the 850 was mostly clutching.

That's the fun part of having someone like Mike to help put things into perspective. A day before I thought that BRP had done everything wrong with the 1000 SDI clutching. The thing is, there was never anything wrong with the clutching with the 434 ramps. Those ramps bring out the best of the 1000 SDI powerband with a smooth take-off and real easy to ride snowmobile!

Now go review the clutching threads that BlueMax started himself and pay close attention to what he says about the stock clutching. He essentially said there was nothing wrong with it, and there never was. Then again, BlueMax did point out something fundamentally wrong with the clutching, which was the lack of tip weight, but no need to take his word for it since BRP had already pointed out the problem as early as 2007.

So if you like how the sled rides with stock clutching and wonder how much better it would be with a stronger upshift, the only way to know is with trying mid-weighted arms and different ramps. I have the secret BRP midweight arms, but it was not any better for casual riding. BRP Racing told me the same as BlueMax, clutch for the riding I am doing. Mike (RX7MachZ) having 100 times more experience than me, said the same.

So if you want the Mach Z 1000 SDI to be the pinnacle of trails, but also win the races, I would think twice for which matters most. As a rule of thumb, the stock clutching of a Mach Z 1000 SDI with the updated tip weight is perfect for trail riding and will take any sled on the top end, hence the lake racer. So instead of getting annoyed with getting beat by 600s/800s/850s on acceleration in the first 600 feet or so, try to think of its strengths which is smooth riding and abnormally high top speed. If someone laughs, why not let him ???
See less See more
  • Like
Reactions: 1
That’s a couple really thought out posts Charles. Sure makes you not take any alignment issues for granted.
361 - 380 of 385 Posts