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Discussion Starter · #1 · (Edited)
Conditions today -18c
6" to 8" of snow on my lake with slushy & tight sections.
My sled 900r xrs with only 60km on it with a 531 belt. Prior to the spring change my rpm was 76 to 7700 but mainly at 7700. Today i am now running the 170/350 primary spring.

Two other sleds with me:
Another stock 900r xrs with 1000km running the 571 belt. Max rpm 7700.

A 2021 900t xrs with a TD tune and clutching with 7,500km

All 3 sleds have 2ply tracks with 144 studs.
Mine is 1.25 lug vs there 1.5.

For the first run sled was warmed up to temp and made a few hard runs across the lake, 8000 rpm with the odd flicker down to 7900 but instantly back to 8000.

I then made several runs at 100 & 140kmph, rpm around 6800 and 7300 depending on speed. Hammer it and it would quickly climb to 78, 7900 and pull to 8000. Now if i then hit a tight section it would pull very hard but the rpm would drop off around 77 to 7800 and pull back up to 8000. Depending on the traction the rpm would fluctuate.

The other 900r xrs performed the same way but with less rpm. 7700 being max and when it would hookup the rpm would drop off to 74 to 7500 and take longer to recover back up to 7700 and more so if it hooked up again before it had recovered to 7700.

This was more noticeable when we would run the 3 sleds at the same speed say 140kmph beside each other the stock 900r when the rpm would drop off as we all hit the same tight section as we went from tight section into the 8" of snow it would fall behind.

The 21 TD tuned 900t performed pretty much the same as mine in every way with 8 to 8100 rpm In these conditions today.

Previously on hard pack and much better conditions i have a slight edge on him. But in the deep junk there doesn't seem to be much if any difference.

The other comparison we did with the stock 900r vs mine with the spring change was while traveling side by side at a set speed of around 130 kmph at a marker placed on the lake we would both hammer it the stock 900r definitely feels lazier and does not accelerate or climb to max rpm as quickly as mine.
With that said yes mine is better than it had been with the stock 170/300 spring but it still feels a little lazy to me. This is where i think a secondary spring will help.

We tried every possible combination from switching riders and sleds in order to eliminate any discrepancies.

A side from chasing the low rpm i had a chance to get into a side trail that has been destroyed by ATV'S and though it's too early to say and coming from my 2019 xrs 900t this xrs 900r with standard KYB's seem to work incredibly well. I also couldn't help but notice how flat it corners.

Hope to get to Q.C next week to pile some miles on it to see if it changes anything.
 

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great information and thank you for sharing so quickly. so now that you got the top RPM improved, did you notice a difference in speed or power from before? Or were conditions so different you could not make the comparison? And i guess in conclusion...did you get performance value out of the spring change vs just increase in RPM. Thank you again.
 

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Conditions today -18c
6" to 8" of snow on my lake with slushy & tight sections.
My sled 900r xrs with only 60km on it with a 531 belt. Prior to the spring change my rpm was 76 to 7700 but mainly at 7700. Today i am now running the 170/350 primary spring.

Two other sleds with me:
Another stock 900r xrs with 1000km running the 571 belt. Max rpm 7700.

A 2021 900t xrs with a TD tune and clutching with 7,500km

All 3 sleds have 2ply tracks with 144 studs.
Mine is 1.25 lug vs there 1.5.

For the first run sled was warmed up to temp and made a few hard runs across the lake, 8000 rpm with the odd flicker down to 7900 but instantly back to 8000.

I then made several runs at 100 & 140kmph, rpm around 6800 and 7300 depending on speed. Hammer it and it would quickly climb to 78, 7900 and pull to 8000. Now if i then hit a tight section it would pull very hard but the rpm would drop off around 77 to 7800 and pull back up to 8000. Depending on the traction the rpm would fluctuate.

The other 900r xrs performed the same way but with less rpm. 7700 being max and when it would hookup the rpm would drop off to 74 to 7500 and take longer to recover back up to 7700 and more so if it hooked up again before it had recovered to 7700.

This was more noticeable when we would run the 3 sleds at the same speed say 140kmph beside each other the stock 900r when the rpm would drop off as we all hit the same tight section as we went from tight section into the 8" of snow it would fall behind.

The 21 TD tuned 900t performed pretty much the same as mine in every way with 8 to 8100 rpm In these conditions today.

Previously on hard pack and much better conditions i have a slight edge on him. But in the deep junk there doesn't seem to be much if any difference.

The other comparison we did with the stock 900r vs mine with the spring change was while traveling side by side at a set speed of around 130 kmph at a marker placed on the lake we would both hammer it the stock 900r definitely feels lazier and does not accelerate or climb to max rpm as quickly as mine.
With that said yes mine is better than it had been with the stock 170/300 spring but it still feels a little lazy to me. This is where i think a secondary spring will help.

We tried every possible combination from switching riders and sleds in order to eliminate any discrepancies.

A side from chasing the low rpm i had a chance to get into a side trail that has been destroyed by ATV'S and though it's too early to say and coming from my 2019 xrs 900t this xrs 900r with standard KYB's seem to work incredibly well. I also couldn't help but notice how flat it corners.

Hope to get to Q.C next week to pile some miles on it to see if it changes anything.
So weird because that's what my Mach does with the stock spring. Which means my engine is pulling a lot more weight then yours.
Something very wrong with these engines. I wonder is some are low on compression or something
 

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Descending doooowwwwnnnnn
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No worries about engine, just not putting out the boost it should. PEFI had 16lbs on dyno, and couple others have stated they are not seeing the advertised 17.4lbs. (15-16lbs).
 
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Discussion Starter · #5 ·
great information and thank you for sharing so quickly. so now that you got the top RPM improved, did you notice a difference in speed or power from before? Or were conditions so different you could not make the comparison? And i guess in conclusion...did you get performance value out of the spring change vs just increase in RPM. Thank you again.
I can't comment on speed. Conditions today are far worse than any of the previous day's i have tested it on my lake.

I find because it now holds the rpm it doesn't fall on its face like it would when the rpm would drop off from 7700 and then have to try to recover back up to 7700.
We were able to see this in the other 900r that was with me today.

Absolutely i would say the performance improvement was definitely worth it.
Now with that said i only have a few hrs on it in some pretty bad conditions. But those bad conditions were helpful to show us how negatively it affected the other 900r vs mine.

I really believe a better secondary spring will really help. Now if nothing were to change from this point i would be happy with it.

Mich above compares it to his Mach. That's impossible unless he was here today.
I will know better once i get back onto decent conditions. Prior to the spring i had no problem pulling off 113mph gps.
 

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I can't comment on speed. Conditions today are far worse than any of the previous day's i have tested it on my lake.

I find because it now holds the rpm it doesn't fall on its face like it would when the rpm would drop off from 7700 and then have to try to recover back up to 7700.
We were able to see this in the other 900r that was with me today.

Absolutely i would say the performance improvement was definitely worth it.
Now with that said i only have a few hrs on it in some pretty bad conditions. But those bad conditions were helpful to show us how negatively it affected the other 900r vs mine.

I really believe a better secondary spring will really help. Now if nothing were to change from this point i would be happy with it.

Mich above compares it to his Mach. That's impossible unless he was here today.
I will know better once i get back onto decent conditions. Prior to the spring i had no problem pulling off 113mph gps.
I believe KRM switched Secondary springs, not sure to what. Maybe he'll chime in and let us know. I'll leave my 150/370 in it now. The difference is I have 897 ramps compared to your 880 ramps. I may have to pick a set of those 880's up. Dan seems to like the 880 ramps better also.
 

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Discussion Starter · #7 ·
I believe KRM switched Secondary springs, not sure to what. Maybe he'll chime in and let us know. I'll leave my 150/370 in it now. The difference is I have 897 ramps compared to your 880 ramps. I may have to pick a set of those 880's up. Dan seems to like the 880 ramps better also.
If you don't plan to use your launch control maybe. It's so early i would hold up on switching out those 897. If this truly turns out to be a problem you would hope doo steps up to make it right.
 

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If it's pulling rpm back your problem is 100% in the secondary. Likely to much angle. Cheap fix is the spring, to be fast you need to correct the degree issue and not bandaid it with a spring. Certainly will feel like the weights are to heavy but it's not for sure, lighter weights or more primary spring is a bandaid as well. Clutching 101.
 

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Discussion Starter · #10 ·
did you try the green green compression with the 47/40 this can flatten your shift curve
Comes with the green green. 👍
 

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If it's pulling rpm back your problem is 100% in the secondary. Likely to much angle. Cheap fix is the spring, to be fast you need to correct the degree issue and not bandaid it with a spring. Certainly will feel like the weights are to heavy but it's not for sure, lighter weights or more primary spring is a bandaid as well. Clutching 101.
Could also be too much tit weight, or the weight profile itself. Turning with the secondary is after you have the desired RPM’s .
 

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Could also be too much tit weight, or the weight profile itself. Turning with the secondary is after you have the desired RPM’s .
How do you know when you have the best primary set up and to move to the secondary?

because secondary change and cause more rpm up top also
 

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How do you know when you have the best primary set up and to move to the secondary?

because secondary change and cause more rpm up top also
Simple answer, if you hit peak rpm and it pulls back.. its not the primary, it's impossible to hit peak rpm with too heavy of weights. So simple right. Torque load has taken over causing rpm drag.
 

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Great to hear that changing primary spring helped!

Sounds that you are still having backshift issues with secondary. I can see from the parts catalogue that there is 180-303 green spring on secondary.

I would next try to go with Dalton Red spring 205-310. Should help with backshift and keep rpm more consistent.
 

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I went 44/33 and a black/black spring , I wouldn’t recommend getting into the primary on the Mach z and changing the weights, the helix seems to be my problem maybe cause I’m over studded.
installed bills pb80 over drive kit last night I’ll test first of the week when the weather changes
 

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Discussion Starter · #16 ·
Great to hear that changing primary spring helped!

Sounds that you are still having backshift issues with secondary. I can see from the parts catalogue that there is 180-303 green spring on secondary.

I would next try to go with Dalton Red spring 205-310. Should help with backshift and keep rpm more consistent.
Great to hear that changing primary spring helped!

Sounds that you are still having backshift issues with secondary. I can see from the parts catalogue that there is 180-303 green spring on secondary.

I would next try to go with Dalton Red spring 205-310. Should help with backshift and keep rpm more consistent.
Thanks for the input.
P.M. sent.
 

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Discussion Starter · #17 ·
I went 44/33 and a black/black spring , I wouldn’t recommend getting into the primary on the Mach z and changing the weights, the helix seems to be my problem maybe cause I’m over studded.
installed bills pb80 over drive kit last night I’ll test first of the week when the weather changes
So not to muddy the waters my spring change was done to my 900R xrs i can't comment on what that spring would do for the Mach since it has a different profile to the arms.
 

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there is no black/black spring
most of the springs now come all black
and have in fine print have the part number and color code
I believe the days of real color paint on springs is over at brp
 

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Discussion Starter · #19 ·
there is no black/black spring
most of the springs now come all black
and have in fine print have the part number and color code
I believe the days of real color paint on springs is over at brp
I took it as Black 417127039
157\303

Font Material property Pattern Symmetry Number
 

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Yes 157/303

ill be honest I’ll probably end up blue/ blue and a stiffer primary spring
hopefully Be able to run the 170/400 and the DTYR-2 weights
 
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