Sunday Feb 22 we did some clutch testing at Mr Sled's. The results were an improvement, but still not a cure for my issues so we press on.
Ulmer prescribed kit= Red spring 6-2 with Ulmer K helix and 50Y with 1T 2W heel plus 1W tip is what I started with. RPM's were definitely low. Low 8k's building to about 8500-8600.
Pink spring 6-1 shimmed with Ulmer K helix This seemed to accelerate faster as speeds crossed 80 mph. RPM's seemed to come up through the mid better.
We ended up unloading the weights to get RPM up. First the tip then the heel one washer at a time and we did come across 90 mph. Final weight config is 50Y with 1T in the heel. RPM is still a bit inconsistent, but climbed to the 8800-8900 range.
We left it there and I rode this past Saturday the 28th and Sunday March 1 with this config. It definitely pulls hard right through the 70's and across 80 mph much better now hitting 86-88 mph regularly in decent trail conditions. What I found lacking though was the "hit" out of the hole. It does not wheelie or arm pull like it did with the initial config.
Sunday March 1 I stopped by MrSled's once again and borrowed his Ulmer H helix at Allen's suggestion. Conditions were questionable so I could not really get good top speed out of it. It popped 90-91 at one point, but consistently crossed to 86-88 mph as before. RPM's are up and seemingly more consistent especially in the mid range. It now runs 8800-8900 even 9000. Primary still slipping on top end.
So with what we have changed it "feels" faster, but what it is lacking is the hit out of the hole. I put the 2 washers back in the heel. This helped with tapping the limiter on a launch with spinning. Still did not wheelie and stretch arms like it used to.
Back to Ulmer red spring at 6-2 wrap. Wheelie is back as is arm stretching. Thing I noticed though is that my downfield speed is less. The pink at 6-1 I was having trouble stopping. The speed was sneaky and continued to build. I was hitting 77 mph with the pink and 75 with the red. The acceleration of the red was a bit more boring and seemed to flatten out and the pink I was having stopping issues as it seemed to just keep pulling. I did not have time to drop back the wind on the red spring to se what it did.
What was puzzling me during my testing was how the sled was seemingly faster yet was not stretching my arms nor was I having as much difficulty with the sled veering to the side.
About all I can guess is that the arm stretch of the Red 6-2 may just be hooking up better and the fast feel of the pink 6-1 is spinning a bit more but maybe actually faster? But how can less arm pull be faster? More linear I guess?
Ulmer prescribed kit= Red spring 6-2 with Ulmer K helix and 50Y with 1T 2W heel plus 1W tip is what I started with. RPM's were definitely low. Low 8k's building to about 8500-8600.
Pink spring 6-1 shimmed with Ulmer K helix This seemed to accelerate faster as speeds crossed 80 mph. RPM's seemed to come up through the mid better.
We ended up unloading the weights to get RPM up. First the tip then the heel one washer at a time and we did come across 90 mph. Final weight config is 50Y with 1T in the heel. RPM is still a bit inconsistent, but climbed to the 8800-8900 range.
We left it there and I rode this past Saturday the 28th and Sunday March 1 with this config. It definitely pulls hard right through the 70's and across 80 mph much better now hitting 86-88 mph regularly in decent trail conditions. What I found lacking though was the "hit" out of the hole. It does not wheelie or arm pull like it did with the initial config.
Sunday March 1 I stopped by MrSled's once again and borrowed his Ulmer H helix at Allen's suggestion. Conditions were questionable so I could not really get good top speed out of it. It popped 90-91 at one point, but consistently crossed to 86-88 mph as before. RPM's are up and seemingly more consistent especially in the mid range. It now runs 8800-8900 even 9000. Primary still slipping on top end.
So with what we have changed it "feels" faster, but what it is lacking is the hit out of the hole. I put the 2 washers back in the heel. This helped with tapping the limiter on a launch with spinning. Still did not wheelie and stretch arms like it used to.
Back to Ulmer red spring at 6-2 wrap. Wheelie is back as is arm stretching. Thing I noticed though is that my downfield speed is less. The pink at 6-1 I was having trouble stopping. The speed was sneaky and continued to build. I was hitting 77 mph with the pink and 75 with the red. The acceleration of the red was a bit more boring and seemed to flatten out and the pink I was having stopping issues as it seemed to just keep pulling. I did not have time to drop back the wind on the red spring to se what it did.
What was puzzling me during my testing was how the sled was seemingly faster yet was not stretching my arms nor was I having as much difficulty with the sled veering to the side.
About all I can guess is that the arm stretch of the Red 6-2 may just be hooking up better and the fast feel of the pink 6-1 is spinning a bit more but maybe actually faster? But how can less arm pull be faster? More linear I guess?
Last edited:
Continued
Changed helix to less aggressive. The red secondary wheelies and stretches the arms. It seems to maybe slow the shift too much at the top though. The pink seems to pull through the 70's and past 80 stronger. My field test is distance limited.
I had my Gopro set up to record tach and speedo. These are single runs per setup on the field. A fair downhill slope. Not highly scientific, but they will have to suffice. The shortcomings of the gauge refresh rates are a bit apparent but it does tell a story that I've observed throughout this all. The launch is solid then it gets ahead of itself and pulls the RPM down then recovers. It has always done this in some manner. I have seen it but this is the first time that I have captured it. I used Windows media player and play/pause to change the screen capture. We are at the mercy of the sampling and refresh rates here. Where you see multiple RPM's at same speed that is exactly what the camera caught. It's not pausing there it's just fluctuating RPM's.
H helix
Pink 6-1
5mph 3530
5mph 8930
lightning quick no middle data captured then:
39 mph 8930/7710
40 mph 7710/8410
40-53 mph 8410
53-59 mph 8540/8760
65-70mph 8760/8710
70-77 mph 8890/8800/8900
red 6-2
I have no 5 mph capture, but RPM is 3080 until:
lightning quick no middle data captured then
36 mph 8680
44-45 mph 8920/8390/8140
49 mph 8140/8600
57 mph 8600/8770
64 mph 8770/8850
71 mph 8830/8870
74 mph 8960
Now there is no time reference to this, but what I can say is that both runs are about 6 seconds. I'm not sure if there is decent editing software that can put the time to the screen shot more accurately or if it is worth it.
Shimming the helix for the pink spring puts it right at the tip of the ramp. I'd prefer not to have to shim, but the Ulmer helix is not relieved for clearance.
Not sure what the curvature of the helix is, but I'm thinking at least for my setup the angle change needs to occur a bit earlier or the belly of the mid point need to be filled just a bit if there is such a thing.
I think my next step is to put some tip weight on the red 6-2 setup and see what it does, but the RPM’s are pretty good where they are. Thinking possibly dropping a couple more degrees overall may allow more weight yet to help with the slipping?
Changed helix to less aggressive. The red secondary wheelies and stretches the arms. It seems to maybe slow the shift too much at the top though. The pink seems to pull through the 70's and past 80 stronger. My field test is distance limited.
I had my Gopro set up to record tach and speedo. These are single runs per setup on the field. A fair downhill slope. Not highly scientific, but they will have to suffice. The shortcomings of the gauge refresh rates are a bit apparent but it does tell a story that I've observed throughout this all. The launch is solid then it gets ahead of itself and pulls the RPM down then recovers. It has always done this in some manner. I have seen it but this is the first time that I have captured it. I used Windows media player and play/pause to change the screen capture. We are at the mercy of the sampling and refresh rates here. Where you see multiple RPM's at same speed that is exactly what the camera caught. It's not pausing there it's just fluctuating RPM's.
H helix
Pink 6-1
5mph 3530
5mph 8930
lightning quick no middle data captured then:
39 mph 8930/7710
40 mph 7710/8410
40-53 mph 8410
53-59 mph 8540/8760
65-70mph 8760/8710
70-77 mph 8890/8800/8900
red 6-2
I have no 5 mph capture, but RPM is 3080 until:
lightning quick no middle data captured then
36 mph 8680
44-45 mph 8920/8390/8140
49 mph 8140/8600
57 mph 8600/8770
64 mph 8770/8850
71 mph 8830/8870
74 mph 8960
Now there is no time reference to this, but what I can say is that both runs are about 6 seconds. I'm not sure if there is decent editing software that can put the time to the screen shot more accurately or if it is worth it.
Shimming the helix for the pink spring puts it right at the tip of the ramp. I'd prefer not to have to shim, but the Ulmer helix is not relieved for clearance.
Not sure what the curvature of the helix is, but I'm thinking at least for my setup the angle change needs to occur a bit earlier or the belly of the mid point need to be filled just a bit if there is such a thing.
I think my next step is to put some tip weight on the red 6-2 setup and see what it does, but the RPM’s are pretty good where they are. Thinking possibly dropping a couple more degrees overall may allow more weight yet to help with the slipping?
Last edited:
Just put a different belt on there already. You are fully shifted out and even a 8DN will not take that for long. Try it. Simple thing to do. Dayco XTX 5033 is 8DN equivalent very close clutching wise to 8DN and if you want even stickier go with Gates. Other option to try is a 8JP equivalent. You have the OSP adjuster so it takes 5 minutes.
My belt is actually holding up well at this point. I do not have OSP adjuster. The std system is much simpler and defection does not change when I disassemble to make changes. Always right back to where it was.
I will definitely take the aftermarket belt under consideration, but right now I am hoping to get Ulmer to chime in as to what he would like to see next.
I will definitely take the aftermarket belt under consideration, but right now I am hoping to get Ulmer to chime in as to what he would like to see next.
No its not. You said its slipping. That is problem and I offered a very simple solution. We have proven different belts are just that. Very different. Take advantage grab the low hanging fruit and then just ride instead of beating yourself up over it trying everything under sun. Cheap easy thing to try.
As I said I will consider the belt, but it's Ulmer's kit and I'm hoping that Ulmer through MrSled and myself will come up with a solution. If they get sick of it then I'll move on. In hindsight I should have borrowed one for a quick run that Sunday when everybody was running around. As of now, I've blown enough money this season. If they recommend the belt test I'll consider it, but it sounds like I'll end up moving weight around again and I don't know that there is enough season left.
skidooslayer687
Expert
- Joined
- Aug 22, 2013
- Messages
- 251
- Location
- Almonte, Ont.
- Country
- Canada
- Snowmobile
- 2014 Yamaha Sr Viper LTX SE
X2 on the belt swap, I attempted to clutch mine with the 8jp belt, was always getting inconsistant rpm and excessive belt dust. Swapped to the 8dn and really stabilizes the rpm from what I've seen in my testing and much less belt dust.... Again that's just what I found so I would agree with cannondale27
Come to the group ride in Muni. I will have a spare for you to try if you dont want to spend the $60.
Update: Noticed that the bronze bushing in the H helix that I have on loan was not fully seated. It was a good 1/8" out. This could have skewed my results especially the red spring test as I ran w/o shims. It appears to me that this bushing would be a potential travel limiter. Might be nothing but won't know until I test it.
I hope to get back out and test to see if this setup might not match the pink spring top speed in my field testing.
And yes I'm working on Muni the 13th and 14th.
I hope to get back out and test to see if this setup might not match the pink spring top speed in my field testing.
And yes I'm working on Muni the 13th and 14th.
Last edited:
I re-seated the helix bushing in the H helix and re-ran the red spring 6-2 test.
It was about 20°f cooler. Results similar, but more top RPM and I think the bushing was blocking me out. I did manage 78 mph and RPM spent a lot of time at 8900+
What I found interesting is how much clutch I used. I'm really starting to believe that the low gearing is messing with these LE/big lug sleds.
After a few short sprints to the upper 70's:
Note no black smearing and the mark is being erased very close to the top of the shift range.
Compared to running significant time above 80 mph. Note similar shift range but blacked sheaves:
It was about 20°f cooler. Results similar, but more top RPM and I think the bushing was blocking me out. I did manage 78 mph and RPM spent a lot of time at 8900+
What I found interesting is how much clutch I used. I'm really starting to believe that the low gearing is messing with these LE/big lug sleds.
After a few short sprints to the upper 70's:
Note no black smearing and the mark is being erased very close to the top of the shift range.
Compared to running significant time above 80 mph. Note similar shift range but blacked sheaves:
Awesome now find a 300ft drag and go kick some butt!
VERY Old thread but I figured I would update my current clutching setup:
Primary
Ulmer STM weights 6 washers heel, 1 washer tip
OYO primary spring with 2 glide washers
Secondary
Ulmer H helix
TPI orange spring wound 5 and 2
8DN belt
With this setup response is wicked and I find it easier to hit and cross 80 mph than ever before. Saw 84 and even 86mph speedo which I had only ever seen previously on the grade in perfect ice conditions. I found that I had to drop the weight in the heel to get the launch RPM up. This could be due to removing friction in the primary spider pockets OR from the TPI orange spring. Prior setups tended to rev high then overshift and sag hard in the middle. Now I hit mid 8's and climb to peak of just over 9200. I plan to migrate one washer from heel to tip. I also plan to try the secondary wrapped at 3-1 at some point. Conditions are very good to excellent right now so I also need to run it for a while in varying conditions if we can get some fresh snow.
Primary
Ulmer STM weights 6 washers heel, 1 washer tip
OYO primary spring with 2 glide washers
Secondary
Ulmer H helix
TPI orange spring wound 5 and 2
8DN belt
With this setup response is wicked and I find it easier to hit and cross 80 mph than ever before. Saw 84 and even 86mph speedo which I had only ever seen previously on the grade in perfect ice conditions. I found that I had to drop the weight in the heel to get the launch RPM up. This could be due to removing friction in the primary spider pockets OR from the TPI orange spring. Prior setups tended to rev high then overshift and sag hard in the middle. Now I hit mid 8's and climb to peak of just over 9200. I plan to migrate one washer from heel to tip. I also plan to try the secondary wrapped at 3-1 at some point. Conditions are very good to excellent right now so I also need to run it for a while in varying conditions if we can get some fresh snow.
