nitris223
TY 4 Stroke Junkie
- Joined
- Nov 18, 2012
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- 589
- Location
- Yorkton Saskatchewan
- Country
- Canada
- Snowmobile
- Yamaha Nytro MTX
Rode the MTX for the first time yesterday. Right now I have the track trimmed to 1 3/4", 18/40 gearing going to 20 tooth top maybe. Stock weights, 14.5 rollers, OPO primary spring, stock secondary spring set 3 and 3 and a Shockwave Helix set at 2 turns from full out. Ulmer figured that would be about 45 degrees on the shockwave.
When I punch it from a dead stop it almost seems like it is slipping or something . I first thought it was ratcheting but very mild. More like a shutter . I know it was not the track ratcheting, felt that before on sleds. I expect it to torque off the start and I almost fall forwards when I punch it but as soon as I hit about 25-30 mph it pulls like a freight train.
I have seen 87mph on the speedo but I think the RPMS are a bit low.8950 is what I have seen. Never went over 9000 and fell back to 8950. Just climbed to 8950. Rolling along and nail the throttle it pulls strong. Just the bottom end seems to be way off. Is this more of a Shockwave helix thing. I have seen lots for sale over the years since they came out. I think they are a good idea but are they any good..
I have a stock 43 degree yamaha helix kicking around but I figured I would try this shockwave helix first seeing how it came with one of the sleds .
When I punch it from a dead stop it almost seems like it is slipping or something . I first thought it was ratcheting but very mild. More like a shutter . I know it was not the track ratcheting, felt that before on sleds. I expect it to torque off the start and I almost fall forwards when I punch it but as soon as I hit about 25-30 mph it pulls like a freight train.
I have seen 87mph on the speedo but I think the RPMS are a bit low.8950 is what I have seen. Never went over 9000 and fell back to 8950. Just climbed to 8950. Rolling along and nail the throttle it pulls strong. Just the bottom end seems to be way off. Is this more of a Shockwave helix thing. I have seen lots for sale over the years since they came out. I think they are a good idea but are they any good..
I have a stock 43 degree yamaha helix kicking around but I figured I would try this shockwave helix first seeing how it came with one of the sleds .
akvector
TY 4 Stroke Junkie
the 14.5 rollers do not work well with the stock weights. You either need to change weight profile to work with the 14.5s or go back to stock rollers.
nitris223
TY 4 Stroke Junkie
- Joined
- Nov 18, 2012
- Messages
- 589
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- Yorkton Saskatchewan
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- Canada
- Snowmobile
- Yamaha Nytro MTX
First I have heard of the 14.5 rollers not working with stock weights. Lots of post about guys just changing the rollers and nothing about weight changes. SB just sells a comfort kit and it is just 3 rollers and spring change.
loudelectronics
TY 4 Stroke Guru
On my mtx see I am running stock gearing, stock rollers, stock spring and stock secondary everything. For the weights I am running super Rats. Today I saw 91.4 mph and the rpms would be around 8700. For reference I guess. Sounds like you changed a whole lot all at once.
nitris223
TY 4 Stroke Junkie
- Joined
- Nov 18, 2012
- Messages
- 589
- Location
- Yorkton Saskatchewan
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- Canada
- Snowmobile
- Yamaha Nytro MTX
Changed the rollers and spring for lower engagement. Spring finish is the same as the stock mtx spring. Helix I went by what ulmer said would work. From what I can find which is not a lot it seems like most guys that set up a mtx for the flat land low elevation are using a 45 or a 43 degree helix. The dealer here does nothing but load up the weights. There has to be something better the just load up the weights. Not looking so much for a drag racing set up. More of just a good pull from the bottom to the top. It is a real pita to load the sled drive 5 miles and test one thing at a time. To bloody cold out there to be changing a helix or springs on the trail.
Ditch the 14.5's or change the weights.
nitris223
TY 4 Stroke Junkie
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- Nov 18, 2012
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- 589
- Location
- Yorkton Saskatchewan
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- Canada
- Snowmobile
- Yamaha Nytro MTX
I always seem to find this crap out after spending over $150 on rollers. The search feature sucks on this forum. I tend to get everything that I am not looking for. So what is the recommended clutch set up for the mtx for low elevation. What weights would I need for the 14.5 rollers. There is nothing new in the tech section for clutch set ups since 2008 .
loudelectronics
TY 4 Stroke Guru
People will have lots of recomendations for you.
Here is what I tried:
I wanted everything to be quick swap out for when I ride prairie to when I ride mountain.
I used the rollers and weights out of my xtx for starters. It worked ok but I still was hitting rev limiter with the exhaust. So more weight was needed.
I then put back the 17.5 mm rollers and installed the super rats. This worked much better. I still have a bit of over rev when I hit the throttle but my rpm are in check on long wot pulls and hittin 150 kph which is right where my gearing says I should be. I never did get to try the 14.5 rollers as I sold the xtx.
Not sure how to fix the over rev when I stab the throttle with the rats. Might have to load more weight in the channel.
Sled pulls pretty good, will wheelie up hills and lift skis and carry them for quite a ways on the flats.
Here is what I tried:
I wanted everything to be quick swap out for when I ride prairie to when I ride mountain.
I used the rollers and weights out of my xtx for starters. It worked ok but I still was hitting rev limiter with the exhaust. So more weight was needed.
I then put back the 17.5 mm rollers and installed the super rats. This worked much better. I still have a bit of over rev when I hit the throttle but my rpm are in check on long wot pulls and hittin 150 kph which is right where my gearing says I should be. I never did get to try the 14.5 rollers as I sold the xtx.
Not sure how to fix the over rev when I stab the throttle with the rats. Might have to load more weight in the channel.
Sled pulls pretty good, will wheelie up hills and lift skis and carry them for quite a ways on the flats.
nitris223
TY 4 Stroke Junkie
- Joined
- Nov 18, 2012
- Messages
- 589
- Location
- Yorkton Saskatchewan
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- Canada
- Snowmobile
- Yamaha Nytro MTX
I went with the 14.5mm roller and the different spring because that is what I have read that worked for lower engagement to make it easier to start off and loading onto a trailer. It does make a big difference with loading on a trailer. No more spin or jump forward.
I don't really think it is a weight problem, I think it is slipping in the secondary . That is kind of what it feels like. My rmps don't drop when I pin it. it is just like a flat spot in the take off then it fells like it grabs and goes. 3 qne 3 on the helix should be 90 degree twist right.
The one time I did get off into some deeper snow it did lose some pull but it was a nasty piece of the field and I was not taking my eyes of what was ahead of me to look at the tach.
When we stopped at a warm up shack I did check the clutches for heat and I could hold my hand on the primary and secondary , the secondary was a bit hotter. Could still hold my hand there for 30 seconds or more.
i have another secondary spring that came with the shockwave helix but I am not sure what make it is. All black with purple splashed here and there. Almost looks like a cat spring.
Going to check the spring setting again. I did find it harder to install the 45 degree helix on the wifes sled compared to installing the shockwave on my sled.
I don't really think it is a weight problem, I think it is slipping in the secondary . That is kind of what it feels like. My rmps don't drop when I pin it. it is just like a flat spot in the take off then it fells like it grabs and goes. 3 qne 3 on the helix should be 90 degree twist right.
The one time I did get off into some deeper snow it did lose some pull but it was a nasty piece of the field and I was not taking my eyes of what was ahead of me to look at the tach.
When we stopped at a warm up shack I did check the clutches for heat and I could hold my hand on the primary and secondary , the secondary was a bit hotter. Could still hold my hand there for 30 seconds or more.
i have another secondary spring that came with the shockwave helix but I am not sure what make it is. All black with purple splashed here and there. Almost looks like a cat spring.
Going to check the spring setting again. I did find it harder to install the 45 degree helix on the wifes sled compared to installing the shockwave on my sled.
..SNAKEBIT..
Expert
3 and 3 I thought would give you 60' twist
nitris223
TY 4 Stroke Junkie
- Joined
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- 589
- Location
- Yorkton Saskatchewan
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- Canada
- Snowmobile
- Yamaha Nytro MTX
Had everything all screwed up. 3and 3 is 60 . My mistake , Yamaha clutching always screws me up, use to Polaris clutching the last few years. I had the spring at 2 and 3 which is only 50 degrees. Had the shockwave helix set wrong. Ulmer told me 2 turns out and I assumed from the top with the ring flush with the threads. It is 2 turns from the bottom is what he was meaning. Anyway I used my machinist level and figured I had it set at 54 degrees so I turned it in until I was at 45 degrees which is about 3/4 of a turn from full bottom. Now I just have to wait for warmer weather and all this Christmas stuff to get over and done with. Looks like a week of cold weather coming are way. Still pulled 8950 rpm on hardpack.
knocksum
Extreme
With that 18/40 gearing you are going to spin track and slip the belt into the secondary pre mature. Tighten up the secondary 10 degrees. Maybe more. Your rpms will come back. You will also eliminate that boggy feel when you hit deeper snow as the clutches will work better together.
nitris223
TY 4 Stroke Junkie
- Joined
- Nov 18, 2012
- Messages
- 589
- Location
- Yorkton Saskatchewan
- Country
- Canada
- Snowmobile
- Yamaha Nytro MTX
Going to install a 20 tooth top gear. Would I still need more then 60' twist now that I have the helix set right. Got the extra gear to try.
Alatalo
TY 4 Stroke Master
My first impression from your own description was a slipping secondary. Part because of your ratchet-like description, part because of the stock secondary spring at 60 degrees combined with a steeper than stock helix. This just sounds like not enough side force on the belt. I was just about to post it when I did see you figured it out by yourself.
Just for reference, I am running a setup based on the green Arctic Cat secondary spring. This is a relatively soft spring with lots of preload for compression as well as twist. Except for this I use the stock helix, stock primary spring and the stock weights loaded for 8800-8900 rpm. Works awesome for flatland powder riding. Never slips the secondary, especially not in the situations when you are just about to get stuck (the worst part about the box stock setup...).
Just for reference, I am running a setup based on the green Arctic Cat secondary spring. This is a relatively soft spring with lots of preload for compression as well as twist. Except for this I use the stock helix, stock primary spring and the stock weights loaded for 8800-8900 rpm. Works awesome for flatland powder riding. Never slips the secondary, especially not in the situations when you are just about to get stuck (the worst part about the box stock setup...).
clatla
Pro
I bought a setup from Scott (SCMURS) with OFT Racing a while back. There is nothing on the website so no need to look. Shoot him a PM. The setup is SPOT-ON! One for elevation and one for sea-level. The only difference are the weights. Changed weights, rollers, springs and tightened up the secondary. All Yami parts.
