Ulmer Dyno

[sideshowBob]

It is great that Allen is sharing all this info with us! Thanks!

On my SW, and also my S/C Apex, I have always used relatively soft primary springs for very low engagement, fairly light weights, and steeper secondary helixs. Since getting my SW I have only used Dalton components and an Apex primary.
My sled in not studded [1.75" back country], used for high mileage day trail riding, and has worked very well for me with low belt temps, great fuel economy, and no durability issues.

Works for me

 

[STAIN]

How does the Dalton helix compare to STM or stock I always run Dalton just because I have so many of them I try to stick to one brand because of the differences.

It looks as though the STM helix's are @ 6 degrees higher.
I am under the assumption that Dalton helix's are the same as stock.

It is great that Allen is sharing all this info with us! Thanks!

Agree!!! It is awesome he takes time to share this info with the members here.

 

[Srxspec]

Is there a reason you use STM helix's that don't match stock angles vs a Dalton that does seem to match? Price? Availability? Quality?
Dalton seems to be @ $30 higher

I've been using STM weights since 2004, when Rick @ Advant-Edge closed down, we asked STM to make our helix's as well. I can call or send a text and have anything I need in a day or 2 is really why.

 

[Srxspec]

How does the Dalton helix compare to STM or stock I always run Dalton just because I have so many of them I try to stick to one brand because of the differences.

Dalton helix will match OEM Yamaha angles. STM will be 6 degrees steeper. If you bought a Dalton 35, it will shift virtually the same as OEM. If you buy a STM 35, it will shift closer to a 41 degree angle.

 

[Doc Harley]

I didn't want to share this with the group, in fear of the, "YOU'RE DOWN ON POWER!!!" comments.
305hp @ 74.6g....light is right!

 

[BADSLED]

Dalton helix will match OEM Yamaha angles. STM will be 6 degrees steeper. If you bought a Dalton 35, it will shift virtually the same as OEM. If you buy a STM 35, it will shift closer to a 41 degree angle.

Allen, I was under the impression Yamaha OEM helixes changed from 35deg in early models to 35/39deg in last 5 years of so. Did they go back to the 35 degree in '24 or '25 model years?

 

[Srxspec]

Yamaha still offers the OEM 35 degree helix, even today. 2019 and newer sleds come with a 35/39.

OEM helix are marked, but you've got to be careful because some 2019 & 2020 models are ink stamped rather than marked like normal.

In 2017 & 2018 the Sidewinder came with a 8KC50 (35 degree straight cut helix). They offered a 37 & 39 as well (8KC70 & 8KC90). From 2019 on the 129, 137, 141, 146 units all come with a 35-39 helix, it is either marked 8KC70 (I believe this was in 2019 & 2020) and now marked 8MA10 I believe for 2021 and further.

8KC50 = 35
8KC70 = 37
8KC90 = 39
8MA10 = 35/39

 

[Srxspec]

Yamaha still offers the OEM 35 degree helix, even today. 2019 and newer sleds come with a 35/39.

OEM helix are marked, but you've got to be careful because some 2019 & 2020 models are ink stamped rather than marked like normal.

In 2017 & 2018 the Sidewinder came with a 8KC50 (35 degree straight cut helix). They offered a 37 & 39 as well (8KC70 & 8KC90). From 2019 on the 129, 137, 141, 146 units all come with a 35-39 helix, it is either marked 8KC70 (I believe this was in 2019 & 2020) and now marked 8MA10 I believe for 2021 and further.

8KC50 = 35
8KC70 = 37
8KC90 = 39
8MA10 = 35/39

And the best thing you could do with that 35/39 is take it off and throw it into the bottom of your local lake or river......

 

[sideshowBob]

And the best thing you could do with that 35/39 is take it off and throw it into the bottom of your local lake or river......

Agree!
LOL...I removed it off my 2019 XTX before I ever rode the sled and its been collecting dust in "Parts Heaven ever since.

 

[KnappAttack]

I didn't want to share this with the group, in fear of the, "YOU'RE DOWN ON POWER!!!" comments.
305hp @ 74.6g....light is right!

Well that depends on what you’re running for the rest of the clutch recipie along with the style of clutch arms being used. Belt, springs and helix. If your running a 8jp, Dalton primary arms, 35 helix and orange Dalton spring at 80-90 and a blue Dalton spring in the primary or heavier, then your way down on power and have issues there. So like Allen said, there’s more than one way to get it done. Allen’s using more aggressive STM weights and their 6 degree larger cut helix’s. So to just throw out ramp arm weights means nothing, absolutely nothing.

 

[Doc Harley]

Well that depends on what you’re running for the rest of the clutch recipie along with the style of clutch arms being used. Belt, springs and helix. If your running a 8jp, Dalton primary arms, 35 helix and orange Dalton spring at 80-90 and a blue Dalton spring in the primary or heavier, then your way down on power and have issues there. So like Allen said, there’s more than one way to get it done. Allen’s using more aggressive STM weights and their 6 degree larger cut helix’s. So to just throw out ramp arm weights means nothing, absolutely nothing.

Mike, its been my opinion that heavy springs & more arm weight = more probability of failure within the yamaha primary.
These factory yamaha sidewinder primaries can live a good life when utilizing a lighter load & general maintenance.
Not knocking the advantages of aftermarket clutches at all.

 

[stone88]

Well that depends on what you’re running for the rest of the clutch recipie along with the style of clutch arms being used. Belt, springs and helix. If your running a 8jp, Dalton primary arms, 35 helix and orange Dalton spring at 80-90 and a blue Dalton spring in the primary or heavier, then your way down on power and have issues there. So like Allen said, there’s more than one way to get it done. Allen’s using more aggressive STM weights and their 6 degree larger cut helix’s. So to just throw out ramp arm weights means nothing, absolutely nothing.

Agreed to many variables to say a certain weight is correct

 

[Srxspec]

Thanks again Allen. Being a Cat guy, I'm curious where your Yami set-up compares to a Cat clutch set-up? I'm sure you've played with a few (I know of at least one lol)

I just went and looked in my notes, this was a stock 2024 T-Cat but has a 1-1/2" track studded. Used a 85/225 primary spring & 59 gram weights, stock secondary, stock belt.

 

[STAIN]

I just went and looked in my notes, this was a stock 2024 T-Cat but has a 1-1/2" track studded. Used a 85/225 primary spring & 59 gram weights, stock secondary, stock belt.

You dropped 7 grams off the primary weight? I knew those Cats where clutched too heavy but that's a lot!!!
Did you use an STM weight with a more aggressive profile?
I was also looking at that spring, 85-225, to smooth out the engagement on my Riot

 

[Srxspec]

You dropped 7 grams off the primary weight? I knew those Cats where clutched too heavy but that's a lot!!!
Did you use an STM weight with a more aggressive profile?
I was also looking at that spring, 85-225, to smooth out the engagement on my Riot

STM aggressive profile, same weights I use in a Yamaha.