Setting helix angle

[auto2665]

Where are the numbers 1-2-3 located on the driven clutch for setting helix angle? I pulled the clutch apart to clean it up and thought it would be labeled a little better. Also, can someone explain the difference between a single vs dual angle helix? When is one preferred over the other.

 

[Mtnviper]

The numbers corrolate to the amount of twist or preload on the secondary spring.
The is a 1,2 and 3 in the secondary fixed sheave and 3, 6 and 9 in the helix. On Yamahas each number equates to 10 degrees. For example the 2 would be 20 degrees, 6 = 60 degrees, etc.

When you install the secondary spring, the tabs will line up with a numbered hole.
For example if you install the spring so that the tab is in the #2 hole in one end and #6 hole in the helix. You would add the 2 and 6 to come up with 8 or 80 degrees of twist/preload.

Decreasing secondary spring preload (for example 70 degrees) increases upshift speed, reduces belt side pressure and decreases backshifting (clutching down shifting effect)
Increasing secondary spring preload (for example to 90 degrees) slows the upshift rate, increases belt pressure and improves back shifting.

A steeper helix angle (for example 47 degrees) will have a faster up shift, but less belt side pressure (belt pinch) and have a slower back shift.
A shallower helix angle (for example 39 degrees) will have a slower upshift, but provide more belt pinch and have better back shift.

For drag racing normally you run less spring preload and a steeper helix.
For corner to corner blasting or off trail/mountain riding you run more spring preload and a shallower helix.

A multi-angle helix allows the secondary to shift out a variable rate. For example a 43-39 helix acts like a 43 degree helix at slower speeds, then as the sled speeds up, the secondary shifts into the 39 degree finish angle. This allows for a quicker up shift at slower speeds, then slows the shift rate a high speed to help keep engine rpm up and provide more belt pinch on the top end.

On my XTX I ran a 43-39 helix and what it does is help prevent over-rev on the bottom end while help prevent under-rev at higher speeds. This allows for a "straighter shift" which means the rpm stays more consistant as the sled accelerates from slow to high speed!

Bill

 

[auto2665]

Thank you for such a complete response. I still cant find the 1,2,and 3 labeled on the secondary. Any chance someone can post a picture where I should be looking?

 

[Dimebag]

Here you go. I know its hard to tell where the numbers are.

You can see me pointing with a screwdriver on hole 3 in the picture.

From there you go counter-clockwise to find the number. That means the hole in top of the picture with the two black "X" is number 2.

 

[nytrozula]

No wonder why he can't find the numbers!

 

[snowbeast]

The numbers corrolate to the amount of twist or preload on the secondary spring.
The is a 1,2 and 3 in the secondary fixed sheave and 3, 6 and 9 in the helix. On Yamahas each number equates to 10 degrees. For example the 2 would be 20 degrees, 6 = 60 degrees, etc.

When you install the secondary spring, the tabs will line up with a numbered hole.
For example if you install the spring so that the tab is in the #2 hole in one end and #6 hole in the helix. You would add the 2 and 6 to come up with 8 or 80 degrees of twist/preload.

Decreasing secondary spring preload (for example 70 degrees) increases upshift speed, reduces belt side pressure and decreases backshifting (clutching down shifting effect)
Increasing secondary spring preload (for example to 90 degrees) slows the upshift rate, increases belt pressure and improves back shifting.

A steeper helix angle (for example 47 degrees) will have a faster up shift, but less belt side pressure (belt pinch) and have a slower back shift.
A shallower helix angle (for example 39 degrees) will have a slower upshift, but provide more belt pinch and have better back shift.

For drag racing normally you run less spring preload and a steeper helix.
For corner to corner blasting or off trail/mountain riding you run more spring preload and a shallower helix.

A multi-angle helix allows the secondary to shift out a variable rate. For example a 43-39 helix acts like a 43 degree helix at slower speeds, then as the sled speeds up, the secondary shifts into the 39 degree finish angle. This allows for a quicker up shift at slower speeds, then slows the shift rate a high speed to help keep engine rpm up and provide more belt pinch on the top end.

On my XTX I ran a 43-39 helix and what it does is help prevent over-rev on the bottom end while help prevent under-rev at higher speeds. This allows for a "straighter shift" which means the rpm stays more consistant as the sled accelerates from slow to high speed!

Bill

Hi,is this 43/39 a yamaha helix that i can buy at a yamaha dealership,that is what i would like to try. maybe you may even have one f/s. Pete

 

[1975FA]

I just put a Ulmer clutch kit in my sled today and my secondary was not marked like the service manuel shows. The factory setting on an RTX is hole 2 so I marked that hole where the spring was 2 and then marked the next tighter hole 3. The least spring tension hole has to be 1. This is all good providing the previous owner never changed the stock setting.

 

[Mtnviper]

[/quote]Hi,is this 43/39 a yamaha helix that i can buy at a yamaha dealership,that is what i would like to try. maybe you may even have one f/s. Pete[/quote]

The 43/39 helix is an aftermarket unit. The one I have is a billit helix made by Dalton and if I remember correctly Allan at Ulmer racing had them in stock.

Bill