MTX Clutch tuning - Turk / SRX / Len / others help needed.

[double a ron]

Ok, I ride from 6000-8000 feet primarily, so from the stock setup I installed:

- Yamaha Yellow-Pink-Yellow primary spring
- 14.5mm rollers
- 8DN-10 weights, 10.3 mm steel inner and 10.3mm aluminum outer, 44.7 grams overall weight.
- Yamaha black/silver secondary spring
- Stock 43° helix @ 70° wrap
- 18 /40 gearing
- 162x2.25 CE track

With this setup I was overrevving slightly at elevation, peak at about 9200 and 9100 after shift.

I removed the aluminum outer and put in a steel outer, the lightest I could get it to was 46.2 grams before I had no more material to take down, I knew it was heavy but ran out of tuning time and had to run it like that.

This wouldn't be that big of an issue, but the mistake I made was I made two adjustments at once, the weight, and I also chucked on an older hauck helix I had lying around from my old sled, it has no markings, but as far as I can remember it is a straight cut 46. I went to a 60° wrap on this new helix at this time, and have upped to 70° the last time out.

I still need to remove some weight, I am revving right now at about 81-8200 with 46.2grams, and a 70 ° wrap, but I am looking for some recommendations from the experts. I have planned to take out .6 to .7 of a gram out of the tip, does this sound right?

My other question is did I do the right thing with the wrap on the secondary with the new helix? I am slightly ignorant of the effects of helix angle, truth be told I just had to put that shiny helix on, but should I have stuck with the 43°?

Thanks all in advance.......a

 

[1049triple]

You would want to be at 70° wrap. Since you put more weight and a more agressive helix, your sled will want to upshift faster so the rpm will be lower. What are the RPMs right now with your new setup? If they are slightly too low, put your helix at 70°. And if they are again too low, then come back to the stock 43° at 70°wrap. Remember it is a Mountain sled you have and you dont want to run an helix that is too agressive.

 

[Turk]

Hauck usually makes agressive dual angle helix,s.
Go back to your original; helix
Change inner to a 13.3 steel(3.1 gram)
change outer to a 10.3 steel(2.4 gram)
You may have to tighten secondary 10 degrees.
Not knowing the helix angle is like a blind man trying to play darts.

 

[double a ron]

Sorry, I did change to a 70° wrap the last time out at 7500ft and I was reving at 8250 peak and 8100 steady.......

So lets assume I didn't put the helix on, go back to my original setup, 44.7grams and 43° helix @ 70°. How much weight should I have added to get down to 87-8800rpm?

Thanks for the help so far guys......

 

[double a ron]

You guys have me thinking about the helix, so I did a bit of photoshop work, and I agree this is a dual helix, but it looks like a 43/46.

Regardless I am goign to chuck the stock one back on at 70°, any recommendations on what I should adjust my weights to?

 

[double a ron]

Hauck usually makes agressive dual angle helix,s.
Go back to your original; helix
Change inner to a 13.3 steel(3.1 gram)
change outer to a 10.3 steel(2.4 gram)
You may have to tighten secondary 10 degrees.
Not knowing the helix angle is like a blind man trying to play darts.

Thanks Turk, I agree on your last statement......


What is the reason for going heavier on the inside then what I have now?

I also have a 10.3 steel outer right now, will I still not be a bit low in RPM unless I reduce that one?

 

[Turk]

For mountain riding you want heavy inner & lighter outer for low end belt grab & better backshift in deep snow & on a climb. If you laid out those helix,s side by side instead of on top of eaqch other it would be easier to see the difference in angles with your lines drawn thru it.

 

[double a ron]

No worries on the helix, I am going back to the 43°.

I'll give it a try, but I guess my thinking is that if I am not changing the outer weight from what it is now (10.3mm steel) then my peak rpm's will still be a bit low.

Thanks Turk.
A

 

[Turk]

Re-read my post. Your changing outer from 10.3 al to 10.3 steel & going up 1.8 grams.

 

[double a ron]

Gotcha.

In my first post I stated that I already changed the outer to 10.3 steel, bringing the total weight to 46.2 and now my rev's are about 600 low. But then again I have the helix issue.

I am really screwed. What I will take from your post is that I should go back to stock helix and run it again and see where I am at, as I have already gone up 1.5grams total from the base setup.......

Sorry for the confusion Turk, I appreciate your advice........a

 

[Muleskinner]

Why such light weights? I looked and my Viper came with 8DN-10's. The stock weights in my Nytro MTX are 24 grams heavier. I was considering swapping the Heel Clicker kit from my Viper onto the Nytro but thought it wouldn't work. Turk, should I try it?

 

[Turk]

You can run a lot lighter less aggressive weight at higher elevation. It will smack off the rev limiter big time at flatland elevation.

 

[Muleskinner]

I assume the profile is way different? I am changing a couple grams and moving 1-200 rpm. I guess I'll try the heel clickers and see what I get.