• Don't miss out on all the fun! Register on our forums to post and have added features! Membership levels include a FREE membership tier.

Mountain sled clutch behavior

B
Jan 26, 2013
79
10
8
Hi all,
I am working on clutching a Yamaha mountain Max with some extensive modification done to it. It's been stretched to a 151 with an EZ-ryde skid and some gearing changes. The guys on TY haven't really been helpful, most of them are flatland riders and don't seem to understand how it's suppose to work.

I'm looking for advice on the upshift/back shift characteristics I should look for. Last year I couldn't get full upshift because the secondary was over sprung. I ride in New England and for how I'm setup there is nothing in the book to use as a starting point so it is all custom. I think I have a handle on it, and some different springs, weights and helix to try this year. For the Yamaha guys I'll list all the specs
2002 mountain Max 700
8 tooth drivers, 20/39 gearing. Book list 23/40 gearing for 1500-3000' so I'm way out of their spec.

8cr weights, 4.5g rivets in both holes. Also have 8dn-20's if I need more weight.

I have a www, ywy, wsw and wgw primary springs to play with
In the secondary I have a silver, green and red secondary spring 43 and 51/43 helix.
I am starting with the wgw primary spring and the green secondary on the 51/43 helix at 60 degrees.
What the response I should be looking for when I know it's right? When the sled was still a 141 it still had flat clutching and wasn't very snappy.

Thanks all

Edit: starting with the wgw spring, wsw is softest I have going to start in the middle.
 
Last edited:
B
Jan 26, 2013
79
10
8
Forgot to mention last year max rpm was around 8900-9400 my target is 8300. The sled felt like all the acceleration was in the motor and none in the drivetrain. When climbing I couldnt pin it or I would over rev and I was afraid I would blow the motor up. Obviously with mountain riding I need to be able to hold it pinned and have the clutches load the motor accordingly.
 
V

volcano buster

Well-known member
Nov 26, 2007
4,221
1,613
113
Stayton Oregon
You are running a triple so you want it to rev quick as the twins tend to have more low end torque to sling heavier weights.

I would imagine you are revving very fast when you over rev. I would think you could tolerate possibly 4 more grams of weight to get the peak rpm's down, but then it may start to rev a little sluggish. You would likely need to change primary springs to control the extra weight. I am not familiar with the Yammie terminology or weights, but you need to add more to it for sure.
 

worx53

hotrodsledshop.com
Lifetime Membership
Jul 15, 2009
160
55
28
www.hotrodsledshop.com
Put a set of Thundershift arms in it. They are a great profile to complement the motor and are fully adjustable instead of the stone-age rivets in stock yam weights. overreving and and lack of full shift indicates the flyweight was not heavy enough. If you put more weight in the tip it may shift out all the way and your secondary spring might have worked properly. Step #1 is a good set of adjustable arms and go from there.
 

kanedog

Undefeated mountain clutching champ of the world.
Lifetime Membership
Oct 14, 2008
3,103
3,855
113
60
Primary-controls rpm
secondary-controls backshift.
Take notes what each change did. Easy peasy but it takes time.
And patience.
 
B
Jan 26, 2013
79
10
8
Primary-controls rpm
secondary-controls backshift.
Take notes what each change did. Easy peasy but it takes time.
And patience.



Little testing vid.

rpm's are just a little short. I could over spring the secondary to 80 degrees but that's just a band aid from what I've read. Now if it (cough) change the tip weight back to a 3.6g I'll be at stock, and should get my couple hundred rpm back. Then all I did was change my engagement (for the better) and lose a little total force from stock. If that doesn't do it, then I can over spring the secondary.

final results: 8cr weights 4.5/4.5 w-g-w spring rx-1 51/43 progressive helix at 70 degrees on a green spring. I've never changed the secondary spring. as far as I can tell it's 12 years old just like the sled is. Maybe turning it up will get it back to the tension of a new one at the proper setting.
 
C
Feb 23, 2009
49
4
8
MM

YES I WOULD GO WITH A ROLLER SECONDARY WITH A YELLOW CAT SPRING AND A STRAIGHT 50 HELIX ,WORKED VERY GOOD ON MY 99 700 MOUNTAIN MAX OH STOCK AND MODDED.YESYOU NEEDMRE WEIGHT NEAR THE TIP.
 
Premium Features