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nytro clutching

Joined
Apr 3, 2006
Messages
161
Age
51
Location
Prince Edward Island, Canada
Country
Canada
Snowmobile
2011 Nytro XTX, Hurricane Exhaust, K&N, Pcv, Autotune, Pod300, Star Suspension,
2018 Sidewinder, TD Max Spool 17, CAI, TD 3 Inch Stock Muffler Mod, 3Bar, BOV
LOCATION
Prince Edward Island, Canada
I recently purchased a 2011 nytro xtx. The owner bought it from a dealer in 2016 and knew nothing about the sled other then get on and drive.
The original owner upgraded the sled with a 1.75 back country track, full Hindle exhaust and a pc5. No airbox mod. The sled is also clutched.
I noticed driving(little seat time) that there was a lot of popping out of the sled. I ran a 2008 apex 121 with 1,25 track and studded from a rolling start 20/30 mph and walked away and was about 4 lengths ahead at 103mph so the sled runs well.
I seen a lot of people and talking to a few to do the airbox mod...I drilled 3 holes(2 3/8 hole) above the airhorn's and noticed right away about 90% of the popping was gone and also seen 105mph on the trails at +5c(still pulling when I let off)I have opened the holes a little more and put frogzskin over them..but the snow is gone so I cant say if it is better again.
My issue is the clutching...whatever kit/homemade set up he has it engages way to high 4300/4400 and is very annoying...problem is I don't know what setup is in the sled to lower the engagement without screwing up the way it works...not interested in spending $600 cdn to just a lower engagement(and maybe less performance). Added a few pic...if anyone may know what springs(rate) and helix(angles) might be it would be great. Sled also has Dalton weigh
power commander.JPG
helix.JPG
helix 2.JPG
helix 3.JPG
kit.JPG
primary.JPG
primary2.JPG
power commander.JPG
helix.JPG
helix 2.JPG
helix 3.JPG
kit.JPG
primary2.JPG
primary.JPG
t's..not sure on weight as I never got in that far. Sled runs at about 8800/8900 on the top rpm..
 

If that is all you want to change, then you need a primary spring with less engagement, but the same rate. You could send that spring to Dalton if you can't measure its force, or if you don't know who's spring it is, then they could send you something more suitable.
 
I may have to send it to dalton and see what they can come up with.
 
Looks like a heel clicker gray primary spring
 
SB comfort clutch kit gives you smaller primary rollers and a softer spring. Engages at 28/2900, fantastic! No upper end change.
 
On my stock clutched sled, I installed a new Yamaha spring p/n
90501-586J0-00 to lower my engagement. On my second season with it, works awesome, makes reverse usable vs nerve-racking. $35 off ebay.

Coming from past experiences with Ski Doo, I learned they always talk about start/initial preload of the spring installed in the clutch and the finish force of the spring, and they quite frequently have a chart list of all oem and aftermarket springs options to help with tuning. It was really handy. For example, if you had a 120/280 spring it would be a start force of 120 pounds and finish of 280. If you want to drop the engagement rpms but retain the max rpm, pick a spring with less start force (90) and the same finish (280). This is just an example, I don't see spring forces mentioned often on here. There is a chart somewhere on here, but it's been a while since I came across it.

Anyways, that part number I gave has been successful for me for my stock sled. And cheap. But since you have aftermarket clutching, I can't promise it would work for you.

EDIT: here's a spring chart for future reference https://totallyamaha.com/snowmobiles/aaTECH/drivespecs/primary_springs.htm
 
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That looks like a heelclicker grey which is a very stiff spring. Heelclicker BLACK primary spring works fantastic and lowers engagement below 3K on Nytro with H/C weights. If you are running Dalton weights put in Dalton Red or Yamaha Pink-Orange-Pink.
 
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