08 nytro 121" to 153"

[blaketown08]

2008 fx nytro 121", I have purchased a 153" skid and track. Installing it into my 121"
gonna get welder to make up the tunnel extension.
I have measured the drop brackets on a 153" and it looks like the holes are at 4 inches..
the Drivers will need to be changed to 3.0" pitch ( not sure best tooth option - 7-8-9- )
the front mount for the skid looks like it will be moved back not sure on exact measurement.
what gearing will i need to make this?
stock is 22/39 what is mtx gearing?
will a 2 1/4 track fit in the 121" will the heat exchanger need to be moved?

what else should I need to know?

 

[Confused?]

I have heard if go from a fx to mtx with any paddles over 2in you have to get a mtx Speedo. I'm not sure if this entirely correct though.

 

[pro116]

20-40 is mtx gearing.

 

[blaketown08]

nytro 121" to 153"

yea i have heard about the speedo, but not too worried about the speed. dont look at that much anyway.

timber sled mtx front end installed, with pilot skis from brp.

hauck header and exhaust. KandN air filter.

power commander.

i guess i will find out about the 2" track lug.
may need to move the heat exchanger an inch or so.

 

[Off Trail Mike]

Blaketown:

Couple of considerations:
1. Your 2.25" track will fit with the exchanger in stock position with 7 tooth 3" pitch drivers (which are the stock MTX size)
2. Since you ply the mountians on the great rock of NFLD, then you will have to clutch for sea level, so be careful when asking about clutch setup here on TY. The MTX comes from the factory geared for high altitude, and if you operated on at/near sea level, it'll overrev all the time. To solve this my dealer installed a "Sea Level Clutch Kit" on my MTX. It works great and was part of the purchase deal. Here's what I know is in the "sea level kit"

Gearing: 22/40
Requres new chain:
Primary Spring: Blue Brown Blue,
Secondary Spring: White
Stock MTX secondary helix

The only thing I am not sure about is the primary weights, it looks like 17.2 inner and 13.3 in the outer two rivets. Might be the stock MTX weights, but can't confirm. I'll ask my dealer to see if he can help out on this one.

It might be easier to give Ulmer a call. With all your mods, you might need more than the stock setup. He can set your sled up with a clutch kit and a PC5 program to work with K&N/Hauck, and if you are lucky, he might be able to keep your stock 121 gearing!

Have fun with the build.
OTM

 

[Dimebag]

21/39 = 0.54

22/40 = 0.55

Not much of a difference.

 

[blaketown08]

Hey Off Trail Mike,

Thanks for the helpful input. I will look more into these considerations, the yamaha dealer here in corner brook didnt know what drivers were and told me to call bender... but I usually deal with ulmer and huack.

How much of a difference would i see in stock 121 gearing compared to 153 mtx??
would it be wise to drop only two teeth?

Thanks so much for reminding me about the clutch, it actually slipped my mind. I will take mine apart and check it out..
would like to see what people think about the clutching and what they prefer when riding " sea level "
and back country style riding...

I will be ordering anti ratchet drivers, heard many people say 8 tooth 3.0 pitch
also hear some people trimming the slide rails??? not sure what this does.

Will heat be an issue... I have never ran hot with 121", I've ridden hard in 12 degree celcius weather, never a problem..

Looking into Better boards...... they seem to be a little weak. any thoughts????

thanks so much.

 

[Off Trail Mike]

Blaketown:

As Dimebag said, don't worry too much about gearing as the stock RTX/XTX pretty much works for the MTX "Sea Level" clutching anyway. Talk to Ulmer though, he can make your life easy. The clutching is closer to the RTX/XTX, but its designed to pull harder (more revs) down low and shift more slowly to keep power up. Down side of my setup is I'd be lucky if my MTX gets passed 85mph on top end....not that I care anymore, and besides, the only thing that happens to a 2.25 beyond that speed is you throw alot of lugs and wreck your track.

On drivers, you are pretty much stuck with a 7 tooth driver because of cooler clearance. I haven't heard of anyone running an 8 x 3 with a 2.25 on a Nytro, but might be wrong on that.

Trimming rails??? Don't know... I run a Cat skid.

On running boards. Go straight to the SPG Air Frames. Expensive...yes, but bulletproof and totally functional. Say goodbye to ice buidup. Love them.

Heat? Probably not. If you were Turbo'd I'd say yes. The tunnel cooler is easy to install if necessary. Ice scratchers are a must to protect hyfax and control heat. I'd worry about them first.

One other thing I saw on your first post was skid positioning. The front holes for the MTX are already on your tunnel. If you look down and back from your current mounting location, you should see these punched holes on the tunnel. You are going to have to modify the front reinforcing brackets to get the MTX skid to fit those holes. Also, on drop brackets, it might be easier to fabricate your own out of aluminum. The Yami ones are pricy and heavy.

Got to get to the Rock. Everything I've heard about the west coast is epic...

OTM

 

[blaketown08]

Looking into those SPG air frames. they look awesome.

I had been thinking about making my own drop brackets, i went to yamaha and measured the mtx bracket.
May drop mine an extra inch.

Everything should work perfect...
the only reason behind the 7 to 8 tooth drives is that it helps the track flow easier, smaller cog the track needs to make a sharper bend.

I would like to flip my skid rails so that the track tension adjustment is on the outside of the rails,
make life a little easier...

Anti stab or not to anti stab?????


The west coast of the island is awesome sledding. something for everyone. steep hills, great back country riding...
worth checking out....

thanks OTM

 

[Dimebag]

 

[blaketown08]

thanks dimebag..

the rear tunnel drop bracket hole is already in place, should be able to line up the front suspension holes
fairly easy.
will post pics soon.......

thanks for all the help guys...

 

[blaketown08]

waiting on a reply from ulmer, about clutching.... hope he has something great...

 

[xcalhed]

Bump??

 

[edge_232]

I'm late to the game on this one but I'm running the 7t 3 pitch a vids on my 153 & love them plus my PC 2.6 clears the front heat exchanger. I'm not sure if the mtx front heat exchanger is different from the shorties but I don't think they are. If you need help on the rear of front mounts let me know.

 

[edge_232]

Almost forgot always anti stab! The time you don't will be the last. For $100 it's an brainer.