151" RX1 susspension Vs. MPI upgrade in my 98 Venture

Feeze

Feeze

Member
Joined
Jan 3, 2005
Messages
52
Age
56
Location
Saskatchewan, Canada
I purchased this sled back in 99 and have "modded" it into a Mountain Max.

It currently has the stock 136" suspension in it & I am wondering if I am better off to put a 151" RX1 suspension or do the "upgrade" from Mountain Performance.
 
Dump them both and go with a RMK Xtra lite skid. Easy to install
and relitivley cheap. They are 22 lbs lighter than the 141 proaction skid
and transfer tons better.

A couple I have done:
156"
IMG_0347.jpg

156"
IMG_0761Medium.jpg

144"
IMG_0771Medium.jpg
 
Hammer what size of Polaris skid do you use for a 151" track? A 151" skid or a 144" skid? Is it difficult to install? Are the shafts the same width as the the Yamaha tunnel? How did you figure out where to mount the shafts on the Yamaha? Any info you whould share is greatly appreciated.
 
For a 151, either a 136 or 144 will work. I used old style hartman
rail extensions on that Viper and the 156 MM. I used the stock
Yami axle and set the rail extensions on top of the lip on the rail.
If you went with a 144 track, you can use a 136 skid with no extensions.
(see link for more info) 3rd photo. That is a 144 track, 136 skid, no exstensions and no tunnel extension.

I have never trimmed the shafts but the rear shaft on stock drop brackets
are short and you have to add spacers.

The first one I did was in the Viper with a MPI tunnel. I took the measurments
from the RMK in relationship to the drive shaft. I transfered those numbers over and found the front is in the same spot but the rear is about 3/8" to far
forward. You can either move you existing drop brackets forward 3/8" or make
new ones as I did.

It's a simple install, can be done in an afternoon if... ;)

More info.
 
Cat 1M skids work well also. I have a 136" in my Viper and really like it. Saves approx 20 pounds and better weight transfer/ride.
Most of the RX guys around here are ditching they're HEAVY stock 151 skids and installing Cat skids.
There has been a fair amount of discussion about it over on the 4 stroke forums.
 
Hey Mtnviper,

Would you have any pics you can post or send to my email?

Would be much appreciated!

How did you know where to mount it? What are the mods required?

Thx
Feeze ;)!
 
Cat M7 skids are also popular on RX-1s, would probably work fine on a MM as well. You might check on ebay, I just bought one yesterday for $400, it's the one with the Fox shocks and Ti springs. RVSports.com also has one, same price. I'm planning on an RX-1 for next year and will probably get one late this season if I find a deal, then start modding. I currently have a near stock MM, and yeah, the suspension is lacking.
 
Feeze

For mounting locations, I measured off of a buddies 03 mountain Cat. For the front arm, make your measurements from the center point of the drive axle, and down from inside of the tunnel. For the rear, I made a large caliper tool with a point on each end. Then just put one point on the front arm mount bolt, and other on the rear arm mount, measure the distance and there you have it! The tool also works for scribing locating marks on the inside of the tunnel for drilling the mounting point holes.
Most newer Cats come with 10 tooth drivers, so you'll need to mount front arm a little further back and down more, if using 8 tooth drivers, (9 tooth's will be close enough with the Cat 10 tooth spec. This is to compensate for the different diameter drivers.
The Cat tunnel is 3/16" wider then a Yamaha proaction tunnel. So I just removed 3/32 off the outsides of the front arm. Very easy to do with a stationary belt/disc sander. For the rear there is enough flex at the rear of the tunnel, the rear arm will slide right in.
Since your looking at 151 skids, you'll be using drop brackets instead of mounting the rear arm in the tunnel itself, like I did for the 136" skid.

Pics of the blue skid are newer, after I pulled the Cat skid back out to convert to a 16 wide track, powder coated it blue, and an off-set axle set up for larger rear wheels.
 
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