His and Hers-- Polaris 120 Mountain Sled Build

[H1Pilot]

His and Hers-- Polaris 120 Mountain Sled Builds--Tons of PICS

I hope this information is helpful for anyone else trying to build a capable mountain sled with a long track for your Kid(s).

I am building 2 sled that are nearly identical, just different colors.

2006 Polaris 120...Red/Blue
2008 Polaris 120...Pink

Motor Upgrade: Robin EH17 w/stage 2 kit from RecMotor. 8+ HP
Dominator Clutch
Extrovert Drivers
Custom 98" track (68" is stock)
Custom rails/suspension
Custom seat
Custom steering post/riser/bars

I'll start with the handle bar upgrade. The newer model polaris 120's have an adjustable pivot on the bars that is very handy. I cut the stock bars off, saving the pivot mount. I welded a 4" long piece of 7/8" tube in place of the handlebars and attached the 4" tall aluminum handle bar risers.

I used 7/8" tubing for the handle bars. They are about 24" wide and have the same rake as a KTM 50 dirtbike. I added heated hand grips and a bicycle type 2-finger brake handle.

 

[H1Pilot]

Mini Mountain Sled Engine Upgrade

I installed a Robin EH17 w/stage 2 kit from RecMotor in both sleds. The EH17 is 6+ HP stock, and the stage 2 kit puts it well over 8. In comparison, the stock 120 motor has no HP

The new motor bolts right in, but is slightly taller than the OEM motor. RecMotor supplies shims to raise the steering post to clear the motor. I was unable to clear the motor on the boys sled with 1/2" of shims, so I re-bent the steering post instead. The shims worked on the pink sled...

I had to transfer a few items over from my old motor to the new motor. A couple of linkage brackets and the choke. Everything connected nicely. I had to change one electrical connector end, as it did not match the new motor(both round, just different diameter).

I used a hole saw to create a larger opening in the belly pan for the exhaust.

 

[H1Pilot]

Slide Rails for Mini Mountain Sleds

I picked up a pair of rails from a Polaris with the Xtra 10 skid. I used my Plasma cutter to trim the extra material off the top side of the rails and fabricated my own mounting points for the front torque arm. I am using the same tunnel mounting holes. My new rails are pushed down 1" vs the OEM setup. The approach angle is greatly reduced with the new rails as well.

I cut the tail end off the new rails after several mock-ups. I then cut the stock rails off and will weld them to the new rails. I had to do this because the stock axle/wheel/tension adjuster is different than a full size sled.

At this point, the rear skid is assembled and set in place. I need to weld it together and add the rear shock. I am undecided if I will ad a rear torque arm yet.

The track measures about 98". It is basically 1 1/2 stock tracks molded together. I will fab the tunnel extension once the track is in place.

After all the work I did on the rails, I needed to change it. The front mounting plate on the rail is too far forward so the rails rock forward when weight is applied to the sled. I needed to move the rail mounting location back to just before the point where the rails start to bend upward. Too keep the same geometry, I extended the front torque arm at it's current trajectory and did a bunch of scratch paper math to come up with the solution...so far so good, but I will wait till I test it before I build the second set.

 

[Racer220]

Great info on the builds. Keep it coming. Will be nice to see how they perform compared to the stock setup. I just picked one up with a 5hp setup to get the kids started this year. Ideas like this are awesome to bridge the gap between the 120 phase and a full size sled.

racer

 

[grumpyoldbastard]

That's awesome! I have been asking Grumpy how that has been coming along.Keep up the good work and let us know how it works. By the way this is Grumpy's brother.

 

[H1Pilot]

Rear Shock/spring

I am adding a shock/spring to tame the rear of the skid. There has been considerable write up on adding a rear shock to dampen the pogo action of the stock suspension, but my belief is that I will need a the additional spring due to the leverage of the longer rails...time will tell.

The shock is a Honda crf50 replacement and measures about 10.5" eye to eye. It has the 140#-170# spring on it with adjustable spring preload and dampening. $130 each.

I completed the installation of the rear shock. I made aluminum shock mounts for the upper and welded them to the upper carrier. My concern was that the carrier shaft would slip or rotate when shock pressure was applied. After installation, that doesn't seem to be a problem. I built the mounting tabs long enough so I can run a threaded rod from one side of the tunnel to the other and through the shock eye if I have to, to keep the carrier shaft from rotating.

I used 10mm threaded rod for the bottom shock mount and sleeved it with 1/2" square tubing. They are basically a crush sleeve on each side of the shock. It is only a 5" span between the rails, so there is no deflection of the rod when pressure is applied and the square sleeves strengthen it even more.

 

[sammy418]

sleds

were did you get the track done

 

[H1Pilot]

RecMotor had the tracks built for us. I took 2, and my friend took one a little longer in length.

 

[H1Pilot]

Hi-Rise seat

I added 3" of foam to the top of the Pink Flamer sled. I used black Gripper vinyl and pink canvas. I have a little more fitting to do to get the wrinkles out.

Grandma came over for Thanksgiving, so I put her to work fitting the seats a bit better than first effort. They turned out very nice and raise the seat 3" over stock.

 

[MARV1]

Nice, wish I had the time and extra cash to do something like this... By the way, I am in need of a stock track! Price shipped to zip 99620, usps priority mail. Thanks.

 

[H1Pilot]

I don't have a track for sale.

 

[H1Pilot]

Steering post mod #2

I originally started with a 2000 Polaris 120 with fixed handlebars. Here are the pics of how I modified them to accept a pivot/riser with new handle bars.

I moved this steering post and bars to the pink sled and sold the 2000 sled.

I used a powermadd pivot with a 2" riser that had been rolling around my garage for several years. I built the handle bars out of 7/8" tube and installed heated grips and handguards. I think a 4" riser will work better for my 8 year old daughter, but will wait till I get the sled on the ground to check how the bars fit her both standing and sitting.

 

[H1Pilot]

Tunnel Extensions

I don't have a bender for flat stock, so I drew a diagram for my local metal dealer. They bent the tunnel extension for $45 which included the aluminum...not bad. The extension is 10" long with a 5 degree upward tilt. This angle matches the running board angle.

I used wax paper to sketch the side supports. I like the side supports found on the new Polaris sleds and VanAmburg tunnel extensions. I am using 14 guage (I think) aluminum for the sides and a 3/4" round alum. tube for the bumper. I will likely have the sides and bumper painted...maybe.

 

[Scott]

That's a great project. We are at the stage where my 8yr old is getting big for his 120.
Wondering if a 340 or a 550 fan is the next best move.

 

[H1Pilot]

I am looking forward to building a 340 to 550 sled. The question is when. Any kid can ride a full size sled down the trail, but mountain riding is another matter. I have a 6 year old boy and 8 year old girl. They both ride and race dirt bikes, so a stock 120 pretty much sucks. I bought an 87 skidoo 377 last year, and neither one of them wanted to ride it because it was too big (really?) and too fast. That is why I decided to build off of the 120 chasis. It is small and light enough for them to actually manuever...and after all of my modifications, it will still fit them until they are 9 or 10.

I will probably start working on a 05 or newer skidoo 380 Rev short track next year for my daughter. It will be interesting to see if it can be thrown around by a 10 year old...time will tell.

 

[Scott]

When we bought our 120, it had some good engine and clutching already done to it.

Jackshaft was flipped and comet clutch was installed.
Head was milled.
Pipe was added.

It's pretty snappy.

It ran well on the powdery road road while following in my ungroomed track with 2' of snow with no base a couple weeks ago.
He went 13 miles and averaged about 16 mph the whole time. He was hitting up to 18 pretty easily.

The moment he got outside of my ski tracks, he got stuck though. LOL

He did talk about how the shocks were bouncing him all around and I noticed he was getting pogo'd around. He kept putting his feet down for balance when he got out on the edge of the track. He got tippy pretty easily.

 

[H1Pilot]

Have you looked at the shock-it kit? I am adding a rear shock to control the pogo action, but I have no actual experience with it...just what I have read. I decided to use a shock w/spring due to the additional leverage created by the longer rails. If I had a stock track length, I would just ad the shock without the spring.

You said the sled is tippy...Is it the ski stance, narrow skis, or rider balance. So far, I have decided not to widen the ski stance. I have bought C&A pro skis for them which are longer and wider. I hope this will keep the front end from diving in the powder.

 

[grumpyoldbastard]

Looking good H1. I keep checking back to see the updates. Those are going to be saaaweet! I'm glad that you are doing all the figuring, so when i'm ready to do it I can just give you a call, buddy o pal. Ha Ha. Can't wait to see them in person. Grumpy's Brother

 

[H1Pilot]

I'm going to bring at least one of them over to your brothers house on Friday. Just so you know...I will build these for my kids, but you could never afford to pay me to build one.

 

[Scott]

Will you share your costs with us?