PROJECT ATV: Polaris Scrambler 850
Project Scrambler 850
We have always liked the Polaris Scrambler line of machines. These rack-less sport 4x4s are super fun to ride and go virtually anywhere. The original Scrambler had a 400cc two- stroke engine and straight-axle rear suspension. It was later outfitted with a 500cc four-stroke, then completely changed into what we have today. This Scrambler model in the Polaris lineup is basically a rebodied Sportsman 850 using fully independent suspension with compression- adjustable Fox shocks. A base model with non-adjustable shocks and no power steering is also available.
The Dirt Wheels crew actually built the first Scrambler using this chassis back in 2010. If you search “2010 Polaris Sportsman 550,” you will see a small video featuring that machine. The project happened sort of by accident after we rolled the Sportsman down a big hill and destroyed the racks and instrument pod. There is a video of that incident out there too. So, we removed the racks, installed Ogio rack bags and a small storage box up front, along with a Warn winch, handlebars, tires and more. It was awesome.
This month’s project based off of the 2013 Scrambler 850 is a bit different. First off, it started with a machine that was in perfect condition. We had just finished comparing it to the Can-Am Renegade. You can read that article in our June 2013 issue. This time we wanted to try a few different ideas with the Scrambler. Our main goal for this build was to make the machine bulletproof. We planned several big rides with it and plan on racking up some miles.
No matter if we are testing a machine, bolt-on parts or riding gear, flat tires come into our lives on a regular basis. DWT is the first major tire manufacturer actively trying to eliminate them. Their Moapabranded tire is the first 12-ply utility product available to the general public. The military has been using a version of this tire for well over a year. DWT does have sport quad tire sizes in the works as well.
The smallest Moapa size DWT had available for us to test were 28×10-14s, so this moved our build in the
direction of a monster quad. It’s not like this concept is anything new. Guys down south have been building big mud quads for years, and other folks across the county are starting to build these monsters for rock crawling and such.
We wrapped the Moapas around a set of DWT’s Rok’N Lock beadlock wheels. The 4/4 offset made the tires stick out 3 inches wider per side. The package gave the Scrambler a very aggressive look. The tires are heavy, and you probably wouldn’t want to run them on any machine with less than 500cc. They do put a big load on the CVT belt too, so the use of low gear comes into play more than normal. Power steering is highly recommended as well. The cost of Moapa is a bit heavy too, at $228 per tire. However, that’s a small price to pay to never have to worry about being stranded by a flat tire. These tires are so tough, you can hardly tell if you were riding on a punctured tire. Traction was awesome as well. They clawed through the loose dirt and tacky soil well. Mud clean-out was fair, and they rolled very smoothly on hardpack. For normal high-speed riding, we would not choose the 10×28 sizing by choice, but they did wonders for stability and ground clearance. We plan on putting more time on these 12-ply Moapas under our RZR XP 900 in the near future.
To stay on top of any CVT issues that may come up, we installed a complete $1500 clutch package from STM Powersports. The package contains a very adjustable primary clutch, secondary clutch and helix. Also included with the kit was a selection of weights and adjustment pins for tuning the system. We tried the STM products with the massive 28-inch DWT tires and
with the 26-inch stockers. The STM product is a work of art.
The CNC-machined pieces look like a prize-winning sculpture that was built by a high-tech robot. Its details are so cool-looking, it’s a shame it has to be hidden by the CVT cover. A clutch package this sophisticated are generally reserved for highly modified engines. In our case, we may build the engine in the future, but for now, we are taking advantage of the increase in top speed it gives the Scrambler.
With the stock tires, the STM clutch still engages smoothly at low rpm. However, when you stab the throttle, the revs jump up quickly, and the big beast shoots forward; you can tell the clutch is running in the meat of the powerband. On one fast dirt road, we were able to hit 85 mph according to the stock speedo. The most we could ever get in stock trim was 72 mph.
Using the heavier, 12-ply tires, our stock-tire mph dropped to 70 mph. And after we installed the STM clutch package, we were able to pass 75 mph, and on a quad this big, that’s plenty fast. Installation was pretty straightforward, thanks to STM’s own tutorial, which you can find on YouTube. So far we haven’t had to make any adjustments. STM recommends using the stock Polaris belt with their system. We suggest starting with a new belt when you are doing any kind of major clutch upgrade.
RIDER SUSPENSION AND SHOCK SETTINGS
The stock Fox shocks are holding up well on this animal. Even after we raced and won the 4×4 class at the whooped-out Sand Hollow Utah WORCS race, the shocks didn’t leak or weren’t soft. We did, however, add a half inch of preload in the rear of the machine to make it a little more stable in the turns and to level it out some. The compression dials, front and rear, are two clicks from full hard.
To give the rider a bit more suspension action and comfort, we installed a set of $359 Fasst Co. Flexx handlebars on this machine, just as we did on our project 550 Sportsman a few years back. This time around, we wanted to keep the stock instrument pod. To do this and mount the handlebars, we did a little trimming of the pod and mount- ed the bars to a set of 2-inch-tall $87 Rox risers. The riser clamped right into the stock clamp and the Flexx bars to the risers. We went with a 19-degree swept-back quad bend, which was perfect for this build. The great thing about the Fasst bars is that there is more than enough room for large light switches and control perches. On the downside, we could not use the cross-bar pad. Fasst Co. does sell dash mounts if you wanted to use an after- market speedo and get rid of the big pod altogether. The Flexx handlebars were superb when we torture-tested this machine through the rocks. They absorbed every bit of pounding the shocks did not. To match our black- and-red color scheme, we installed Torc 1 Enduro hand grips for another $13. These grips have a small waffle and a slightly fatter-cushioned profile than stock. Every pair comes with a small tube of grip glue, which is a plus.
Another suspension component we like on this machine is its “hump” seat. Right behind where the rider normally sits, Polaris added a small 1-inch-tall hump in the foam, and they sewed the cover around it to match. It works great for drag racing or hill climbing, so the rider knows exactly where he is positioned. The added comfort of the extra foam is just a bonus.
What we didn’t like about this machine was the forward-facing points on the rear rack. During that WORCS race, the first bump we hit, those points brushed right into our rider’s backside. It wasn’t painful, but it was just a reminder that they were back there. For this project, we removed the rack altogether. We would like to add a small storage box or bag in its place in the near future.
Up front, we installed a $199, 6-inch- wide Biltrite LED light bar directly to the front storage platform. We tested this light in last month’s issue and it was mounted on a Honda Rincon. It’s super bright, uses little energy and installs in minutes. It gives a wide path of light from zero to about 50 yards in front of the quad. We ended up drilling two holes in the flat plastic piece on the front cargo area to mount it. The battery is right under- neath this thick plastic plate, so wiring it up was a snap. We are get- ting a ton of use out of this small light bar while riding during those hot summer nights.
This project build turned out great. We learned that the Scrambler is capable of much higher speeds than stock. In fact, with the use of a STM Powersports clutch package, we think it would have no problem keeping up with a Renegade 1000. We learned that the bodywork can accept up to a 28-inch-tall tire without a lift kit. With only minor trimming, we are confident you could stuff 30-inchers under there. The STM clutch would help here as well.
The 12-ply DWT Moapa tires are not only strong, they offer traction abilities we didn’t even expect. We did run them without air too, and on this 700- plus-pound machine, we could hardly notice the difference. Our plan is to stick this tire-and-wheel package on a UTV next and to complete testing on the tire for a future issue. For this machine we would like to go back to a narrower offset wheel and a slightly skinnier tire. With a 4/4 offset in the DWT wheels, the front pushed a little in tight turns and was a bit grabby on hill-climbs. No matter what, we will stick to DWT products for sure.