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Getting A Little More From The MC 900

Published online: Aug 15, 2003 Feature
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Washington state's Lyle Jones really enjoyed riding his 2003 1/2 Mountain Cat 900-but he wanted more.
So he went to work-adding, tweaking, changing and testing. The result? A sled which Jones describes as "It will outdo my highly modified T-Cat any day. I am not disappointed."
Jones and his family and friends do a fair amount of riding in the Cle Elum area in Washington. He explained his family has 16 sleds (all Arctic Cats) and three of them are Mountain Cat 900 1Ms with 159-inch tracks. We asked him what kind of riding his family does, just to give us an idea why he wanted more from his MC 900s.
"Most of my riding is off trail," he said. "We do mostly point and shoot, boondocking and highmarking. We have pioneered out ways to go between our favorite riding places without trailering the sleds between them. We were not able to do this without the newer sleds. The older sleds were not agile enough to negotiate these high mountain passes."
 He continued, "If you look on a map of the Lake
Cle Elum area, we are able to go between French Cabin Creek bowl, Knots Creek bowl, Red Mountain bowl and Stave Creek bowl without going down to the main highway. We can do this mostly by going above the tree line and traveling the high ridges along big snow drifts. We do have to go boondocking in some areas through large trees that have been left because the loggers cannot get to them, except with helicopters. But this is expensive for the loggers and there's not enough timber in these areas to make it profitable for them. Some of the high alpine lakes we visit are Thorp Lake and Little Joe Lake."
So what has Jones done to his MC 900s to make it possible for this kind of cross country travel? Not too much actually. "This is the first snowmobile that I have had to do very little to to get it to perform the way I like right out of the box," he said. "The only out of pocket expense was the gearing and that was about $100. All other changes I made to it were adjustments to the carburetion, clutching and suspension. Most of the changes can be done without any cost for parts, only time and some mechanical ability."
Here's what Jones did to his 2003 1/2 Mountain Cat 900 with a 159-inch track.
1. Gut the air box and be sure the four 1-inch holes are cut in the back of the box and covered with screen.
2. Carburetor jetting: 350 main jets (3,000 to 8,000 feet elevation) with the needle c-clip in the third notch, any way you look at it in the middle notch. At 9,000-10,000 feet in elevation, the guys are using 330 mains.
3. Put heavy duty limiter straps (the ones from the factory break) in the suspension and adjust, for your style of riding, so the skis can be raised or lowered with the throttle when highmarking. I like to highmark with the skis raised, but sometimes I need the skis for steering around objects like rocks, trees, etc.
4. Gearing: 20:46 gears with 74 pitch chain, 15mm wide top gear and 13mm wide lower gear. It seems to run easier as the chain can align itself on the lower gear. I also put some extreme pressure chassis grease (has moly in it) in the box to lower friction along with the regular gear lube-usually about 5-6 squirts from the grease gun will do the trick. Some of the guys are using a 19-tooth upper gear, but we have experienced gear failure in about 300 miles. The teeth break off as well as excessive tooth wear is experienced. Arctic has been replacing the gears, but I do not like failure when I'm riding. I hate to be towed back. Costs: 46 tooth gear, 13mm wide-$61; upper gear 20 tooth, 15mm wide-$25; chain 15mm wide, 74 pitch-$50
5. Clutching: yellow/green spring in primary drive clutch with 70.5 gm weights, driven clutch 55/53 helix. Some of the guys are using a straight 55 helix at higher elevations, with red/white spring in the tight notch. When I hit the throttle wide open, the rpm goes to about 8,000 and then settles down at 7,200.
6. Skis: I don't personally like the parabolic skis. They throw snow in your face and do not turn as good as Simmons Flexi Ski. The straight Arctic skis off the ZR are even better than the parabolic. Who needs skis anyway when highmarking?
7. Springs: adjust for your riding style and weight. Every one of our guys and gals adjust them different for their particular riding style and weight. We weigh from 160 to 260 pounds. 
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If anyone is interested in more details on what Jones has done to his sleds, you can e-mail him at:
ljones0281@hotmail.com.