project m7

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We teamed up this past season with a slew of partners to build a wild-child '06 Arctic Cat M7.

Here's a condensed report on Project M7, and how our mountain friends modified this 153 -inch LE model. A full report can be found at www.amsnow.com/sno/default.aspx?c=a&id=2483.

Bret Rasmussen, of Mountain Magic Sports, jump started the work in late January.

M7 begins overhaul
First, Rasmussen added Cat's yellow hyfax (Part No. 2604-296, MSRP: $33.90), front-shock protectors (Part No. 4639-136, MSRP: $39.95), kneepads (Part No. 4639-111, MSRP: $39.95) and black-chrome windshield (Part No. 4639-201, MSRP: $59.95). This first easy installation took only about an hour.

Next, he cut out the necessary patterns for SLP's Hot Air Elimination Kits (Part No. 32-530 and Part No. 32-531, MSRP: $84.95 each, $169.90 total), which were installed on the side panels. These screens allow proper under-hood heat management and ventilation. SLP has developed a new air intake system known as a High Flow Air Horn Intake Kit (Part No. 14-291, MSRP: $34.95) that allows the motor to induct fresh air with little obstruction.

In addition, SLP set us up with a set of its yellow-bottom, orange-saddle and orange-hoop Powder Pro skis (Part No. 35-335, MSRP: $220.70, Part No. 35-356, MSRP: $76.06 and Part No. 35-357, MSRP: $35.98 respectively). The ski package also included 6-inch 60-degree Aggressive Trail/Loose Snow Carbides (Part No. 35-123, MSRP: $149.90).

The cosmetic changes were easy and just the beginning of the transformation.

Getting serious
Next, Rasmussen tore the cylinders off the M7 so Starting Line Products could work on the M's mild trail-mannered porting - tweaking the power plant by porting its intake and exhaust ports. This Performance Edition Porting ($415), pumps the power to 155 horses with a broad usable power band.

Subsequently, Rasmussen reinstalled the cylinders before adding a set of SLP twin ceramic-coated pipes with silencer (Part No. 09-762CP, MSRP: $810). These pipes add 12 horsepower and 6 1/2 foot-pounds of torque at 8,100 rpm and provide a broad power band with incredible low-end and mid-range performance. The pipes also maintain low sound levels and reduce weight by 3 lbs.

Be aware though, the M7 is an EFI motor, so with twin pipes and porting, this motor requires a Boondocker EFI Control Box (Part No. 57-50, MSRP: $398) to provide proper fuel metering.

The box remaps the M7's electronic fuel injection for SLP's porting and pipes to keep the motor running in its optimal zone with the added mods. The box has an LCD screen with a five-button interface that allows the tuner to modify the motor's existing fuel map.

Dialing it in
Rasmussen relied on experience and SLP's baseline figures to dial in the motor's fuel needs.

Then it was clutch-time! AmSnow test rider and wrench man Kevin Allred hit the mountains with Rasmussen to test clutch configurations and tune the EFI's fuel map via the control box. Afterward, they decided they needed Exhaust Gas Temperature probes with a gauge.

Why? With 3-D ignition, pipes run hotter at mid-range than at full throttle. To verify lean or rich conditions at mid-throttle, and from this point to WOT (wide-open-throttle), Rasmussen looked for a gradual increase in pipe temp rather than a rapid spike. An EGT gauge reports this. Even though a motor is EFI, and has a control box, it still needs to be tuned.

SLP helped us out again and delivered a 2-inch by five-eighths dual channel EGT system with memory (Part No. 19-79, MSRP: $280). According to SLP, "This gauge uses Auto Scan Technology to automatically monitor both cylinders at the same time and register the hottest temperature of the two while recording the peak temperature of each cylinder in its memory." With probes inserted into the pipes, and the single-faced dial dual-pipe gauge installed, Rasmussen spent additional time adjusting the fuel map and zeroing in on the right clutching.

We highly recommend an exhaust gas temperature monitoring system when tuning an EFI motor (through a control box) that has a set of twin pipes, is breathing in large volumes of air and that is ported. Otherwise, you will spend double your hours trying to tune the engine.

Mountain Mod test
At our annual Mountain Mod ride, we tested our M7 setup. On day one, Rasmussen dialed out some fuel and oxygen at mid-range to keep the motor crisp for the day's high-humidity and heavy fog.

The next day was cold and clear. The mild-ported M7 motor snapped with life. We achieved our goal of building a project sled that an average mountain rider would want, not something so expensive that a normal consumer couldn't afford it.

There's more?
Yep! Fabcraft, makers of ultra lightweight sled parts, provided new rear axle wheels for our M7. These 8-inch wheels are made of durable new composite plastic and weigh a scant 8 ounces each. The upper idler wheels, which are 5 5/8- inches, weigh 4 ounces, not counting the bearings. These wheels provide a significant weight savings over stock wheels and are lighter than most aluminum wheels.

Composite plastic also does not hold ice like polished aluminum, where snow and ice will flash-freeze. Also, the wide windows on the Fabcraft axle wheels allow snow to pass through, preventing buildup.

Next, we installed light ultra-strong chromoly upper and lower A-arms from Spencer Suspension Products (SSP) in Gaines, Mich. Terry Spencer - creator and fabricator - is a master welder and metal man. Spencer, who has made parts for Team Arctic snocross, cross-country, ice-ovals and grand prix racers, supplied the front-end suspension parts.

His A-arms cut 7 lbs. off the stock arms. For mountain guys, reduced unsprung weight is paramount, and SSP gave us that - strength with minimal weight. The chromoly arms are tough even though the walls are thinner than the stock steel A-arms. However, you do not want A-arms that are overly strong or they will rip out the bulkhead if you smack a rock or a tree.

The final add-on, a Boondocker Liquid Nitrous System, came after the snow dissipated, but it is installed and ready for our first powder rides this coming season. The system adds about 30 hp at peak rpm, so we should get 180 to 185 hp.

More info: Cat, www.arcticcat.com; Starting Line Products, 208-529-0244, www.startinglineproducts.com; Fabcraft, 406-777-1200, www.fabcraft.com; Spencer Suspension Products, 810-444-0061; Boondockers, 877-522-7805, www.boondockers.com; Mountain Magic Sports, 208-852-0400.