Musclesleds of the traditional state are a bygone era. The triple-triple Thundercats, Storms, Mach Zs and SRXs were some of the hottest iron of the 1990s. Those sleds went fast across a lake, but they weren’t so great on the trail.
Fortunately for sledders who want more torque and horsepower without the school bus ride and handling characteristics, a new breed of big-bore, twin-cylinder snowmobiles has replaced those beasts from the decade that made it cool to own a pink-and-purple sled.
We ran a black F1000 Sno Pro last season and we wanted to see whether a few simple changes would help the sled pick up speed.
We called up D&D Power Sports tuner/drag racer Glenn Hall to help dial it in and drive the machine for our Stalker radar gun. After all, Hall won the Stock 1000 class at Haydays a year ago. The Wisconsin native has won a handful of other classes at Haydays, too.
Hall brought us to a flat and smooth drag strip near Gordon, Wisconsin, for quarter-mile runs. He also brought a few D&D parts to bolt on. We did the work in the field on April 5 as the spring sun was climbing high in the sky.
Even though air temperatures were around 20 degrees F, the snow started out tacky and got worse as the day wore on. That kept our speeds lower than we’d hoped. Despite that, we learned where a precious few miles per hour can be gained.
1. 9:40 a.m.
Stock
The sled was stock other than 168 Fast-Trac studs screwed in the 15- by 128- by 1-inch track. The fuel tank was at 7/8 of its capacity and the odometer showed 725 miles. The drive belt was on the loose end of the specification, but the clutch sheaves were relatively clean and the track was loose.
Observed speed: 104.7 mph
Conclusion: Our best baseline speed was set on our first run with a cold engine. The next two stock runs were progressively slower.
2. 9:55 a.m.
Installed single-runner
wear bars; $65
Theory: One bar per ski reduces drag against the snow compared to the stock dual runners.
Observed speed: 101.95 mph
Conclusion: Single runner wear bars didn’t have a significant effect on speed, but better snow conditions might have proved otherwise.
3. 10:15 a.m.
Reduced Fox FLOAT
pressure from 50 to 25 psi
Theory: Drag racers always lower their sleds, why can’t we? This helps the machine cut through the air, but the main thing is to help the sled launch without doing a trackstand. It also might reduce roll resistance because the track approach angle is less abrupt.
Observed speed: 101.31 mph
Conclusion: This half-hearted effort wasn’t worth the 3 minutes we put into it.
4. 10:55 a.m.
Installed D&D Shift Assist bearing in secondary clutch; $44.95
Theory: The bearing lets the spring rotate as it’s compressed and allows the clutch to upshift freely.
Observed speed: 102.82 mph
Conclusion: When compared to the previous runs, our acceleration graphs showed quicker acceleration through the mid-range. The bearing would likely cause quicker backshifts when trail riding, too.
5. 12:15 p.m.
Installed 14-inch wide track with 168 Fast-Trac studs; $554.95 (track)
Theory: A narrow track has less rotating weight and has less contact with the ground, which equates to less rolling friction.
Observed speed: 104.94 mph
Conclusion: The narrower track helped us pick up more than 2 mph on top. Warmer air and stickier snow was working against us.
6. 12:40 p.m.
Adjusted skidframe’s
coupler blocks to lowest position
Theory: This improves weight transfer and helps the sled launch off the line quicker.
Observed speed: 105.73 mph
Conclusion: We picked up close to another mile per hour at the 1/4-mile mark. The graph showed faster acceleration, too.
7. 1:00 p.m.
Scuffed clutch sheaves and drive belt side walls with emery cloth
Theory: This helps the clutch and belt get better traction to improve performance and reduces power-robbing heat.
Observed speed: 102.85 mph
Conclusion: Seat-of-the-pants impression from Glenn was that the clutching felt more aggressive. Engine held at 7200 rpm. The sled didn’t hook up well, but better traction would have made it accelerate harder.
8. 1:20 p.m.
Installed new belt, scuffed it before
installation to remove mold release residue; $150
Theory: We were curious to see whether this easy change would make a difference. It’s important to clean new belts before installation because mold release used in manufacturing will cause the belt to slip.
Observed speed: 101.74 mph
Conclusion: Perhaps once the belt is broken-in it would start to show improved performance.
9. 2:00 p.m.
Installed D&D Y-pipe and four BullsEye air intakes; $189.95 (Y-pipe), $42.95 (BullsEyes)
Theory: The better an engine breathes, the more horsepower it will produce. BullsEyes allow more air into the engine and the Y-pipe lets the exhaust gasses get out quicker.
Observed speed: 105.9 mph
Conclusion: Better flow also helped drop its 0-60 mph time to 3.38 seconds.
10. 2:35 p.m.
Installed D&D 48-44-40 helix in the secondary clutch; $86
Theory: To put more load against the engine and not waste the horsepower it was producing. Could’ve added more flyweight instead, but we didn’t have weights.
Observed speed: 107.24 mph and 7400 rpm at wide-open throttle
Conclusion: A 1.34 mph gain is huge! How much power was missed by the pulleys before we made the clutching change?
11. 3:45
Installed 68-/52-tooth gearset from Black Dia- mond Extreme Engineer- ing; $199.95
Theory: This was the tallest gearset available; the stock set was 66/54. Our goal was to get maximum top-end speed.
Observed speed: 107.72 mph
Conclusion: Even though we saw a gain, conditions weren’t right for this gearing combination. Sticky snow under mid-afternoon sun put too much load on the chassis. A long, hard-packed run or ice chute is where a 68/52 setup would show a significant gain. Curiously, the 0-60 mph time was the day’s best at 3.3 seconds.
The End Of The Day
Though we didn’t see big gains in top-end speed, we proved that a narrow track is faster and simple skidframe adjustments cause better acceleration.
Variables with the dragstrip (snow condition), air (temperature, humidity) and snowmobile (engine temperature) worked against us and made it difficult to show quantifiable setup improvements.
If we had worked in a vacuum without those variables, we’re sure we would’ve turned quicker trips down the runway.
