and Tech Section

Change a Belt in Under a Minute

Dyno Testing

Belts & Clutch Tuning


Bleeding Your Snowmobile Engine Oiler

Suspension Tear Down

Secondary Clutch and Wheel Bearing Service

Track Removal

Dyno Testing

 I recommend dyno testing your sled to almost anyone. People like me that put on pipes and oversized carbs, it is the only way to do it.

Anytime you modify a two cycle engine, it changes where in the rpm range it makes the most power, how it needs to be jetted, and things like ignition timing. The only right way to set this up correctly is on a dyno.

The first step in dyno testing is the basic tune up. The obvious stuff like fresh plugs, setting the choke cables, synchronizing the carb slides, and approximate jetting is installed.

Holes are drilled in the pipes a critical predetermined distance from the port, and exhaust gas temperature probes are installed. The clutch is removed from the engine, and a hydraulic pump placed onto the crank. Depending on the dyno and operator, a variety of other sensors are hooked up, such as fuel flow and intake temp.

The end result is an engine that is completley monitored by a graphing computer. Time to make noise. After warming up the engine, it is revved with varying amounts of pressure applied to the hydraulic pump to simulate the load of the clutches. Feul consumption and especially exhaust gas temps help guide you to proper jetting.

Once jetted, the ignition timing is set, and the test repeated, and those settings confirmed and dialed in.

Now that your engine is at its best, it is time to figure out where it makes the most horsepower. It really varies with the individual engine and modifications. Again, there are several runs done, and adjustments made, all documented by the computer.

When you are done, you will have a properly tuned engine, running at the right rpm to safely put out its maximum power.

Once that is done, the primary clutch should be disassembled and have the spring and weights adjusted as needed to run in the ideal range for your engine and mods.

This is the difference in guessing at something you will never get right, or just using the right tool. I am a firm believer.

I set up my sled, a 95 XLT special (600 triple) with oversized flat slide carbs and some pipes. It had also been ported and polished. When it came off of the dyno, it rocked. It was putting out 118 real live dyno horses from a formerly stock 85 hp motor. I had proof, not just on paper, but when I got a handfull of throttle. The engine ran right, at the right rpm to get the most power. It was worth every penny.

Once you have decided to do it right, find a well known shop that specializes in your brand. Chances are the dyno operator knows just what tweeks really work on a Mach Z or ZRT800.

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