2000 SRX 700

There's Power in Technology
RELATED TOPICS: ARCTIC CAT | ENGINES | SNOWMOBILES
The Yamaha engine design staff did some work on the 700 triple triplepowerplant for the coming season. They made mods to three areas of the millwhich create more power at a wider band. The port timing and airbox hasbeen changed from last year. A new 3-D ignition timing map and DC-CDI unithave been incorporated for stronger sparkplug output.

The ignition system is nothing like the version on the '99 SRX machines.It uses a new 3-D ignition timing map which is adjusted according to inputsfrom the engine speed and throttle position sensor on the carburetor. "Thenew map delivers maximum advance for maximum acceleration from a standingstart," explained Yamaha's Greg Marier. "The TPS also adjustsengine timing for excellent throttle response and fuel economy at slowertrail speeds."

As part of the new ignition system, the magneto is constructed of a "rareearth" magnetic material which is lighter and has a stronger magneticfield strength. This technology comes directly from Yamaha's YZF R1 sportbike endeavors. The stator has an 18-pole design which allows more wireto be coiled, which in turn makes more power- 300 watts this year comparedwith 175 watts last year.

Thanks to the new CDI, all that electricity is delivered to each sparkplugonly once per revolution, instead of three times per rev. This allows thesparkplug to fire harder which facilitates more complete combustion forimproved fuel economy and higher power.

The new port timing and airbox allow the whole engine to breathe easierat high speeds. More air flows through the box because of slight internalbaffle mods.

Our dyno crew spent quality time with new SRX engine to find its happiestsetup. "We made 19 separate test passes on the SRX," noted RichDaly. "Generally, we have been able to get power by leaning out thecarburetion. But that was not the case with this sled. We needed to keepit well fed in order to make power. The band on this engine is much widerthan the '99. It's roughly 500 rpm, so clutching will be easier."

We pulled 142.0 horsepower on the SRX, which is about three ponies morethan the '99 sled. "The engine responds best to cool pipes," addedDaly. "We noted that the power tailed off slightly on the second andthird passes if we didn't cool it down."
2000 Yamaha SRX 700
Air Density: 96.3
Fuel: 94 Octane Pump Gas
RPM CBT CBHP BSFC FUEL
7200 84.3 115.9 .590 66.7
7300 84.9 117.9 .597 69.0
7400 85.9 121.0 .597 70.8
7500 87.0 124.2 .600 72.7
7600 88.1 127.5 .590 74.0
7700 89.4 131.1 .580 75.1
7800 90.3 134.1 .580 75.9
7900 91.3 137.4 .570 76.8
8000 91.7 139.7 .565 77.4
8100 91.5 141.1 .564 77.9
8200 90.6 141.5 .566 78.5
8300 89.9 142.0 .570 79.0
8400 88.8 142.0 .572 79.6
8500 87.0 140.7 .577 79.5
8600 84.7 138.6 .580 79.2
8700 81.5 135.0 .593 78.5
8800 77.0 129.0 .620 78.1


RPM: Engine crankshaft speed.
CBT: Corrected Brake Torque.
CBHP: Corrected Brake Horsepower.
BSFC: Brake Specific Fuel Consumption.
FUEL: Actual fuel flow pounds per hour.
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