Thread: 2 stroke hot rodding

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My family used to drag race snowmobiles in the late '80s, we had two Yamaha's, a '74 GPX 440 free air (mine - C stock) and a '76 SRX 340 liquid (my brothers - B stock). My son was the driver of both machines.

We could not do anything to the engine that didn't come stock in it including carbs, exhaust or clutch. I believe the overbore could not be over ten thousanths and still be legal, ours were totally stock. Some guys would grind off the blades on their water pumps; the rules stated if a engine came with a water pump, you had to use it; it didn't say anything about the blades though.

The "tricks' is what made them fast. Mine was set up by a professional racer, the biggest "trick" was the airbox, it came stock with one and you had to run it, and you couldn't drill it full of holes either. What he did was to put a stud hanging down from the hood, and when closed it would tip the back of the airbox so it would open up and draw air in. Made a BIG difference.

The SRX didn't have anything that wasn't stock. To make it fast we relied on "reading the plugs". We just had to have a good balance between the plugs and carb jets. We consistantly won if we were the only one with a SRX. It was fun Blowing them 440 Polaris's away with our little 340.

One big reason we won a lot is because we had a good driver, he was always first off the line and could steer it pretty good with the skies off the ice.

My son tied a world record with the SRX at a Speed Run" in Wisconsin one year and the temperature was 28 degrees below zero F.

We got out of racing them because of a rule change - our machines were too old.

The attached picture is the sign we had on the side our our truck. Our last name is Flynn, and the guy that desinged the sign played with that. I'm Fly'nn, ya we flew all right.

PS If you want to "Soup up" the Polaris, mill the heads and/or leave out the head gasket........ makes them Free Air machines FLY.