Thread: 2 stroke hot rodding

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Thus far all i have ever worked on are two strokes.

Opening up the exhuast is a good idea, DO NOT, i repeat DO NOT run straight pipe! she will run but like crud. not to mention fouling your plug, and all sorts of other nasties. i recomend looking up the "two stroke tuners handbook" i tried to attach it but its 7.7 megabites lol. I have not yet read it in its entirety but it looks really good.

tune your carb real well. i know this sounds like a no brainer but i got a 1978 Honda Express Moped to really scream yesterday after a simple adjustment. (opened up the jet needle one notch)

Cook your muffler on a bed of red coals 1/2 to full hour on each side to burn off any carbon build up.

definetly check with a 2 stroke tuner whom is familar with your engine. porting these bad girls really helps but if you mess up you will dearly pay for it .

you can gasket/port match without any troubles. leave the actual port in the block and crank to the pro.

depending on your comp ratio try some higher octane gasoline(or add a little race fuel to your tank). if its 6.2:1 like my two old ladies that will hurt performance instead .

anything you think will benefit, HOT RODDING isn't it great?!

Best of luck buddy!
2-stroke all the way,
-CJP

On the old Clinton go-cart engines, the round transfer ports were squared up and the dividers thinned as much as possible. IIRC, the intakes were squared on the bottom only, or the intake timing was changed too much. That's about the era that I gave up on two-strokes! I hate 'em! Any sled I ever took for a drive, I ended up walking home.
My brother had a 440 TNT, seemed like a good runner. We put the engine in a newer Free-air sled, aluminum instead of steel frame. Not as tough, but lots faster.

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.