exhaust question on a 500cc sled motor

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rootcory

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So I needed an expansion chamber for my motor on my cart so a buddy of mine had a pipe off of a yamaha blaster 250cc quad so I cut it. And clicked it to fit where I needed it to fit

Am I hurting the performance of my motor? By running this pipe?
 

newrider3

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You need the proper pipe for the motor, 2 stroke pipes are built and tuned specifically for the engine they come on.
 

rootcory

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re

I cut it right at the seam an rotated it and welded it back together so it would rap around the motor
 

rootcory

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I know that but that will be tough to find as this motor is out of. An old arctic cat
 

theo

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one thing you can do is just try it , it might just work.
 

oscaryu1

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If it's a single cylinder (dunno), you'll lose power. You can swap pipes, but each are designed for different purposes. A 250 fatty may act like a top end pipe on the 500 due to it's larger displacement.

A for SURE restriction would be the stinger, increase the size. Most DEFINITELY increase it. You'll lose a ton o' power from that right away. If you want a quick fix, increase the ID by 2x or make it 75% larger. If you want maximum power, play around with different stinger sizes (and lengths).
 

theo

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Try it first. Rotax uses the same muffler on the 277 as on the 532 in the ultralight industry.
 

robbie

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The question of whether your pipe will work depends on what you want from your engine. If you want top performance, you want a pipe that's tuned to the engine. But I'll go out on a limb and say you don't need a tuned pipe.

The 2 stroke engines used for RC airplanes are equipped with stock non-tuned mufflers that work just fine. They're just expansion chambers with a restricted outlet, and they do a good job of muffling noise, but they don't rob a ton of power. It's considered "extra effort" to install a tuned exhaust on an RC airplane, and then you get 10 or 15 percent more power. It's a lot easier to just get a bigger engine and stick something on it to kill the noise.

The same principle applies to any two stroke engine. Any pipe you put on your engine will be OK, because you have 500 CCs for cryin' out loud.
 

robbie

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I forgot to mention that tuned pipes work only at certain RPM range anyway. If you tune your pipe to your engine running at 3500 RPM, you won't see any improvement while running at 2000. You open the throttle, then you freak out because you're going like crazy with your 500cc engine, so you back off and never reach the tuned speed.

If it were me, I would just fit the pipe so it looks cool and cuts down on noise.
 

robbie

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I suppose that is a concern. If your carburetor is adjustable you can richen the mixture to compensate, but if it's way too hot you'll want to open up the exhaust.

How restrictive is your pipe anyway? And are you running two cylinders with one pipe? The way pipe tuning works is that it creates a pulse wave that reaches the end of the pipe and travels back to the exhaust port just in time to keep your fresh fuel charge from flying out the exhaust port. That's why the length has to be just right for a specific engine running at a specific RPM. I wonder how that works if you have two cylinders firing 180 degrees out of phase, pulsing on the same pipe.

Probably the thing to do is to just use a basic expansion chamber with the end big enough to not cause overheating. As long as it doesn't hamper the flow too much it will work. You just can't count on a boost from correct tuning, which I wouldn't worry about anyway.
 

Kenny_McCormic

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Exhaust on a 2 stroke really depends on what kind of and how much power you want to make. Anything from no system at all(exhaust pours out of jugs) to a complex computer designed expansion chamber will work if and only if you jet it right.
 

juniordragsterkenny

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You're probably using the wrong pipe for the job. I'm assuming it's a Polaris motor, and the blaster pipes are tuned for too high of an rpm, plus it's a single, the sled's a twin, it'll lose power because a 500 turns about 8 grand
 
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