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2 Stroke !!

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Hey guys, always wondered what causes this noise on a 2 stroke, check out the video link below and listen at 02:07 into the video and drop a comment if you know :bonk:

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It coughs when he's whippin' it @ 2:04. It's probably from him gassing it and braking it in the air to correct his angle of attack. It's just from a weird combo of on and off throttle.

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He's referring to the sound that the bike makes at 2:07 when the rider hits the table top. The sound comes in right before the bike lands off the table top.

The sound he is wanting to know about is......That Flutter sound....That brief "break" in the rev which is the bike hitting the rev limiter.

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I'm pretty sure 2-strokes have em. I remember back in like 1990 when people would say the same thing when a 2-stroke made that noise.

If it is not that then it has to be something to do with the reeds and how much fuel is getting through them.

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I hear it... sounds like a metalic sound on the recording as he's getting back on the gas. I believe it could be the reed valves fluttering. Must have something to do with throttle control and throttle position. Its almost like the engine caughs, but then catches back up. Otherwise, the engine sounds like its running clean and crisp. I also agree with another comment that it could be braking in the air. That could cause the chain to whip and slap the swingarm or the case guard. Interesting question though.

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I'm pretty sure 2-strokes have em. I remember back in like 1990 when people would say the same thing when a 2-stroke made that noise.

If it is not that then it has to be something to do with the reeds and how much fuel is getting through them.

They don't have them because they don't need them. No valves to float.

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They don't have them because they don't need them. No valves to float.

that's my thought as well.

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It's from tapping the rear brake and then getting back on the gas for landing.

And 2 strokes do have a rev limiter. It's called the pipe. :bonk:

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It's from tapping the rear brake and then getting back on the gas for landing.

Yep, that's what it sounds like to me. But it sure is brief!

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It's from tapping the rear brake and then getting back on the gas for landing.

And 2 strokes do have a rev limiter. It's called the pipe. :smirk:

Cool, so it's basically like a type of engine bog or a power surge for a brief second where the engine hesitates to keep up lol ?:bonk:

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Cool, so it's basically like a type of engine bog or a power surge for a brief second where the engine hesitates to keep up lol ?:bonk:

When a 2 stroke hits its peak revs the power starts falling off quickly and the motor makes a distinct sound.

Here listen to the master of the rev limiter right off the first jump.

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It's from tapping the rear brake and then getting back on the gas for landing.

And 2 strokes do have a rev limiter. It's called the pipe. :bonk:

actually there is a few things that can limit the rpms in 2 strokes, there is exhaust port timing, the pipe, ignition timing, even jetting can play a role but there is no electronic rev limiter unless you have a pw 80, those thing bounce off the limiter like a 4 stroke lol

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Don't know what the sound was, but he was railing, awesome video.:bonk:

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Its what I have always called a 'lean pop', im not sure exactly why they do it, normally when a small bore 2 stroke is jetted real nice, and you do like jimmy does over that jump, ie, wide open throttle, your get that 'pop' noise, my Cr134 does it too, more so since changing my CDI.

Im pretty sure its exhaust related, ie, fuel throttle, no load, pushing more mix into the pipe that then ignites in there, giving that pop. My bike will actually spit a tiny flame when making the 'pop' noise.

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