What is this thing?

I was cruising through the pit area prior to the Supercross in Houston, and saw this. Can anyone tell me what it does?

Seems pretty trick.

I guess I should add it was on a works YZ.

http://i238.photobucket.com/albums/ff33/road_hard72/yamacan.jpg

I am not totally sure but I believe it is a preliminary expansion chamber like the FMF Megabomb header. The reason I think this is because I believe I saw an FMF Megabomb header ad in a motorcycle magazine with some pictures of other companies' headers ripping off the FMF concept/design.

go to the yamaha website and check the GYTR pipes for the yzf's it's in there.some kind of a power bomb type head pipe i guess.

go to the yamaha website and check the GYTR pipes for the yzf's it's in there.some kind of a power bomb type head pipe i guess.

thanks. I found it.

"Head pipe has special patent-pending resonant chamber design."

gyt-5xc93-73-ss-500.jpg

Its just as ugly as the AIS

ok, but what's it supposed to do...it's on the Acropovic web site, but the pic they show doesn't look anything like the one one I posted. Agreed it's some type of resonance thingy. Just don't understand the "science" behind it all.

isnt that supposed to make the pipe think that the head pipe is longer for more torque? Head pipes arent very smart

isnt that supposed to make the pipe think that the head pipe is longer for more torque? Head pipes arent very smart

You nailed it...on both counts.

we like to call it the pooper can and yes that is correct.

it is supposed to equalize the pressure.

It serves two functions (well......maybe three).

At medium engine rpm's it causes a delay the high pressure wave that travels from the exhaust port to the tip of the muffler. This happens because the extra voulme in the 'can' absorbs some of the pressure as the exhaust pulse passes by and releases the pressure once the pulse is past. The delay in the pressure pulse causes an equal time delay in the low pressure (reversion) wave that travels from the muffler tip back to the exhaust port. The arrival of the 'reversion pulse' at the exhaust port should occure slightly before the valve closes. If the pulse arrives at the exhaust port too early it will dilute the fresh fuel-air charge in the cylinder with exhaust gasses and cause an unwanted pulse wave to travel back through the intake track and carburetor. If the 'reversion pulse' arrives at the exhaust port too late a small ammount of fuel-air charge is lost out of the exhaust system with no benefit to power production.

At higher rpm's the 'can' adds to the total volume of the head pipe and reduces back pressure.

The 'can' will also slightly reduce sound output.

The main advantage to this type of exhaust is it allows for an increase in midrange power without any detrimental affects to peak or top end power production.

It serves two functions (well......maybe three).

At medium engine rpm's it causes a delay the high pressure wave that travels from the exhaust port to the tip of the muffler. This happens because the extra voulme in the 'can' absorbs some of the pressure as the exhaust pulse passes by and releases the pressure once the pulse is past. The delay in the pressure pulse causes an equal time delay in the low pressure (reversion) wave that travels from the muffler tip back to the exhaust port. The arrival of the 'reversion pulse' at the exhaust port should occure slightly before the valve closes. If the pulse arrives at the exhaust port too early it will dilute the fresh fuel-air charge in the cylinder with exhaust gasses and cause an unwanted pulse wave to travel back through the intake track and carburetor. If the 'reversion pulse' arrives at the exhaust port too late a small ammount of fuel-air charge is lost out of the exhaust system with no benefit to power production.

At higher rpm's the 'can' adds to the total volume of the head pipe and reduces back pressure.

The 'can' will also slightly reduce sound output.

The main advantage to this type of exhaust is it allows for an increase in midrange power without any detrimental affects to peak or top end power production.

Dang...anything to get a horseleg up on power:banghead: What'll they think of next:thinking:

Thats a good explanation grimjim!

I laughed, recently i read someone said 4-strokes don't have reversion. Its a science that most cant understand.

Thats a good explanation grimjim!

I laughed, recently i read someone said 4-strokes don't have reversion. Its a science that most cant understand.

One of these days I'll figure out how to make a '2 stroke style expansion chamber' for my YZ450.....................I just wouldn't want to fall over in the rocks!

isnt that supposed to make the pipe think that the head pipe is longer for more torque? Head pipes arent very smart

Aha! The old trick the headpipewith a can thingy....I should've known!

Thats a good explanation grimjim!

I laughed, recently i read someone said 4-strokes don't have reversion. Its a science that most cant understand.

Ok, I'll admit it...it's a science I don't really understand. But Grimm did explain it very eloquently!

Have some gas, Bro....

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