Exhaust Gas emissions

[shazaka]

I have just bought slip ons ( caps ) for my Heritage Softail Nostalgia. I am concerned about how the gases are emitted through the discs as they are very tightly fitted and there doen't seem to be any gaps for the gas to escape from. Anyone know?

I am probably being over cautious and paranoid but any explanations welcome. Thanks

[bschultz]

I would suggest visiting the SuperTrapp website and look at the FAQ's at the "Resource Center".

[kz550]

I own two of the 4" x 13" Aluminum Racing Series slip-ons, where the inlet diameter is 60mm. I won't post pics again here, but <here's> a link to one of the two threads and both are linked to one another.

There is a common misconception about SuperTrapp exhausts being restrictive or even too restrictive based solely on the appearance, especially of a closed end-cap system. It would seem that there truly wouldn't be much area for exhaust gases to escape. However the opposite is true. For instance, on my 900cc motorcycles, I can run as little as 6 diffusers. (Third picture down <here>). Performance is roughly equivalent to the stock exhaust. That's because even though the visual gap may only be about 0.95 CM, it's a radial gap whose circumference is over 32 CM. I'm no mathematician, but I can tell you that the stock muffler's 36mm outlet translates to whatever the area is of 6 stacked 10.16 CM diameter diffusers. If I up that to 10 diffusers, it is beyond uncorked, which is why I max both my machines out at 9 diffusers.

Acceleration, throttle response and power are impressive. And if you don't already know this, the ZX-9R is a RAM-air engine design, so even at 9 diffusers, which measure a stacked width of only 1.4 CM, it's more than adequate to top the bike out in top gear, which I haven't done. However I have taken it up past 150 MPH more times than I would want to count and have witnessed it pulling willingly past 167 MPH on an air-strip whose runway is 1,474 M (4,800') above mean sea level. That should give you some sense of how much power is being delivered. I'm a firm believer that when tuned right, the SuperTrapp's scavenging affect works as advertised. I'd put money on it.

On occasion, I've placed my hand up to the diffusers when the bike is idling or sometimes when I rev it and there is clearly no restriction of the exhaust gases. They are venting perfectly fine.

[sportthedog]

agree with kz but with additional comment.
Over time the gap between the discs on my supermeg has decreased, is less now than when it was new.
Not sure why the gap is smaller, maybe heat maybe overtightening but my header is hotter than it was new.
I'm doing 2 things (maybe 3) to fix:
- getting a new 12 pak of 4" discs
- having the header ceramic coated inside and out
- (maybe) buy the 4" end cap from LA Choppers that can be opened or closed or anywhere in between.

[jwells]

Try cleaning them occasionally, carbon builds up pretty quickly, also be sure not to overtighten as well.


QUOTE=sportthedog;11938]agree with kz but with additional comment.
Over time the gap between the discs on my supermeg has decreased, is less now than when it was new.
Not sure why the gap is smaller, maybe heat maybe overtightening but my header is hotter than it was new.
I'm doing 2 things (maybe 3) to fix:
- getting a new 12 pak of 4" discs
- having the header ceramic coated inside and out
- (maybe) buy the 4" end cap from LA Choppers that can be opened or closed or anywhere in between.[/QUOTE]

[kz550]

I have just bought slip ons ( caps ) for my Heritage Softail Nostalgia. I am concerned about how the gases are emitted through the discs as they are very tightly fitted and there doen't seem to be any gaps for the gas to escape from. Anyone know?

I am probably being over cautious and paranoid but any explanations welcome. Thanks

Thinkingof.gif wait.gif You're welcome? Hello?