Exhaust pipe tuning

[hangtime]

Well here is the first prototype. The fit is real nice, next we'll see how it runs

[KXcam22]

Nice work! Cam.

[booneylander]

I've been doing a bit of research into pipe design and happenned on this thread. My '83 KX500 has a very different looking pipe compared to the newer watercooled Kxs, and I find that my bike has a ton of torque right off idle, but starts to fall off at fairly low rpms, so I was wondering if it might be a pipe tuning issue and whether I could easily change the pipe to give me more top-end rush.

I found this java program that you can play with to design a pipe, I have no idea if it's at all worth anything in terms of actually making a pipe, but it's interesting to play with the sliders on the right hand side to see how changing a parameter affects the design of the pipe in a general sort of way.

http://www.mh-aerotools.de/airfoils/javapipe_de.htm

[KXcam22]

Boneylander,
  If you are looking to increase the midrange it might be easier to raise the top edge of the exhaust port.  Given its an 83 I am assuming it has no power valve.  Pipe work takes some care and attention to get it to fit right - you also need to be (or know) a decent gas welder.  On the other hand, raising the port 1mm (at a time) is easily done with a small round file.  Ive done both and porting is less work IMO. Just an idea. Cam.

[KXcam22]

I forgot to add that calculating the dimensions of the pipe to match the port timing of the engine can be interresting and fun. Cam.

[Desert Panther]

And then we have to calculate:

1.Exhaust portimes.
2.Extra pipe volume/length,when KIPS is closed.
3.Temp(thinner or thicker material)
4.Application(MX/Motard/Enduro/Desert)

A pipe isn?t just a pipe,Lol

Doordie, you made an interesting point I hadnt considered, regarding application. So now that you've mentioned it...what pipe design/manufacturer would you go with for a SuMo?

[booneylander]

Boneylander,
  If you are looking to increase the midrange it might be easier to raise the top edge of the exhaust port.  Given its an 83 I am assuming it has no power valve.  Pipe work takes some care and attention to get it to fit right - you also need to be (or know) a decent gas welder.  On the other hand, raising the port 1mm (at a time) is easily done with a small round file.  Ive done both and porting is less work IMO. Just an idea. Cam.

That's interesting, I will have to look into it, wouldn't a higher exhaust port mean a lower dynamic compression ratio?

Keep the ideas coming!

[KXcam22]

Yes it does, but a few mm doesn't make enough difference to notice a decrease in compression but it is more than enough to notice the difference in midrange power. Cam.

[doordie]

And then we have to calculate:

1.Exhaust portimes.
2.Extra pipe volume/length,when KIPS is closed.
3.Temp(thinner or thicker material)
4.Application(MX/Motard/Enduro/Desert)

A pipe isn?t just a pipe,Lol

Doordie, you made an interesting point I hadnt considered, regarding application. So now that you've mentioned it...what pipe design/manufacturer would you go with for a SuMo?

That I use,DOMA,a good pipe made for overall power.
And cheap,langston-racing USA,have discount before anyway....