Exhaust system mod

[tschisi]

Hello!


I own a 1990 KX500 which looks pretty much original at the moment.
http://img163.imageshack.us/img163/8090/kx500.jpg

I will do the rear fender mod in the next days, which leads me directly to the next project:
Making the exhaust system look a little bit more up to date, but keeping the original muffler and the engine "quiet".
My idea was to place the muffler angular behind the side plate, hiding it a little bit.
With some modifications of the air box and self-made pipes that could work.
http://img94.imageshack.us/img94/553/kx500eh.jpg

I?m only afraid of the increase of "flow-resistance", caused of the "S" in the pipe.
Has anyone ever tried this or knows how it will affect the engine?


thx

[KXcam22]

The S pipe will not restrict the flow at all but the real problem is that the path of the pipe is right through the airbox.  Plus the pipe needs clearance so it doesn't melt the plastic so you would end up cutting a large hole in the airbox. Then possibly the filter won't fit.  I understand what you are wanting to do but it is a lot of work to get there.  Besides, have a look at the euro 450 race bikes.  They all have a huge silencer that sticks up above the rear fender. Hope this helps. Cam.

[tschisi]

Arrgh, that?s not what i wanted to hear, but i guess you?re right.
Another problem, that just came to my mind, could be thet the rear wheel would probably collide with the muffler when landing a jump.

What do you think about shortening the muffler?
The rear mounting hole could be used as the front mounting hole.

[jfabmotorsports.com]

They can be shortened with minimal work. I have done this to a few, just a little noisier.

JFAB

[tschisi]

Just a little noisier?
Sounds good, i heard it would become very loud.
I think i?ll give it a try...

[jfabmotorsports.com]

I cut only about 2-3 inches off. Just enough to clean it up from a good encounter with the ground. I was not too loud to me, my Dad thought it was though.

[Uzi9mm]

JFAB,

If you shorten the pipe, will the decreased pipe length change back pressure and your powerband?  Could you post some pics of your bike?  I would like to shorten mine if won't reduce performance.

[jfabmotorsports.com]

I don't know that I could tell any performance lose or gain. I just did it back in the day because I didn't have the money to buy a new one every time I flipped the bike. I will have to look for the one that I shortened on the last 88 that I bought. It was a mess so I gave it the treatment. I will post pics if I can dig it up.

Also, Stewart can probably tell you if it make any difference with or without. I'm sure he has dynoed it both ways.

JFAB

[kaw rider]

don't worry about 2-3" off of the muffler. These motors run hot as it is. Most guy can't feel a 2hp loss.