BannedCR500Riders.com

My 91 CR500 has a Pro Circuit shorty silencer or cut down silencer on it.
Why would someone run a shorty?
What is the difference in power delivery between a shorty and a regular silencer?
Would it be better to get a regular silencer?

Thanks,
Jason

Why would someone run a shorty

A short silencer will help with low end power and were
big on SX and AX engines back in the two stroke days.
On your 500, it will do the same thing at the cost of
top end and over rev. It will also be significantly
louder.

dogger

Thanks, Dogger.
I ride in the woods. So the shorty should be good for that I guess.
I will probably get a regular one this summer and see what one I like.

It is but one tuning variable, but in general terms shortening the length of the exhaust system increases top end power...

We have two conflicting views, does it increase top end or bottom end? Is it even noticable other than on a dyno?

A shorter silencer increases bottom end power, a longer silencer softens the bottom and has more pull on top. Shortening the tuned length of the expansion chamber increases top end.

redrocket190 wrote:It is but one tuning variable, but in general terms shortening the length of the exhaust system increases top end power...

I'll qualify my original statement - having gone back and consulted two two-stroke tuning handbooks. Short tuned length, shorter head pipes, larger volumes and more angled diffuser and reverse cones increase top-end / maximum power at the expenses of low-end torque.

I also learned in both books that the job of the outlet pipe is too bleed off enough gas to control engine temperature without compromising the performance of the rear reverse cone. In both books it is mentioned that the length of the outlet pipe is far less important than the diameter and the resulting back pressure. When playing with tuned length is discussed it is oriented towards the length of the head pipe.

Now any open pipe in the system - something that causes a negative pressure wave - will have an effect. This would be tapered head pipe, diffuser, entry into the silencer, end of the silencer etc. will have some effect, but my take is the silencer is limited unless it influences the system like a reduction in outlet pipe diameter.