This looks way cool, and very thought out.
I can follow the concept of the gas passing through and around the first diffusing plate   and back into the pipe at the end of the neck and out the 2nd diffuser plate. But I am unclear as to the cut marks in the side of the baffle? From the end view it appears that the bell is welded around the baffle preventing any gas flow from escaping around the outside of the baffle. What function do the cut marks play in the flow of exhaust gas?
Can you also provide some input on diameters and dimensions?

This looks like something that I can get my muffler guy to help me build.
Great job Jim!!!

diamond jim wrote on 06/22/09 at 10:18:11:



How much has this whole set up cost you?

Pipe and baffle: $22.16.  

$5 of that was a tip cause muffler dude has been pretty cool helping me out with this stuff. $2.16 was cause I had to go to Advance Auto to get the piece for the diffuser cone. He didn't have any that small.  Already had the square steel for the mounting bracket.

Sorry for bringing a thread back from the dead, but I've been wanting to put a drag pipe on my Savage, but am worried about it really messing with the back pressure and tuning. It sounds like this was a design that worked pretty well, but since the pictures are down it's tough to find instructions on replicating it. Any ideas?

Alternatively, I was looking into BCB drag pipes, but it looks like they may have discontinued them

If there are any proven designs or aftermarket drag pipes that work well with a Savage, I'm open to that, too.

Thanks!

Diamond Jim was an engineer and worked on this pipe/baffle for some time with quite a number of variations before he came up with a design that actually worked.  His design is the only one I have seen that works pretty well on the Savage.  His bike had a stock engine with jetted stock carb and this exhaust.  His bike dyno'd at 30-31hp and ran pretty smoothly with an occasional hiccup.   He made slight changes to the body which made it look long and lean.  It was a very pretty bike.  I called it Black Beauty.
My son bought it from him when he thought he would never be able to ride again, and then sold it a year or two later.


If someone can recreate this pipe from his description that would be helpful for folks here who really want a straight pipe exhaust.

If I follow the thread I think have done something similar on both the Savage and a little Honda 250 twin.  I did this same thing on a little Honda 250 twin and it worked great.  Here's pics of what I have done on my Savage engine.

The header is 1 5/8" 16g 304.  The insert is 1 1/2" 11g steel on the large diameter and 7/8" 12g where the cuts are.  The baffle is about 6 inches long in the 7/8 diameter section.  I have been 'adjusting' the open area by adding or subtracting cuts.  

I started with 9 cuts and now I'm at 7.  I ran it for a short time at nine cuts and then welded up two based on plug color and backfiring.  It's maybe a little rich based on the last plug inspection but I'd rather be a tad rich than lean.  Smokin Blue took it for a short spin and felt that the back pressure was OK based on his experience.  

On my little Honda I've added and subtracted a lot of baffle due to some carb issues (in hindsight).  But I was always able to improve the tuning substantially by opening or closing the baffle based on how it was running and the color of the plugs.  I did also learn the length of the baffle is important.  Too short and the noise is piercing at mid and upper rpms, a longer baffle smoothes it out a bit.

Here's a link to a short video from when it probably had nine cuts in the baffle.  https://www.youtube.com/watch?v=G9yMYHVa4mk