DG Pipe modification

[Robert58]

Does anyone have any info, pics or specs on how to do stinger and silencer modification on RD400 DG chambers ?. The old site had some info that I think was done by Coolhead using 3/4'' emt and reusing DG silencer with mods to that.
The DG's exhaust outlet stock is 1 1/8''.
It also said the stinger most be smaller than perf tube. Just purchased a flux welder to fix lawn mower, DG's next.
Anyone else done it?

[rodneya]

I have started doing mine, but have had other projects keeping me busy. I might actually just cut off the back cone and make new ones as |I dont really like the way it looks after making the end smaller.

The old forum mentioned stinger should be 270 to 295mm long and ID 25 to 27mm

[Frank B]

Here's a link to some pics I found of the mod, I think the owner is a board member 

https://drive.google.com/drive/mobile/folders/0BzYSyzijpCvrMnZmS1FIZXVMQTQ?usp=sharing

I may still mod mine some day even though they're not on my bike anymore

[rodneya]

Here's a link to some pics I found of the mod, I think the owner is a board member 

https://drive.google.com/drive/mobile/folders/0BzYSyzijpCvrMnZmS1FIZXVMQTQ?usp=sharing

I may still mod mine some day even though they're not on my bike anymore

Noooo

The only reason I started the mod was to get rid of the pig ugly DG silencer section.
i got a set of shorty silencers from Tyga that should look pretty good. They are made with an o-ring in the inlet side that fits perfectly wit a 1" stinger pipe.
Now they are selling spring mounted silencers that look even better

[Frank B]

 Tygas on DG pipes ??

[Robert58]

I found these Tyga's not sure if they are the shortys , they have 26.50 mm inlet , for stinger  1'' EMT is    27mm ,1.163''.

[Frank B]

3/4 conduit or 24mm id tube would be a better option for stingers. Step up with the perforated tube, same size as the stinger would extend the stinger and decrease the bleed rate and overheat the engine.
This has all been hashed out before, unfortunately all lost on the old board..

[m in sc]

^ yup. unless you want the silencer to act as the stinger somewhat 

[rodneya]

I found these Tyga's not sure if they are the shortys , they have 26.50 mm inlet , for stinger  1'' EMT is    27mm ,1.163''.

Shorty is part no EXSL-0067

[2strokesforever]

https://www.denniskirk.com/drag-specialties/baffle-w-fiberglass-wrap-for-2-in-od-exhaust-1861-0913.p4407406.prd/4407406.sku?fbclid=IwAR3VBl9nBmSzznh6UC5yWOMuSwcnxQk-XsYGRSeiGSRx9X2Yl0laZED4QTw

Look at these for silencers, cheap and built pretty decent.

just as others have stated, keep the silencer larger than the stinger or you will have just created a longer stinger.

Have fun experimenting, you can really change the characteristics of the bike with a different taper on the end cone and the ID of that stinger. Just make sure you jet down and not up.....

[teazer]

Robert58,

The reason that people cut off the muffler portion and add separate cans is all down to fashion and not really performance.  Back in the day, most pipes were made the way that DG's are because it simple and much stronger than a relatively heavy and unsupported muffler flapping about on the end of the pipe.

Denco, Bassani, J&R, Micron and so on all used a large diameter outer pipe to contain the muffler and to attach it to the main chamber body.

I have a set of Spec11 pipes on y RZ that basically use the same approach.  I also had a pair of Swarbricks on a TZ that regularly broke the stinger off and left the muffler at the side of the track.

That said, if you want to go to a can type muffler, I would recommend putting most of the stinger inside the last cone to keep noise down and to shorten the length of stinger flapping about. And get a muffler where the ID is slightly larger than the stinger OD.

[m in sc]

um, not for style , the dgs dont have a stinger out of the final cone to the muffler. so it goes to an open chamber then gets pushed out of the muffler, which is terrible. adding the stinger does help, ive done a few sets myself. 

[Robert58]

 I was under the impression from Coolheads pics and what M in SC said that the cone on the DGs were not very " Coneish" and when you cut away silencer you could reshape the cone and add the non existent stinger. Since like the Tyga shorty is 1'' I was going to get 1'' EMT or mild steal , sounds like i should get 3/4'' instead and get 3/4'' to 1'' reducer.
From watching some videos  by Dave AUmechanic  on how to design expansion chambers it all gets a bit intimidating.
If I dont modify and switch chambers which brand can you buy that are better than DGs and can keep the stock pegs without going to rear sets?
Or could you modify cone and add stinger internally and just put cans back?
I found in my paper library Coolheads pics and one post on subject, I scanned them in

[m in sc]

j&l retros are a good option.

specII as well.

[Robert58]

Forth pic