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Hey guys,
I once again need your help with my 74 DT360. I'm very close to getting it registered, the only issue left is the exhaust noise. To me it seems like somebody removed whatever had been in the muffler originally and later replaced it with a steel pipe with a few holes and some insulation wool. With his setup, the bike is way too loud to be street legal here, so I'm wondering how the inside of that muffler looked originally. Maybe someone has some photos or a spare muffler laying around for some photos on the inside!
Highly appreciate your help as usual!
This is a cool picture sent in by Schu....however, this will not be helpful to Leon. But perhaps, it will help someone in the future, who has a 1975 -1976 DT250B/C / 400B/C model.
Ok ... the 1st one i opened did not have any sound dampening packing, but I noted that it had a piece with spiral shaped blades, that spin the exhaust gases outward ... towards the outer casing walls.
This piece was welded firmly in place at a depth of 126+mm (5 inches), and had a bullet shaped cone in the middle.
It appears to me that the previous owner had knocked this piece out of yours, and then installed the longer pipe with holes drilled in it.
The second one I opened up, had a real dense fiber type mat still in place. This mat absorbs sound energy.
SEE PHOTOS BELOW:
Hey Dave,
Thanks for your reply. The allowed noise level depends on the vehicles age. For the DT360 81dB are allowed at 4150RPM while stationary and 86dB during a low speed drive by, that’s what the original „ABE“ (General operating permit) from 1973 says. It will also be measured according to the exact procedure from back then, but the TÜV engineer still has to research the procedure. From what I could find I actually seem to have a tolerance of 26dB when measured with the new procedure, since back then they measured from around 7m (23ft) away, now it’s only half a meter (1.6ft) but at a 45° angle to the exhaust, so I‘m probably already good with the setup I have.
Anyhow I‘m interested to see how the original muffler was designed, on longer rides the bike is pretty loud even for someone who enjoys the sound 😆.
Kind regards
Leon
Hi Leon . . . How do they do the sound test? . . . 15 meters away, and driving by a sound meter?
Do you know how many decibels Germany allows?
The reason I ask, is because the original stock DT360 silencer may not even pass with todays standards.
Give me a few days to get the baffles loose, as they are both rusted tight.
I think your current set-up may be quieter if you leave that long pipe out, and just wrap the short pipe (outlet pipe) with sound dampening insulation/wool.
I bought a modern silencer for my DT360, and people have said it is much quieter, and gives more power. I have not personally tested mine yet.
See pictures below: