simonro1, Nice looking adaptation for silencer.

Maybe to late to ask, but what rear wheel/hub are you running?

Looks like a great job and cures the rear brake on the right problem;

no more cable compression/leverage trouble.

Thanks

Larry

Presumably Bultaco wanted to keep the thing quiet (and it certainly was) hence the weight.

Back in the day one of the guys wanted to make a silencer for a special he was making and used the work facilities to x-ray a clubfoot. Seems there's a lot in there.

The silencer was very advanced back in the days, the system is based on hollows in different volumes connected either through openings in different sizes or tubes in different length and diameter. They worked the Helmholtz-Resonator works as absorbers thus reducing the sound and gives a steady air resistance at the outtake of the middle section of the exhaust.

These system was also used by brands like SWM, Fantic and Montesa, so it was very commen. The silencer has too a longer live time as he can't clogg so well, the system works also in rducing noise better then any silencer based one a holetube and insulation.

The standard layout measurements their layout and "how-to" was dicussed in Trialsport issue 87, 107 and 128. I think it's not so easy to create something likewise for the Bultaco two stroke engine as the pipe section has barly any typical resonance function so the silencer must have it's part in it.

Why aftermarket silencer/exhaust,accep from the weight.

A wise man,,good trialsrider,and developer of two trialsbikes said one day to me:Do you thought we where stupid in the factory when we made the exhaust.