Silencer Design For 247 Cota

[ed bremner]

My Cota 247 is back working again....which is a gas.

Still plenty of work to do though....front wheel is buckled and I have another one turning up soon.

Shockers are pretty buggered....and new chain & sprockets can't be far away.

BUT most pressing problem is that it is just very VERY loud.

Problem is that it doesn't have any of the original exhaust silencer beyond the fist pipe. It has got one silencer in the place of the middle box which is from a Suzuki RGV250. Looks good but to all intensive purposes is just a through pipe.

I know that Dave Renham has got some original back boxes.....but this bike is anything but original and I am quite happy to build a silencer.....I just need to have some idea about how to design it:

What baffles? put where? filled with what?

Any other advice or links to any material about silencer design for two strokes would be very welcome. I don't seem to be able to find anything on the Web anywhere.

I am happy to consider building in Alloy sheet or carbon/epoxy quite happily - any thoughts or advice would be very welcome.

cheers

eib

[woody]

Don't know if you can still get them but I think WES used to do a replacement silencer for the 247 which replaced both middle and back boxes with one alloy silencer which exited just behind the shock.

Failing that, the middle box just needs as much volume as you can give it in length and width (door open for no amount of inuendo....) Don't bother with baffles, just a perforated core of around 35mm diameter and pack it with silent sport packing, the stuff that is like strands of wool. The longer and fatter you can make it, the better. You can make it to take the new repro Cota backbox or just to work on its own.