Sherpa M-80 Exhaust

[myson]

Hi the baffles in the mid box have came loose inside the mid box, any ideas for an easy fix. It also has a strange after market tail pipe do you think this will effect performance.

Once I have cleaned and repaired the exhaust does it require any packing?

PHOTOS

http://s810.photobucket.com/albums/zz27/my...before%20start/

Cheers

[bultaco49]

Hi - Unfortunately there is no easy fix for this. The repair method is to remove mid box then carefully parrallel cut lower part of box off (where the widest part starts to taper to the outlet).

Inside may be some packing (normally all gone!) which should all be removed. Running through the centre of the box should be a perforated tube attached at the top end and slid into the taper at the lower end. Don't cut this tube. Slide it out with top part ot box.

Repair any damage to inside of box or tube. Clean up the perforations.

Re pack the upper box with the correct two stroke wadding.

Cut a piece of 2mm steel plate to exactly fit the cut face of box. Drill hole to allow perforated tube to fit through to align with lower box outlet. Place over box, wadding and tube and tack weld in position.

Repack the lower piece of the box and slip over the tube and push against the plate and upper part of the box. Weld a seam around the whole original cut site to re-attach the new plate and two parts of the box.

Bultaco engines will only run correctly if the centre box is packed and assembled properly.

Check the exhast pipe is free of carbon/oil build up. If not burn deposits out.

The M80 originally had a triangular rear box/spark arrestor which most people removed as it was a point where mud could build up and rub against the wheel. Your rear box looks like an early Sammy Miller after market replacment. If it is not damaged and not clogged I personally would leave it on.

There is available from Sammy Miller products a replacment mid box which is easily repacked by drilling out rivets and removing box end cap. You can see this on my Bultaco in the trials Central 'TC Garage' page (Click on link above). If you look at my Bultaco Alpina there you can see the triangular box. These are available from Spain or occasionally from Ebay. Bultaco UK sometimes have them also.

Tim

Edited November 29, 2009 by bultaco49

[fsb]

Hi. I repacked my silencers in two different ways. The tail pipe I sawed and welded after burning out and repacking it. In the midbox I cut a hole, burned out the carbon of the holes in the perforated tube and fixed a sheet metal with clinches as you can see. I used a piece from an old tube to seal it and it works perfectly.

If I understand you correctly you perforated tube is loose. Mine was it too and so I machined a ring from aluminium in the lathe which I pressed in the midbox - this also works properly. Or you just weld it together with 3 welding-points as it came originally from Bultaco.

bye, Felix

Edited November 29, 2009 by FSB

[majesty320]

Dave Renham at Bultacouk sell all the correct exhaust parts if required I fitted new parts to mine the difference was hugh

http://www.bultacouk.com/

[myson]

Thanks for all the advice, looks like its out with the tin opener one night, good job my son is a welder and has access to tig so he can do a neat job for me,

Cheers