Having recently opened up the "middle box" to replace the perforated tube and repack i thought i'd have a minor dry build to check the fit and see if i could improve what looks like a slightly loose fit to the silencer.So crankcases and barrel in the frame i offered up the pipe to the barrel to find the stud spacing on the exhaust flange and the barrel are different! The holes on the flange are 51mm between centres and on the barrel they are 57mm.My bike ( a 191 ) was a box of bits when i got it and was missing the top end .The barrel i've got is a 325cc one,i think off a 183,and it has the 159 stamp on it.I know the previous owner bought the bike as one of a pair with his mate and wonder if the exhaust was off the other Sherpa.I did think it might have been off a 250 but the diameter of the pipe does match the casting on the barrel. It wouldn't be difficult to engineer a solution, just wondered which bit's wrong.....any ideas?

It will be a 250 exhaust (from model 158 onwards) The stud spacing is closer together on the 250. The early 325cc bikes up to model 151 share the same stud pattern as the 250 but from model 159 the stud pattern was wider.

Cheers Woody , thought that might be the case.I'll probably make a new flange to fit and cut the pipe where it joins the box with a very thin cutting disc to change them over.As i said the pipe isn't restrictive but do you know if there is any difference in the system inluding the "club foot" silencer between the 250/350 other than the flange? Don't wont to go to the trouble of sorting it out to find that it strangles the motor.

I'm not 100% certain, so don't want to offer an opinion that may be wrong. I'd guess though, that the internal perforated core in the middle box and the one in the lower half of the clubfoot are the same for 250/350. I'd also guess that the baffles in the upper half of the clubfoot are the same.

What can differ is the size of the outlet of the middle box and the inlet of the clubfoot - not just from 250 to 350 but also on different models of the same capacity, but I'm not sure which exactly, just what I've noticed from different exhausts I've seen. I think, for the 350 at least, the later the bike, the bigger the connection joint between middle box and clubfoot.

I'm not sure if the clubfoot belongs to the bike or is the other half of the 250's exhaust.They do fit together though.The inside diameter of the end of the middle box is 32mm and looking back through it to the perforated tube it looks quite unrestrictive.The pipe into the clubfoot is only 27.5mm diameter and it's joined by a 50mm long tube on the inside of the middle box and on the outside of the clubfoot.To me that seems a bit restrictive.Any idea if these are the smaller or larger size pipe? If it helps the clubfoot has 13717-043 stamped on it ( might not be a part number though ).

13717-043 would be a Alpina clubfoot.

On the Soler models the front pipe/ middle box are the same on 250/350 models, its only the coupling to the cylinder that is different.

The clubfoot is a different part no. but I think is only a different in the length of pipe where it joins the middle box as the frames are not the same.

Edited August 28, 201213 yr by mrb505

Wait a minute I just went and had a look at my M183 clubfoot, number on it is 13717-043 and I'm pretty sure it is the original one.

The Bultaco parts book says it should be 15917-043 and the 250 should be 12217-043 so maybe the 137/159/183/191 clubfoot were all the same

http://sherpamanuels...bel/2.16 Escape

So your 183 has the 27.5(ish)mm pipe where the middle box joins it? If that's the case i'll start making a new flange for the front pipe then offer it all up and see what else needs doing.

Yes 27.5 OD