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Commando Exhaust interchangability

Submitted by adam_lynch on Sun, 04/04/2021
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Commando

Hello,

I am after some assistance. I wanted to replace my unbalanced exhaust headers on my 1974 850 however the ones i have ordered do not seem to fit by some margin. when you try to fit the silencer it is at least 2 1/2" too low from the standard rubber mountings. My question is therefore should exhausts with part number 06.3375/6 fit an 850? 

 

For information:

  • the silencers are pea-shooters and looking as the parts diagrams on Andover website the rubber mounting arrangements seem to be standard
  • The ones i am replacing the lower part of the pipe prior to the 'kick up'run parralell to the frame rails whereas these new ones seem follow a downard trajectory when compared to the frame rail. 

 

Thanks for any help anyone can give, 

Adam

Attachments
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Submitted by stan_thomas on Sun, 04/04/2021

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There's a lot of variability between after-market exhausts and I have yet to find a set of pipes that fit as original. And some are just rubbish.

The lower run of the pipe should be more or less parallel to the lower frame tube and never hang down like your picture. Which suggests that your problem is at the cylinder head. Are these pipes flared at the end to fit using the steel cones (Mk3 style)? In which case you should be able to pull them up. If the ends are welded then compare the upper ends to the ones you've taken off. Is the end welded at the same angle? Is the tube bend the same?

To answer your question, 750 and 850 exhausts are interchangeable. 850 have the balance pipe. And some pipes are made for different silencers so one's for black-caps will make your reverse-cone silencers stickout sideways and ones for low-level silencers angle down again to run the silencer horizontal. But they *all* run more or less parallel to the lower frame tube.

Thanks for the Quick Response Stan, appreciated. 

They are the welded type so with the rose tightened the only variability is rotation in the port. 

I held a straight edge to the down tubes of the frame rails as per attached photos and they sit very differently (in front of down tubes vs. behind). The flange appears pependicular to the pipe so i can only summise there is not not enough bend in first direction change as it comes out of the port.

Is there anyone you could recomend as a good supplier? I was thinking Andover next 

Attachments
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Submitted by gordon_robertson on Mon, 05/04/2021

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If your old original pipes fit perfectly then I would suggest having them re-chromed as I have done.

In my Norton useless parts bin I have two pairs of unbalanced front pipes that don't fit properly.

 

But good luck with finding new ones that actually fit perfectly and if you do find them please let us know where.

Submitted by adam_lynch on Mon, 05/04/2021

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Hi Gordon,

I am replacing stainless pipes as I am tired of getting them repaired. 

I got hold of an Andover pipe today and it fitted really well so hopefully I will be visitng the welder less!

 

Just hope i can return the others. 

Submitted by hans_taylor on Sun, 11/04/2021

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Adam, your ref to getting pipes repaired and welding is worrying. In an ideal world the pipes and silencers should come together with no stress at all and line up with the mounting plates. Its worth noting that some of the silencer brackets in the parts books are drawn upside down !!

I put both pipe and silencer together loose. Then tighten the silencer plate bolts, then wiggle the pipe to get it all sitting neutral, tighten the exhaust rose ring, then the silencer clamp. If you have to force them to line up something is wrong. Ps looking from the rear of the bike, they are often not equal. 

 


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