Siamese Exhausts

Hi Anthony,a photo is what we really need. Is it small or large bore?, does it come with a captive rose nut or Commando type collet , does it kick up under the gearbox or does the silencer have the dropsies?.Does it run in front or behind the frame?.Is there enough clearance at the kickstart?.We are a fussy lot here!!.

That's really helpful.   Especially the rose nut detail ,otherwise you can finish up with an ugly mismatch. Stainless is good too as plated always rust at the junction. Being a fusspot,I would like the pipes to angle down as they exit the rose nuts (I have seen some actually go up,which looks terrible) .I would also like a small kick up just before the silencer. Pipe curve looks good ,better than bends with straight bits. A good starting effort by Armours . Not yet good enough for me though. I will get mine made. Interesting that the pipes are now being made in the UK again.

If it's for the 99 then does it have the later splayed head? I bought mine from Armours in 2005 and they fitted my 88ss with the later head very well. Inside the frame and with the slight tip up. Last time I looked I could not see if the current offering was for the earlier or later head. The rose is trapped on one leg. The issue is that the internal bore at the pipe junction is not as smooth as it should be.

The 99 was never officially fitted with the DD wide splayed head,although its thought that a few at the end of the line may have been. In any event pipes made for the 650SS would fit a 99 with the DD head as everything else is the same. The 60/61 head has a much shallower exhaust port angle than the DD head .

Heyup Robert - What exactly is a "DD wide splayed head" ?  Usually the term "splayed"  is assigned to the inlet ports a la Bonneville versus Trophy.  Also for the Dominator 99SS which had the splayed manifold.  You are no doubt using it to describe the exhaust ports that have an eighty degree included angle.......as you know.   Regards as always, Howard

The DD = 'downdraft' head appeared in about 1961 on 650SS, 88SS and (whispering softly..) the Manxman.  It has a wider splay angle between the exhaust ports than the earlier head.  So pipes that fit a normal 99 (including 99SS) won't fit a normal 88SS or 650SS.  So I wonder which siamesed pipes do Armours make now?  They used to make the wide angle type.  Now it looks like they are making the narrow angle type.  Which is very odd because surely the siamesed pipes first became standard options on the 88SS with DD head?  It's also really odd that it wasn't clear last time I looked at their web site.  I rather fancy a stainless pair as mine are beginning to show their age in the corner between the two pipes (where it's difficult for chrome platers to get a thick enough layer of chrome) but they did not sell them in stainless in 2005.

The Armours site is not very clear.Are they really chrome plating stainless?, Don't think so.The early 88/99 SS with the 60 head could be ordered with small bore Siamese. the Road test I have clearly shows this with the unchopped Monos and coil ignition. Its Factory photos too.Tonys bike could be an SS but clues point otherwise.Come on Tony don't keep us in suspence!.

Just opened my copy of the compendium of Dominator road test (Norton Dominator Performance Portfolio) for the umpteenth time and noticed for the first time that the 99SS and later the 88SS tested both have coil ignition and the intermediate (not downdraft) heads. So there doesn't seem to be an 88SS published report with the DD test. No direct comparison means no evidence the later head was any better!

And of course both the 99SS and 88SS tested had siamese pipes with the narrower exhaust port angles.

I have the utmost respect for anyone supplying Norton parts when there is so much room for confusion! (Not to mention confused customers...)

To add to the confusion  there  was the brief period when the  twins from 250 to 650 came with "cheroot " streamlined silencers.Optional colour schemes  that were later standardised , Even the meticulous Neville Hinton Insisted that my 99  would have been supplied Blue/dove  instead of the red/dove  that  it was. However the 60's  was "my time"   and boy was I into Nortons.  The memory is now not so good, But then neither are the official records!!.