Siamesed pipes

An interesting swap 'back'. No problem starting from Cold or hot-well there should NOT be, certainly the RITA would not suffer from either unless seriously faulty. The actual spark voltage on the RITA will be greater than a mag. and the actual timing between the cylinders CANNOT vary with a RITA. But it will be interesting to see if the advance curve change improves the road performance of the bike.

If you want the RITA checked before or after you sell it? Then get in touch.

..never fitted to anything I know of for performance.  Less bulk/weight for the off road community and improved access to the drive side.  I always saw them as a fad that actually save the  manufacturers one muffler.  A sporting look no doubt but performance enhancement,  I'm not  so sure. 

The Croxford proddy commando with two right side peashooters also an odd modification unless he was counterclock circuit riding?? 

 The reinstatement of the Mag means you wont have to worry about battery level anymore...

 How do you find the 88SS Dave;  I'm interested in one as a replacement for the 99.

Cheers

Jon

Siamese pipes are useful for preventing sidecar passengers going completely deaf.

With my first rebuild in 1965 I corresponded frequently with Norton HQ and had great advice from "The Man" - JH.  He identified my 1959 99 as a "Special" with optional extras added at the works.  Essentially it was an "SS" with twin carbs, large inlet valves, polished head and HC pistons, but with what was then a standard QR camshaft (which I later changed for an SS cam and sold the QR to Barry Lawton for his Domiracer).

In the correspondence he advise that my 99 model performed better with small-bore siamesed pipes and an SS Silencer.  I never did find out how different an SS silencer was compared with a standard one but, in any case my poverty budget could only extend to a Gold Star pattern silencer!

I have seen it mentioned elsewhere since that the siamese pipes are best for a 99,  but I've not seen any mention of an 88.

I read about these recently in the "Compendium for twins". Seems there was a lot of  experimentation before we saw the "650SS".

 Small bore higher back pressure, better charge containment according to a little book I have on  tuned exhausts.

 Funny how the hallowed pattern Gold Star silencer was the go to item in the 60's.  My 60 years  stored inter had one.  When resurrected the internals were found to be completely disintegrated. Now either it was a deliberate ploy by the  previous owner, or the ravages of time as it sat in a museum.  It neither silences, or twitters (al la G.Star), but it looks the part.  Try buying a new one nowadays on a  poverty budget!

Cheers Lionel

Jon

In the '80s, a friend of mine had a siamese pipe on his 99.  It was otherwise standard.  He was pleased with it, and liked to point out the way it started resonating in mid-range.

At that time, I fitted a siamese pipe and RGS silencer to a Super Rocket.  This set-up was allegedly good for an extra 3bhp.  I liked it because it tidied the bike up, made chain maintenance a whole lot easier, and gave a lovely exhaust note, but was not loud

I have siamese pipes on my 650ss, it goes very well. 

Definitely OEM for the single carb 99SS. The press reviews credited the small bore siamese pipes with the significant performance hike over the 99.

There wasn't much else, a slightly warmer cam and a slightly higher compression ratio.

But we were 'appy.

My understanding is that  (on the 88/99 sports ) the siamese  gave a usefull increase to the mid range  and with the addition of the 650 silencer  a similar top end to the seperate pipe systems.  Don't know if they worked on the 650. I do know that my single carb 99 with RGM system  got to an indicated 110  ( at least a ton!) chasing  Stephen  riding  my VTR 1000.  I think I'm lucky to  have my rods still inside the case. Silly  sod.

88SS - 500 Class Thruxton 500 Mile Race Winner in 1960,1961 and 1962  with siamese pipes.  Moreover the bike was also second overall in 1961 and 1962 and fifth overall in 1960. Many 88 Specials and early 88SS's had the siamese pipes fitted. 

650SS -  Unlimited Class Thruxton 500 Mile Race Winner  in 1962,1963 and 1964. Fitted with twin pipes.   

Moral of this observation - twin pipes better with semi-downdraught heads......  Nuff said, Howard