Siamesed exhaust pipes

Previously brian_hayes wrote:

Does any one know where I can get a set of siamesed exhaust pipes? I have a 1961 99 which had Siamese pipes fitted but I've had to destroy these to strip the engine down. The original set were siamesed very high up on the offside and must have been supplied with lock nuts attached on one side at least as the offside pipe is flanged and thus the nut is captive.

Hi Brian, The orriginal factory pipes had two normal ex nuts.RGM used to do a set which had one normal nut and one Commando type collet type ,looked a bit odd. The RGM ones were a poor fit ,I would ask for an agreed refund if you are not happy.

I got my 2 into 1 exhaustset from RGM. It was well made and came with an interesting set of split collars that allowed the exhaust roses to fit over the hollowed flange ends. That was the good news. Part of the fixing gear was also a set of very thick half-rounded steel washers that went inside the ports to help the flanges fit snuggly. I do believe that some of the later Commandos had a similar exhaust fitting. The problem with these was that they were about 5mm thick and covered exhaust port threads needed to wind in the roses and help get the whole lot leak proof. The result, on my engine, being a rose that kept jumping the exhausts threads. I fixed this by leaving out the half-round washers and making a 2mm thick flat gasket for the flanges. This worked perfectly on the cylinder head but then brought the down pipe too close to the timing cover. To cure this problem I ended up heating the pipes and correcting the bends. Which of course blued the pipes. However, after 3 years of riding in all weathers the system still looked good with no corrosion marks.