Misc: Everything Else Exhaust AND carbs.

[Albervin]

I decided to fit the silencer from my Shadow onto my Rapide as an experiment in breathing as well as power. The result...
The Rapide with Shadow silencer ( a Toga absorption type) shows a much better roll on throttle response than with the spiral baffle. Rolling on 3rd gear gets to 70 mph much cleaner and quicker. However, on the roll off down a hill I get some serious backfire with (what I am told) a decent flame out of the pipe. Not quite so bad on the flats. Obviously I need to re-calibrate the carbs BUT in which direction? Advice please. Currently using 276 with 170 main jet and needle in 2nd notch. 7.3:1 compression and cams somewhere about standard. Ignition set at 34º.

 

[Vincent Brake]

Tighten exhaust nut?
Ignition Anvance unit?
and the rest.

but i think many many know more about it.

why dont leave it? its nice to have some fire from an exhaust.

I have to say, i do like those absorbsion pipes (not silencers), one can pass a posse of horses silently. and make it very loud when wanted

 

[Albervin]

I checked exhaust nuts and both tight. Electronic BT-H ignition.

 

[passenger0_0]

I would give it a few miles first before making any changes as you might simply be burning off carbon. You might recall that more power equates to higher combustion temperature.

 

[Albervin]

I would give it a few miles first before making any changes as you might simply be burning off carbon. You might recall that more power equates to higher combustion temperature.

Good point. The Shadow was very smoky when I bought it. Probably a fair bit of carbon in the pipe.

 

[timetraveller]

Have you checked the joint where the silencer fits over the exhaust pipe? If there are any doubts about whether this is air tight refit it with some clear silicon mastic to act as a seal. The clear will stand the heat for years.

 

[Albervin]

Thanks Norman. I will check that. I know the previous owner had a suspect exhaust nut and coated the thread with silicone. Not my idea of a good job but it worked for thousands of miles.

 

[macvette]

Thanks Norman. I will check that. I know the previous owner had a suspect exhaust nut and coated the thread with silicone. Not my idea of a good job but it worked for thousands of miles.

I had something similar at the begining of the year, banging on the over run, cant say I had flame. The nuts were tight but when I took the pipes off, the fibre gaskets had deteriorated and crumbled away. They were 10 yrs old. Replaced with copper ring type which sorted it.

 

[Peter Holmes]

I think using silicon sealant on the exhaust header pipes and other connections is a great solution, I have been using it for years, I think relying on the flange to be degree perfect where it meets the hard gasket in the head is somewhat optimistic, I use the high temperature silicon sealant that woodburning stove installers use, and if done properly they issue a Heatas certificate stating that the chimney liner etc. is gas tight, and when the burnt gasses leave the stove they are very hot indeed. The joints are easy to detach when you need to, what is not to like?

 

[BigEd]

I think using silicon sealant on the exhaust header pipes and other connections is a great solution, I have been using it for years, I think relying on the flange to be degree perfect where it meets the hard gasket in the head is somewhat optimistic, I use the high temperature silicon sealant that woodburning stove installers use, and if done properly they issue a Heatas certificate stating that the chimney liner etc. is gas tight, and when the burnt gasses leave the stove they are very hot indeed. The joints are easy to detach when you need to, what is not to like?

What brand did you use? I have tried to research heat resistant silicone sealants but the reviews I found have not all been positive.