Topic: Motad exhaust system .

[bmwbrads]

Hi I have a 76 400/4 with a motad exhaust system the pipes from 1and 4  are very blue at the head ?. .Is this normal?. Thanks

[Deltarider]

Welcome. Maybe it's better you ask the Brits. I believe Motad was made in the UK. www.sohc.co.uk

[Little_Phil]

Early Motads were steel with chrome finish. Has the discolouration suddenly occurred? Suggest some cylinders are running hotter than others, but not unusual as Motad pipes are single skinned and often all blue a bit.
Later Motads are S/stl and discolour to a straw color.

[bmwbrads]

I have just got the bike took it for only a 2 mile run when i got back it refused to tickover plus the two pipes were very blue .Pipes slightly blue before the run .Cheers

[Tim2005]

They shouldn't blue differently. It indicates those cylinders are running too hot, which could be due to a lean mixture caused by blocked carb jets or similar, but as it is 1 and 4 they share the same ignition set so I would first check that the timing is correct and not set too advanced. Over-advanced ignition will cause overheating badly. Even retarded ignition can cause overheating.

[pekingduck]

Agree with Tim2005 - possibly from improper timing, either too far advanced OR too far retarded. Also, too rich can cause it, since an over-rich condition, like retarded ignition, can cause an incomplete combustion that continues to burn as it exits the exhaust port.

[Tracksnblades1]

Agree with Tim2005 - possibly from improper timing, either too far advanced OR too far retarded. Also, too rich can cause it, since an over-rich condition, like retarded ignition, can cause an incomplete combustion that continues to burn as it exits the exhaust port.

I’m thinking it’s a lean mixture that blues the single wall chrome pipes…
In a rich condition the excess fuel can become a coolant.. orange flames are generally cooler than pretty blue ones..

[Stev-o]

+1...sounds like it could be lean.  Pull the plugs and "read" them...