Replacing exhaust

[RotaryDane]

Just wondering, maybe it is just the hooligan talking, but would fitting a different set of exhausts be as simple as adjusting the SU's leaner/richer or would larger jets be needed?

[Malc]

I have run 2 track bikes with different exhausts and SU carbs. All the adjustment is on the needle taper and jet height adjustment.For track use, I have been able to adjust them very well but as they are revving higher than they would in road use, it is harder to comment on how the 'driveabilty' would be for town use.Over ten races I tried different grades of dashpot oil and tried different dashpot springs, only to go full circle and back to near standard apart from continually adjusting the jet height by one eighth at a time and checking the plugs after full throttle bursts and hitting the kill switch and coasting in at the end of a race.Gradually weakened the mixture to the point where it needs choke at anything below 100deg.Measured the jet height and tranfered the setting to the silver track bike, was close enough to run for the the few 'running in laps' with a rebuilt engine but then had to re-adjust to suit the different engine and exhausts.So with careful adjustment I'm sure there could be a compromise setting for the road.Malc

[RotaryDane]

Sounds great! Saw what your post over in the for sale section though.

Ash, the lasers work well but are too noisy for racing without the decibel reducers fitted. The stainless lead in pipes 'brown' as soon as the bike warms up after polishing them but so far they have not burnt the baffles out. When I first put the bike together in the early 1990's, I just fitted a pair of chrome megas on some longer pipes to see what it sounded like but it burnt the chrome off on warming up!Malc

This limits the options available, better start saving for a Madden exhaust, no need to buy a peashooter to see it burn up within a few thousand km. Thank you for the advice.

[johnbirchjar]

From what I've heard,whatever exhaust system you use it will have to be made in stainless steel,anything else just melts ,J.B.

[Nortonash]

Yes, stainless is an absolute must.

[Bob]

Yes, stainless is an absolute must.

I remember circa 1968 ( BSA) running a steel exhaust with brazed joints, and if it was not for the school bus holding me up at the factory gate, I may have got a few hundred yards on mileage prior to the exhaust falling off completely.And to my shame will always remember blipping the throttle in devilment (not development) when a old lady walk past the back of the test bike, whilst I was held up in traffic, and she carried on walking with her stockings and shopping bags melted around her ankles.

[Nortonash]