SOHC.co.uk Forums > CB500/550

Motad too restrictive

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florence:
After riding my 500/4 for fifteen years with a motad I have fitted a different exhaust.  This move was prompted by the shocking price that Motads seem to be now and the lack of availability of down-tubes.  (Motad now only supply the whole system).

Anyway, I was shocked and stunned to discover that the machine has suddenly more low-down and mid-range power.  Overall the bike responds better.  I can only conclude that the Motad was suffocating the poor thing.  The 'new' system is an old Laser 4-1 which I think is from the early eighties and has been lying dormant in someones garage, the sort of thing we always used to fit and now I can remember why.

matthewmosse:
The laser system is good on power but boy is it loud :o I've had louder but I found the noise from mine started to annoy me eventually so I welded up the motad. Best set up I had was a k&n filter that used the standard mixing chamber on the inlet side so it looked stock until you lifted the seat and a bsm exhaust (what silvers sell) The previous owner had found the silencer had rotted really quickly and had cut and shut a bsa rockett 3 raygun silencer on. Massively more power, fruity exhasust but loud. Could spin up the rear wheel on my outfit easily with that set up.

florence:
That's cool, the laser isn't horribly loud but I thought if it gets too much I could chop off the end part and weld on a universal silencer, but I love the idea of the raygun silencer.  If I can find one I will add it to my pile of bits.

Bryanj:
Motad was always built to be as quiet as standard so yes it is more restrictive than a Laser, but with VOSA getting all uppity with the MOT men you are supposed to be as quiet as standard now

Spitfire:
Had the same problem with my F1, the downpipes were NOS but the silencer was a BSM one from DSS, far more restrictive than the standard one, and the effect on the plugs was bad.
The plugs sooted up all the time, running from 1 to 4 they went from nearly the right colour to black, a change of plug type helped but was not a 100% cure, 4 holes drilled in the silencer backplate was the answer. My MOT tester is happy with the sound and I am happy with how it goes.

Cheers

Den

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