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Triumph TR6 - Quick question Re: Noisy deceleration

Here's a quick question for all:

When decelerating, I get some backfire through the exhaust, sometimes worse than others. It may be the carbs that I just attempted to rebuild but I'm thinking its more likely the Petronix timing.

So, advance or retard? Suggestions?


most probably the carbs ,The temp compensator possibly, This was discussed a couple of years ago and I don't recall the answer.

I bet it is the GD by-pass valves....sorry for the bad words...I just hate the stupid things.
Rick C
Rick Crawford

Do a quick search for by-pass valves. That is most likely your problem as stated previously. They are likely "floating" as per the Bentley manual. Most of us have blanked off the bypass valves completely with plain gasket paper. However, before jumping the gun you may have the adjustable type and you can follow the Bentley to see if you can get them tuned and not floating. If your bypass valve has a flat head screw on the end it is externally adjustable. If it does not and has a brass blanking cap instead you will have to dismantle it to clean/adjust them. The big three sell gasket diaphram kits for the bypass valves. Or you can just blank it off while you have it apart.

Have you checked damper oil? Mine was leaking down, and low or no oil letting the damper open, lean the mixture, and popping on decel. Might be worth a look?
Rod Nichols

Kudos to BBS! Installed a blunked off by-pass valve gasket and problem solved. Many thanks all.
73 TR6 Toronto

This thread was discussed between 31/07/2006 and 08/08/2006

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