Triumphrat

jimbot120

A quick question I'm sure someone will know the answer to.
I'm running twin Amal 930's on a 1965 T120. When I do a plug chop/check my plugs are black, this means I'm running rich. (that much I know.) I've tried fiddling with carbs but not really getting anywhere.
Last weekend I took my air filters off and the difference in the running and ride was insane!!
So my question is what part of the carb is causing it to run rich.
Both carbs are new prem concentrics 930's.
Main - 190
N/jet- 106
Pilot- RJ17
Valve- 3. Any help would be very appreciated ....Ta.

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Triumph Bonneville... Nothing else needs to be said!

mach1970

Depends on how you did the plug chop. If you were running at WOT and then killed the engine, you are looking at a main jet issue. That is how the plug chop should be done. You also have to make sure that you start with a set of fresh plugs. When tuning carbs you should always start with tuning the main jet and then work your way down. Of course you need to make sure that everything is up to spec first (valve clearance, compression, ignition timing, etc).

Rob

Mr.Pete

The choke slide could certainly cause it to run rich.If choke slides are fitted,do you have choke cables?
Are the choke slides pulled up fully by the cables during normal running?