Hi guys, just noticed that when my bike ticks over it hangs around 2000, drops to 1500 after 30ish seconds and then slowley cuts out.

What could this be? Its usually fine when at lights for a short period but if i leave it ticking over for a minuite it will cut out.

I balanced the carbs today and still the same.

When im riding it its fine but has the 33bhp restriction holding it back. would this be the cause?

should i check my diaphams?

any more ideas.. really bugging me this is!

It could be any number of things with the carbs, maybe electrics, the spark getting weaker as the bike idles or the spark plugs fouling up a bit. Could be the air filter got a bit dirty or the valves are a bit out.
My 3TJ was a bit like that and it turned out to be the float bowl gaskets not quite sealing, the fuel pump would still be pumping so the fuel height was wrong.