Hi StotheH and as Bigted said
If you have sucked on the decompression valve and it moved in and out as it should I'd say that it's working.Removing it would only help to up the revs even more.As they are installed not only to help control the revs but to also make it easier to start.It helps to stop a 2 stroke from kicking back and boy can that hurt.
As Bigted said the diaphragm in the carby could well be the issue.
What I'm trying to work out is why does it have 2 brass washers.I've only ever found brass washers in a G4 carby not an LM,but that's only from what I've found.The fact there there is two makes me think it's had some problem before.
Something else I've found recently on a couple that I've had here is the two vacuum hoses to the carby being around the wrong,it doesn't make a huge difference but it did slow them down in rpm as well.
I think it was the one coming from the engine block to the top of the carby and the hose on the inlet side (bottom of carby) goes to the decompression valve.
The two I had were around the other way and they weren't running quite right until I turn them around the other way.I guess there is couple of things to look at see how you go.
Once again
