When you lowered the needle clip; this raises the needle in the jet = richer.
You fitted larger main jets ( little effect at idle) = richer.
Worn emulsions = richer.

You seem to be adding more and more fuel to compensate for too much air.

Too rich a mixture at idle causes the revs to dip below the set rpm and then raise.
Too lean a mixture causes the idle to hang.

I still think you have a significant air leak ( you state the throttle snaps to the stop and mechanicals are eliminated)
and are trying to tune round it, making the rest of the rev range poor.

Too much fuel does not equate to higher revs; the opposite is true = too much air .

http://www.factorypro.com/tech/tech_tun ... gines.html

A general overview is above, but you should not need to do a great deal of what is included unless significantly different carbs or exhaust have been substituted.
Them engines pretty much run good on the std settings.

Are you sure the carb/head rubbers are not leaking and the air box/ filter is secure.. ?

Sorry, I didnt describe that very well.

I have moved the clip position closer to the flat end (moving the needle lower into the jet) thus making it leaner. this has reduced the racing at idle slightly.

Test ride today, Idle was better than it was but is still holding slightly at about 2000rpm. Not too bad I think for now I will live with it. Think I will save some £ and renew carb seals and new needles & emulsion tubes.

Thank you all for your help and suggestions, If I manage to fix the problem in the future I will post on Forum to tell you what cured it.

thanks....Paul

Maybe the you can adjust the air bleed screws a tad to find the last part - it's just a lot of messing around

Maybe try a carb sync.
It may just be possible that the "control" carb, no. 3 I think, is against the idle stop but the other 3 butterflies are
being held open by the sync. adjuster screws.

Still hanging around and the carbs were treated to new needles (from NRP), new emulsion tubes (from Factory Pro) and a full seal kit from LiteTek after an Ultrasonic bath. COP conversion, new loom connectors through out and sealed battery and happily fired up after the winter in the workshop, with no need for the Easy Start.
Happy days. Cheers for the clip position and mixture screw. Close to what I ended up setting it to anyway.

Good to know youre up and running


Pics ?