TOPIC:

 Hi Gents
looking for some help with my carbs, i seem to be getting a flooding issue on a couple of plugs on start up, i have tried adjusting the mixture screws using a gunsens colour tune but i can turn the screw in completely and the flame still stays yellow any ideas
many thanks

Not enough info to even begin with a solution.
Typically, if you can turn the pilot screw IN (closed)  all the way with no affect to RPM - there's a blockage in that idle circuit.
Flooding?  What is the clue to this.
Float level?   A quick (typical) check isn't good enough.  Let that bowl sit for 1 - 2 minutes and ensure the level doesn't creep up.  If it does then the float needle isn't shutting off the fuel flow completely.  Combine this with a "weeping" tank shut off valve (Petcock) and flooding will occur.  A flooded bowl will expel fuel from the high speed needle.
My experience with the Gunson's Color Tune .is that it will show yellow on the lean and rich side.
Are the spark plugs arching when shorted to the block?  If not then it's a bad plug, a bad lead or a bad coil. 
I can go on and on but won't......at this point.
. 
 
 

Thanks Scotch
on start up i am getting fouled plugs on numbers 4 and 6 with the exhausts being cool, i have new plugs in on all cylinders and the other 4 seem fine, i have had the plug out and tested them and i have a strong spark on the affected cylinders so hence i thought it would be good to start with checking the mixture screws but i freely admit to have little experience on carbs, it had previously been running fine on all six

Thanks Paul.  Being that 4 & 6 are cold might eliminate ignition issues as this involves 2 carbs.  So;  going back to the Pilot screws, I'm willing to bet it's some form of blockage in those 2 idle circuits.  With the engine running use a finger to block the Idle Mixing Air Port on the Filter side.  (Top ones).  This should cause a rich mixture for the idle circuit. If there's a change in RPM and a smoother idle then you've proved there's a partial blockage. If there's no change then assume the idle circuit is completely blocked. Either way -  they need a thorough cleaning.

Keeping it simple for now ! 

Couldn't resist linking this post of idle circuit problems and the idle vent ports being blocked with larvae eggs. 

How Clean is Clean? Mystery Blockage. 5 years 8 months ago

This may be of help:Two weeks ago I went for a 262 Kilo. ride. No problems. Parked the bike for 1 week. The following weekend I started the bike to warm it up for another ride. Didn't sound right ! Pulled each spark-plug lead and determined #3 and #4 weren't firing. Checked the ballast resistor and the ignition pulser coils (Ignition triggers). OK. Tested the Ignitor per the manual - OK. Started the bike again and still not right. This time it was #1 and #2 that weren't firing. Cleaned the male terminals on both plug ends of the Ignitor. Started it again and all was Good !