NGK spark plug problems

[bluemouse1006]

Just bought some iridium NGK plugs for my CB750 K5 to try and help with the cold start probs
Anyone had any experiences with these are they compatable ?
Seems my bike runs very badly and floods with these in and when I put the normal ones in it runs a lot better !
These plugs are 4x more expensive as well !!

Any feed back much appreciated

Will be sending them back if they are no good for the old gal

Cheers

Amos 

[hairygit]

What plugs are you trying?

[bluemouse1006]

NGK IRIDIUM IX SPARK PLUGS
Same number on plug but has an extra x in the number ??

[totty]

I run iridium plugs in my 550 without any problems, but no notable benefit either.

They make a big difference in my monkey bike, it runs a large carb to maximise top end and needs to run a rich idle, iridium plugs seem resistant to fauling.

[Bryanj]

I would suspect something not quite right in the ignition circuit if standards run better, possibly carb tune