Spark Plugs Fouled???

Don’t confuse the correct length and heat range of a plug with its regular/platinum/iridium construction. Iridium lasts longer - it is highly resistant to erosion as well as allowing a finer tip which enhances spark efficiency.

Starting problems as you describe are more likely down to old fuel that has lost its more volatile elements combined with cold and damp making fuel atomise less readily. The plugs will only foul if your injectors are way too rich (pretty unlikely) or you are burning oil...... which you would smell.

My working suspicion is you have a low mileage 12+ yr old bike that needs a good dose of Seafoam to flush through the entire fuel system. Now? Drop in some fuel stabiliser and agitate.

 

Maybe a clue is why somebody has chosen a hotter plug over book.
Is it, or has been, used for a load of short runs?

 

I’m not a fan of just starting the bike without giving it a run, maybe you don’t need better spark plugs, get it going and give it a good run to clear it out.

 

I just got a set of iridium sparked off eBay at £7.55 each, better than the standards at Halfrauds for over £10

Going in my mates FZS600 that was in storage for 15 years

Supposedly very good for easier starting and longevity

 

I had the same problem with a 2010 GSXR, it was purely down to just starting up and not taking it for a ride, never did it again without a run and no problem for the five years I owned it

 

Starting a cold engine either carb or fuel injection will just result in over rich air/fuel mix and if the engine doesn't get fully warm it will always foul the plugs to some degree, hotter plugs will help but may not be ideal once the engine is at WOT and full ignition advance, fitting iridium plugs wont help as they are just longer lasting and have no performance advantage as some seem to think.