Ivan kit and revisit to cold starting

[NitramA]

Did you buy genuine Yamaha parts?  If not, all bets are off ...

I've had bad experiences in the past with aftermarket carb parts, particularly replacement float needle units.  Never had an OE needle/seat pair leak fuel regardless of age/mileage, though.  I suggest you refit the originals and check the float heights again.

On stock floats, the tang which touches the needle valve will be completely flat.  It's easy to see if the tang has been bent by someone previously messing with the float height.

I went with Yambits as I thought they would be better than the stuff you see on eBay for a couple of quid. Maybe I shouldn’t have....
I’ll refit the originals and see what it looks like.