Hi guys, as title...
I'm still having issues getting my NC21 starting. Managed to get it firing on 2 cylinders but not all four. Have a good spark on each cylinder and have good compression.
I damaged the original NC21 carbs whilst cleaning them so went on ebay and got some other ones. The new ones are 32mm ones (mine were 30mm) and they have the curved 'cup' as appose to the square on my previous carbs..

Basically, am I having problems starting because I have NC24 carbs attached?

Cheers.

dont think so.

carb rubbers are differnet so you will need to fit 32mm carb rubbers from an nc24/nc30 of course but if your carbs are on properly then all that might need tuning is the jetting.

slow circuits are the same so fuelling at idle / starting wont have any noticable different.

either new carbs are knackered or not setup right / connected on the bike properly or you have ignition trouble.

Ok thanks mate. I'm fairly sure the carbs are set up right, float heights at 6.8mm, and pilot screw out 2 turns. must admit though I am using the 30mm rubbers as they do fit nice and snug.
I'll order some new rubbers though and see if that helps.

opened all the drain screws to make sure you got fuel in all 4 carbs?

Yes mate definitely getting fuel through each one of them. The plugs are wet with fuel when you take them out. They are brand new plugs also.
I just find it hard to believe that it wont fire up properly when air, fuel and a spark is present...even if the mixture is way out?

wet plugs means its flooding.

tried drying them off and starting it again?

i dont see how your mixture is way out unless you did something with the carbs?

stock nc24 carbs will work ok...