Have you opened up the oil drain tube for the airbox and drained out the goo?

This may sound simple, but, if you are having the same problem with 2 different carbs check the fuel flow and throttle & cable & routing, Something may be hanging.

badwolf wrote on 01/17/18 at 09:35:02:

CV slide is vacuum activated, so I doubt it's cable related.
It acts like a stuck slide, sometimes a good bump will result in whoa nellie moment.
And removing the slide is difficult because it is... stuck.

On a positive note... I can pull and replace the carb in less than 30 minutes.   :'(

I swear by OLDFELLER's air cleaner and have used it for years. the problem with the breather hose is it discharges between the air filter and the carb and at a level almost even with the carb opening .It may be worth a try to drill through the box ,an insert a short nipple to carry it beyond and maybe below the filter ,allowing the gook to drop out and only oil fumes to be sucked back threw the filter,( with a short hose and small filter of the type used when removing the air box-there's room) keeping the slide cleaner. Of's filter is loaded with veg oil ,I don't believe oil fumes would hamper it's operation. My air box has two drain positions ,one with a hose (the section between the filter and carb)and one with a small cap that could be swapped( to drain the section on the inlet side of the filter.)

Had to double check myself, yep ,one facing the rear of the bike drains that section.

This may be objectionable to some here, but on every carb I have had that was a CV carb, I have faithfully used LUCAS gasoline additive (I buy it by the gallon from Summit Racing- lots cheaper!) as I use it in my auto and lawn mower.  It is used at a 400:1 ratio which is 3.2 oz per 10 gallons of gas so it lasts a long time.  

However, it has kept my carbs absolutely spotlessly clean - in all locations, AND it keeps all the moving parts lubricated.  Whenever I have taken them apart after I started using the gas additive, there was a slight slippery film on the slides and even up to the diaphragms.  I swear by it!  On the BMW's which have been notorious for having terrible BING carbs, after using the gas additive, I never ever had even one more problem with dirtiness or issues with slide failing to properly move.

FWIW,
Stripping two stroke carbs -you know what they are don't you - I always found them to be in pristine condition, I think because of the petroil. I have used a tiny drop of oil in various 4 stroke bikes thinking it would help the carb. My reservation is that it might foul the cylinder to some extent? It seems like a good idea? Gas seems to me to be a poor lubricant.

What's the consensus?