'97 Johnson venom 225. Going to be de-carbing the outboard in the next little bit. Last time I used the BRP stuff and the supplied nozzle spraying through the carb throats. Is there any good reason to use the adapter that allows you to attach the can directly to the Schrader valve? 

Actually, I think that adapter is so you can do DFI motors since their fuel doesn't go through the motor like carb motors do.

That makes sense. I wasn't sure. Previous owner was the one who mentioned using the Schrader on the primer circuit for decarb. I'm not sure that he actually ever did it though.  

Through the throats worked fine just was a little messy. Well a lot messy. The can would slow down, but not stop spraying when I let go of the button. I had that crap everywhere by the time I was done. 

On a V6, I always have a second can handy.  I get about half the can in it, then using two cans at once in two carburetors, I start loading it up and quickly jumping between carbs until I can stall the motor with it.  Then I let it sit over night.  Neighbors might not be very happy but motor is.   Then I start it up the next day, p***ing the neighbors off again.  and spray the rest of the cleaner in.  Then I take it to the lake and run it WOT for at least five minutes. 

I forgot to mention, I put an old set of plugs in before I start unless I'm planning on installing a new set.  After that long WOT run, I put my good/new plugs back in and save the old set until next time.   I have had problems with it fouling the plugs, that's why I don't use good plugs.

10-4. Thanks!  If I remember right I never was able to kill it with one can. I'll do the two can deal this year. 

Is it important to get the nozzle past the slide or is sufficient to just spray at the cutaway?

I've never been able to stall one just using one can. It gets hard sometimes with two.

If they have the straw thing in them, I don't use it, I've already fed one through an engine that came off while spraying, figured I didn't want to try for a second one.  I take the air silencer completely off so I can get it up close and personal with the carbs.

I'll be ditching the tube then. That would be my luck. It's a wonder it didn't happen to me last time. 

If you have a set of wire bits (numbered 60-80), you can drill the hole in the spray tip out a little and it helps a whole lot when trying to get enough into them to stall the motor.