depends how long the fuel has been left in the carb ,if left for long periods the fuel evaporates & leaves a sort of varnish behind in the main jets , idle jets , & high speed jets depending wot carb you have in this   case  strip  it down &soak it over night & get a thin steel wire to clean the varnish out that has gone hard in the jets as it blocks the tiny little fuel holes in the jets  then blast with compressed air 

Here is a link to the procedure some other members use.  All I'm after are some opinions on chemicals that are up to the task.

http://www.fishing.net.nz/asp_forums/decarbs_topic37202.html

Hey mate, I've run seafoam through my engine, seems to do the job, but can't say I've "needed" to do it as such, have just done it as part of the maintenance. All I did was get a container of the stuff, put it in a spray bottle, then while motor at a fast idle, spray into the intakes until motor chokes out (Mine didn't quite conk out completely, maybe because it's a v6) And then wait about 20 minutes before firing it up again and giving it a decent burst of throttle under load. I have heard of people leaving it overnight etc, and running it through a tote tank, but for me personally I didn't see the need. (when I stripped motor down to do gaskets etc, there was minimal carbon build up)

Oh yeah, sorry, I may have forgotten to mention that part.. smokes like all hell! If the neighbours don't call the fire service I'll be surprised! :P

a decarb is very important on any 2 stroke this done on a regular basis will prevent the rings car-boning up in the ring grooves when this starts to happen & the rings are not moving freely & get stuck in the ring grooves this is when piston shave starts taking place & it wont be long before you end up with major damages

asked my outboard guru about de carb,why you are running 98 arent you

riga wrote: Anyone know where to buy this stuff?

from a marine business/boatshop, the best stuff is called Evinrude Engine Tuner or Mercury Power tune

When we did the old 2 stroke. it was put out of gear, revved up a little then added the carb cleaner, it wanted to die so upped the throttle a bit and man did it smoke like hell...ran it for a 5 minutes and stopped and left it for 2 hours, came back and started it up and it smoked again, but settled down took it for a spin and all good :)