I think the biggest thing Rain teaches you is to be smooth. Nothing breaks traction in the rain like snappy inputs. In the dry, you can get away with quick turn in or slamming the throttle down as the grip levels will forgive you. In the rain, if you turn the steering too quickly the front end will push and if you apply throttle too quickly off the corners, the rear will step out. Its like you have to slow everything down to go fast. You start turning in earlier at a slower rate to hold the grip. On exit, you put down just enough power to drive out of the corner with out sliding. These are all principles good drivers talk about in the dry. I imagine the affects those principles are merely exaggerated by the low grip conditions of the wet. I suspect Great Drivers have learned the to better read the limits of grip and hold their vehicles right up against those limits.
Racing in the rain with slicks really teaches you to be smooth, especially with a shifter kart!
I mean depending the track I think you are getting way ahead of yourself for 206. As I said in the other thread. You said you had 20 minutes. You’re not going to be changing clutch springs in 20 minutes along with everything else.
Im on a 219 chain and jump 2-5 teeth on the rear gear. Push the rear hubs in to as narrow as I can go. Put on the filter cover. Toss a foam pad in the bottom of the seat. Slap on some rains and send it. If you have more time then you can look at front end alignment changes pending how it felt in the first session.
I agree with Lindsay, if you only have 20 min, make sure you get the chassis settings he mentioned figured out. Widen the front, narrow the rear, sit on something to simulate a raised seat, and if you have time, change gear and go up a few teeth.
I disagree slightly with Greg regarding the driving aspects of rain. It isn’t necessarily all about smoothness, though you do have to have a very acute feeling for the grip limit. @Terence_Dove’s old lessons on rain driving from Karting1 is how I try to do it. Big input at the beginning of the corner, charge the corner, get the kart to jack, and then smoothly modulate all inputs through the corner to keep the kart from breaking free. I’ve posted this pic a dozen times on this forum, but it shows what I mean:
Really need to use your body weight in the rain.
Thank you all for help…
I think gear manners less than some other things. You will usually have enough power to spin tires in rain. More is not needed. I think equalizer comes mostly because the fast guy has brake, apex, and throttle point dialed in for dry track. In rain it changes lap by lap tending to bring the less consistent more on line with more consistent since everyone is not going to be consistent.
I’d say it depends on the track. With rain corner speeds are going to come down. Which means optimal rpm is going to be affected. This is in regards to 206. More horsepower classes I would agree it might not be as critical.
Ha Ha! Remember the Axle Thread…I don’t have a problem getting the kart to Jack in the Corners. My issue is too much inside wheel lift. Maybe that’s why I keep up better in the Rain. 
Thought it apropos.
Guys, thank for all good comments and hints - this is all so helpful. Appreciate all!
Reviving an old topic mostly because I don’t see my delema mentioned and tomorrow looks to be a wet raceday.
As I said tomorrow (Sunday) is our first race of the season and there is a 80% chance of rain. Aside from the changes mentioned what about driving line. I know it has been mentioned previously that changing your line is usually a good idea to stay off the rubber (preferred dry line), but our track is GREEN. They have had 2 practice days since winter so there is little rubber on the track. Sunday is going to also be cold upper 50’s, low 60’s, does line choice matter?
Yes. If there is no rubber laid down it might be possible to run a racing line. Part of rain racing is experimenting and hunting for the grip as the track constantly changes.
And it may vary corner to corner. You might be able to run the racing line in one corner but a more conventional rain line in another. Just need to experiment.
If it’s really wet don’t discount the areas that are bumpy and rough.
This is interesting. I have too little rain experience to comment but the thought resonates. Maybe why I am bad at wet.
Even if a track is relatively green (as far as rubber deposition is concerned), you also have to consider the condition of the actual asphalt or concrete on the racing line. The dry line can become polished smooth over time (relative to the rest of the track surface), so even if there is little or no rubber buildup on the racing line, in the wet there may still be more traction available on the road less traveled.
100% try and watch the fast guys in other classes this will expediate the learning curve of where to drive
If you can walk the track that’s a bonus. Abrasive surfaces are good, smooth not so much. Once you get on track, try lots of different lines and observe how the kart behaves. Use apex kerbs where it makes sense. By use I mean hammer 
Rain racing can be a lot of fun - when you’re confident in it… but that confidence normally comes with experience, so get out and do it as much as you can.
The reason confidence is important is that to really make the chassis work in tight corners in the wet, you have to aggressively attack the corner entry to get the kart to transfer weight and lift the inside rear. If you’re overly cautious on entry, you’ll struggle to transfer weight and the kart won’t want to rotate. Once the kart’s rotated, from that point, it’s then being patient enough to get the wheel pointed straight so you can get back on throttle.
Most spins in the wet don’t happen going into the corner, rather they tend to happen mid-corner to corner exit. And more often than not, it comes from people who are too cautious on entry, where the kart takes so long to rotate, that they lose patience, and jump back on throttle too early, and around they go.
Racing lines in the wet will vary even more by type of kart and class, than they do in the dry. For example, in a shifter, you’ll often see them running way inside of the normal racing line, and basically hooking the inside front over kerbs through a hairpin, whereas a momentum class like Briggs might find you running the outside edge of the track. No matter the class, you have to be willing to experiment a bit with lines to find where the grip is in the wet. Guys who’ve done dirt oval racing where they constantly search for grip tend to do alright in the wet.