I too have a 78 390 WR..... for my sins ! It is very much an aquired taste. The handling is not like your usual Jap crossers. Mine still runs the std Husky fork yokes, which means it is not the fastest turning bike around. The only way I have found to get round a corner quick is to sit on the tank, turn, and when pointing in the right direction give it a handful. A set of billet yokes that reduce the angle would be better. Mine also suffers from an annoying top out "bang" when the forks extend. Not got around to looking at that yet.
I run the std Mikuni carb with the jetting as stated in the manual, however, I found it needed the next size up pilot jet to be just right.
Has yours still got the WR swingarm ? If so, this is shorter than the 78 CR arm. (I think it was from the 77 model) The shorter arm has the adjusters on the other side of the axle. The shorter arm is better for turning and enduro use, but makes it a little front end waving in the air for motocross.
Make sure the engine bolts are secure (they have a habit of coming loose) as this affects the earth for the Motoplat.
If you have the original brackets that hold the side number plates on...... look after them, as they are very hard to find.
If your engine is sweet, and your suspension is in good order and not too stiff, then you should have no problems. Just get out and practice on it to get used to the swedish handling !
Not much else to say really, other than the normal preparation bits we would all do before a meeting.
