Before you start working about plug chops ( which are quite useful)
You need to read up on carb jetting in genera, just like leak tests, compression tests, top end rebuilds, and mixing fuel, jetting is something you need to learn if you are gonna ride and maintain a two strokes. Jetting a carb is not that hard as far as how to make the adjustments / change jets, the difficult part is being able to sense if it is rich or lean and learning to think in terms of throttle position not rpm.
The good news is the stock carb is already on for the most part, if you go with the stock 32.5 pilot, 1 3/4 turns out on the air screw, 3rd or middle clip on the needle very little adjustment of the lower circuits should be needed. Typically about a 310 main jet for the Toomey with the airbox vented or lid removed, is pretty close. It can vary depending on temp, elevation, engine condition etc.
You need to read the jetting info in the carb section, it wouldn't hurt to do a google search for 2 stroke jetting as well.
Before you start you need
A fresh clean air filter, a box or two of plugs
Float height set to IIRC 21mm (see carb section )
Leak test results, if needs to be leak free or close to it or the task goes from tuning for best performance to trying to get enough fuel in it to keep it from dying a lean death. If your leaky, it needs fixed.
Main jets at least 3-5 sizes above and below where you expect to end up. Jetsrus or rockymountainatv are both places I have got jets from and had good experiences with. Get genuine Mikuni jets.
Other than the above (I know I am forgetting something important), your motor should be generally in good shape, fresh plug, fresh mix gas. And try to be somewhere where you have a nice long preferably uphill run, to do your plug chops and make passes at various throttle positions. I have found that 3rd or 4th gear, starting at a steady 1/8 throttle cruise, then going to the throttle position you wish to test and holding it until it revs however far it will go rpm wise, gives good results. For the lower ranges below half throttle I sometimes will ease off a bit then back to the test position or add a bit of throttle then back to the test position seems to give me a better idea of how its acting at and around that position.
Usually I deal with idle, 1/8 throttle or barely open, 1/4 which is a slow cruise, half (important for needle setting and a lot of people will chop here to verify), 3/4 which is where the needle and main jets switch over and WOT for setting main jet.
You can usually skip and do idle, half ,and WOT. Since with the stock carb you wont need to concern yourself with finding the right needle or slide cut out.
But I would go read up on jetting, leak tests, and setting the float, order my jets (or pick them up at the local Yamaha shop), then start looking into getting everything in good shape and ready for actually jetting when they arrive.
Enjoy ans sorry if its a rough read, I suck at English.
thanks alot!
