O.k., if you are going to run with the lid off and the peashooter out(wich is the smart thing to do) then Yamaha recomends taking the stock 158 MJ out and replacing it with a 165MJ for riding at 3000 feet and below. If you dont run with the lid off the box then you cant jet up to the 165, you will be way to rich and you will be fouling plugs and losing power. But if you have to run with the lid on and the peashooter out then install a 160 or the 162 jet and see wich one works better for your elevation. For the guy that is riding at 8000 feet + you would want to run the 160-162 jets and you would have to run with the lid off, so you better invest in a K&N and some out wear. As for the pilot jet, if you are doing your own jetting I wouldn't worry about it. All the pilot jet does is ap[ply gas to the machine when you let off the gas. I can tell you from experience that if you go to a 165 your idle will be fine. The only downside will be some backfiring, but to me backfiring is easier to put up with then pulling out the carb. You can do all your main jetting with the carb in place.

One thing to remember, the pilot jet is crucial on a two-stroke but not on a four stroke. If you are flying down the trail on a two-stroke and you let off the gas your piston instantly starts to get hot if your pilot jet is not big enough, that is how alot of 2-strokes seize up. Their gas is crucial for cooling while the four stroke cools more from oil lubrication from the crankcase, so it doesn't care if the pilot is too small, but if you have the time and money and you dont mind pulling the carb then you might as well put it in. The needle movements will help the back firing also and give you better throttle responce. Just remember that the main jet is by far the most important jet because it covers 3/4 to full throttle, this is the range when the piston is going to be the hottest, so if you get that right your good to go.

 

WFZWideopen. I agree with what you said I am just saying that if you are raising the needle that high your pilot is probably too small. So for the carb to be jetted correctly you should change the pilot. I havent gone there on mine yet but I will once I have it broke in Then I will post my results..

 

so what your saying about jetting is that if i take the baffle out and lid off that if i dont rejet the engine i will burn it up when im in on the main? i really didnt want to have to rejet the thing but im going to silver lake and i dont want to burn it up over there so im in michigan and i have no idea whats the elevation so i dont know where to jet it so can i leave it there and not burn it up or should i rejet? and if so what should i rejet it too?