I have installed a FMF silencer and a ProDesign filter system. My elevation is 5000 feet. Does anyone have any ideas about the correct jetting? Is it fairly simple to correct or should I have the dealer make the necessary adjustments. I would like to learn how but I don't want to screw it up!!!

 

I have contacted FMF about my pipe and rejetting and not received any word. I met a guy riding that had put one on that day and called FMF and they told him it did not need to be rejetted. The local Yamaha mechanic said to open the idle mixture 1/2 to 3/4 turn on the left carb.

 

rwalker, with just the silencer it may not need rejeted with the filter system and no air box lid you will need to rejet also with a full system you will need to go bigger on the jets to. Not sure what the jet specs are but FMF probably wouldnt be any help being that your running the filter system you might want to try big gun or CTracing for jetting specs because I know Ct has there raptor jet specs for a pipe and a filter so good luck and post back and let everyone know if ther was any big power gains with the silencer and filter system!

 

Because of your altitude, you might not need to change the jetting significantly. Maybe just move the 145 over to where the 140 is, then put in a 150. Check your spark plug before you make the jetting changes so you have something to compare to.
As far as difficulty, it's not too hard, but you do have to take off all the front plastic and remove the gas tank (turn the valve off before you do) You can just rotate the carbs and leave some of the hoses connected.
When you connect the carbs back to the air box, put a lot of pressure from the airbox pushing toward the carbs. I've heard reports from others that the carbs can blow off. The extra pressure can only help. One thing I ran into was that I had the airbox tweeked, so the lid didn't fit back on until I loosened one of the screws to let the box square up.

 

I went to the dunes this last weekend to test my stock Raptor with the jets changed to a leaner mix. The altitude is about 4000 ft. I changed from the 140/145 main jets to a 135/140 setup. It ran better than it did with the stock setup. Not a big difference, but enough to notice that I was pulling higher RPMs. The plug looked good and I wasn't too lean.

I also took some advice from a fellow Raptor owner I met down there and I pulled out the baffle. I did some testing before and after by high-marking on a sand hill. With the baffle removed, I got about 15 feet higher on the mountain before I had to turn out.

The baffle made a bigger difference than the jets.