I found out last year that I am only getting 51 miles to a tank of gas (appr. 10 gals) on the trails in MI and am guessing the carbs need to be adjusted properly. I bought the sled used 2-3 years ago and dont know if the previous owner re-jetted the carbs or not. My daughter was on a 98 Arctic Cat Panther 550 Dlx LC following behind me. And when I ran out of gas, the Panther still had a hair under a half a tank. Both were filled up at the same time and both went the same miles. I can smell that the Yamaha exhaust is richer then the Panthers.
So I finally tore into the carbs today. According to the manual, I am supposed to have a main jet size of 156.3. and instead I have main jet size 157.5, which is 1 size bigger. and the jet needle clip is in position 3, which is where it should be. Surely just 1 size bigger jet wont cause me to get 5 mpg will it? I checked the air adjustment screws and they are 1.25 turns out and the pilot jet is a 52.5. WOuld you reccommend me to put a 1 size smaller jet(153. in to increase my mpg, or just the reccommended size(156.3), or stay with what I have? or maybe just move the eclip on the needle jet? Oh and I snowmobile between 600 - 2000ft.
I just got done replacing all the steering sissor bushings, collars, and nylon washers, and smeared them all down with grease inside and out before assembling to prolong life. And I installed new plastic skis also. The rear skid and gear case was gone over last year to make sure all is well there. Greased all the bogie wheel bearings, replaced if needed. jack shaft bearings and track drive bearings greased or replaced. I have done it all to make sure the sled doesnt break down on me any time soon. new track last year also.
The sled has 4xxx miles on it, engine runs great besides running rich. I only put a couple hundred miles a year on it each year, seeing how Indiana doesnt keep snow on the ground much anymore.
So all thats needed now is to increase my fuel mileage and its ready to go to WI next month.