Recommendation for jetting USA 2003 Yamaha WR450F for high altitude
1 reply to this topic
Posted September 13, 2004 - 01:24 PM
I'm going to Circleville, Utah and then on to Bryce, Utah in a week and would like to get some recommendations for jetting a USA 2003 Yamaha WR450F for riding at what I have been told will be at 6,000-11,000 ft (call it 9,000 ft avg). The bike has the air baffle removed, gray wire cut and stock exhaust system with a GYT-R exhaust insert. The carburetor settings are factory stock, except the Main Jet(MJ) is #158 vs #150; the Pilot Jet (PJ) is #50 vs #45 and the Pilot Screw (PS) is 2 1/2 turns vs 1 3/4 turns. Note that I DO NOT have the James Dean mod and the stock Jet Needle (JN) and clip position are OBDUT-4. My feeling is that these settings, which work fine at 5,500 ft, will probably be all right. However, I am open to suggestions from those who have, "Been there done that".
Posted September 13, 2004 - 02:44 PM
You will be fine with 160 main, clip #4 on stock needle, 48 pilot, 72 starter jet, At higher altitude the temps drop and I find the bike jetting does not change as much as some people would like to think.