Last weekend I performed the throttle spring relocation procedure described numerous times herein on my 2004 YFZ 450. I also replaced the throttle assembly with one from a 400 EX. With the tors disconnected near the carb. it wouldn't start. I reconnected at that location and unplugged the tors from the Yamaha throttle assembly where it enters the wiring harness under the front plastic. It would start and idle erratically but would not run clean nor pull out without dying. We reconnected the Yamaha throttle assembly and tors and the problem went away. Our solution was to clip the tors wires before they enter the main wiring harness and wire them together. A brief five minute test ride showed that the quad ran perfectly and the throttle was much easier to use.
The quad has a full HMF exhaust with the rubber air sleve on top of the airbox removed. I jetted the quad last year with I believe a 165 main, a 58 pilot and a yzf 450 needle. The quad ran strong but would occassionally backfire on deceleration particularly when ran hard.
Today I raced a hare scramble in about 50 degree temperature. While warming up the quad I noticed that the fan was running when I shut off the quad after 3-4 minutes of idling. The quad ran great for the first seven miles then I noticed that the idle had gotten really high. Without warning the quad quit. After about ten minutes it restarted with the choke on but backfired horribly. It would not start or run without the choke on. It ran for about two minutes then quit again. I went through this several times before getting back to the pits.
Does anyone have a clue as what problem/problems I am experiencing? I believe the jetting is a little lean all around but I never experienced these problems till messing with the tors system. Several friends and I have plans to race an out of state hare scramble next weekend and I will be out of town most of this week so I have little time to try to diagnose and fix this problem. Please help!!!!
The quad has a full HMF exhaust with the rubber air sleve on top of the airbox removed. I jetted the quad last year with I believe a 165 main, a 58 pilot and a yzf 450 needle. The quad ran strong but would occassionally backfire on deceleration particularly when ran hard.
Today I raced a hare scramble in about 50 degree temperature. While warming up the quad I noticed that the fan was running when I shut off the quad after 3-4 minutes of idling. The quad ran great for the first seven miles then I noticed that the idle had gotten really high. Without warning the quad quit. After about ten minutes it restarted with the choke on but backfired horribly. It would not start or run without the choke on. It ran for about two minutes then quit again. I went through this several times before getting back to the pits.
Does anyone have a clue as what problem/problems I am experiencing? I believe the jetting is a little lean all around but I never experienced these problems till messing with the tors system. Several friends and I have plans to race an out of state hare scramble next weekend and I will be out of town most of this week so I have little time to try to diagnose and fix this problem. Please help!!!!