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Runs till heats up-DIES-restarts after cool down HELP!!!

11K views 2 replies 3 participants last post by  YFZ450NF150 
#1 ·
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!!!!
 
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#2 ·
this sounds like what happened to me. i had to drive it with the choke on because when ever i went to push the throttle it would die. people were telling me it was the tors and to grease it. im not sure how i could do that but thats what people were telling me it was sticking and thats what was stopping me
 
#3 ·
whats your location and alt.? a 168 sounds lean for a main....if you have the stock yfz needle...what clip is it on? a 58 pilot is way too rich....a 45 and 48 are popular...i run a 45 with my mods....dont forget that you have an idle screw "black knob" and air/fuel mixture screw.....

Now as far as tor goes...i just cut and spliced the wires together near the throttle when i switched over to the honda throttle. no problems here

i would check my jetting for one...if it only runs with the choke..that tells me its not enough gas...lean....

check your throttle cable...it could be binding as well...

check your idle...you might have to turn it up....

remember jet up for cold and jet down for hot weather.....

this is a performance quad...jetting is always changing...depends on where u ride.
 
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