Stuck wide open

[mikesmith]

I went for a 65 mile ride today, it was 116 degrees and 40% humidity.A little hot,on the last mile and a half back my bike felt like it was running lean so I rode with the choke on to limp back because I was so hot and tired I just wanted to get to my truck.At a quarter mile to go my bike ran stuck wide open,so I killed it,I could hear the slide move so I started it and it started wide open.After I shut it off and looked I realized it had blown the water pump seal(no coolant in the radiator,milky trans fluid.And I had just changed the tranny oil)So I walked back,when I got home I pulled the carb and the slide moves freely,Im wondering if it ran wide open on its own because of an air leak?Is it possible with the throttle closed to run wide open?It doesnt to me,but Ill have to look at it tomorrow and see what I find.

[Biggreenmonster]

Wow Mike thats unreal.Maybe an airleak was leaning the mix out enough for a strong high rpm idle.Hate to hear the seal go and water log the tranny.I would like to know for shure myself what happened.I am a mechanic,but no superstar factory tech....just fix all my buddies bikes and such.Maybe someone else had this happen....hope the top end is ok.

[JBKX]

MY 86 KX500 WENT WIDE OPEN WHILE I WAS WARMING IT UP ON THE STAND AFTER WRENCHING ON IT.  THE THROTTLE WAS CLOSED ON IT ALSO.  THE ONLY THING I COULD FIGURE WAS THAT IT MIGHT OF HAD A HOT SPOT DUE TO TRAPPED AIR IN THE COOLING SYSTEM THAT CREATED A LEAN CONDITION.  EITHER THAT OR THE THROTTLE CABLE BOUND UP LONG ENOUGH TO LEAN IT OUT WITHOUT A LOAD ON THE MOTOR.  IT HASN'T HAPPENED SINCE.  I'VE CHECKED FOR AIR LEAKS AND HAVE NONE.  I'D LIKE TO KNOW WHAT THE CAUSE WAS INSTEAD OF SPECULATING.

[Sharc]

Maybe it felt lean because without coolant it was overheating, then your choke loaded up the bottom end with fuel...?

[mikesmith]

I checked for an air leak but didnt find one.There was no coolant left,it was all in the tranny.I replaced the water pump seal and bearings,but I couldnt get the drive gear out with out using a drift and tapping it out with the bearings.To put it back together I put the bearings in the freezer,heated the gear and it still was tight,but it fits and turns smoothly.Im waiting for a gasket before I can run it, still Im wondering about it running wide open.The TV news said it was 116 degrees but the news paper wrote a reading of 119,so maybe with the high air temps and like Sharc wrote the no coolant and choke on,but where did the air come from?It doesnt add up.

[mikesmith]

I checked for an air leak but didnt find one.There was no coolant left,it was all in the tranny.I replaced the water pump seal and bearings,but I couldnt get the drive gear out with out using a drift and tapping it out with the bearings.To put it back together I put the bearings in the freezer,heated the gear and it still was tight,but it fits and turns smoothly.Im waiting for a gasket before I can run it, still Im wondering about it running wide open.The TV news said it was 116 degrees but the news paper wrote a reading of 119,so maybe with the high air temps and like Sharc wrote the no coolant and choke on,but where did the air come from?It doesnt add up.