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Discussion Starter #1
My bike will start right up if it has been sitting overnight. Once I ride it for a while and turn it off, it won't turn start up again until I let it sit and cool off. It will crank so it can't be electrical, at least I don't think so. possibly something to do with the carbs? Anyone run into this problem before? :headscratch
 

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Discussion Starter #3
I can compression start it and it'll run fine once it's started. Wouldn't the fuel pump effect it while it's running?
 

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I can compression start it and it'll run fine once it's started. Wouldn't the fuel pump effect it while it's running?
Im not understanding you correctly i guess. So after it gets hot and you shut it off, it will start up by push starting but not by the starter button??
 

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I have a friend with a 97 9r doing the same thing. His is carb issues though. What if you try to start the bike with the throttle open about half? Does it start?
 

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Discussion Starter #6
Correct kb. It'll crank with the start button, but won't turn over unless I give it an hour to cool off. And kitty, I tried all different throttle positions and choke settings to no avail.
 

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On cars there is a sensor on the first cylinder that measures the cylinders position. If that sensor starts breaking down, it causes the issues you are having. I think it's called a TDP sensor (Top Dead Point). I'm not sure if bikes have this same sensor, but if it does then I'm fairly certain this is the problem. Does it also start if you leave it say for 15 minutes after having ridden it?


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1. Just because it cranks over when hot, doesn't mean all electrical problems can be ruled out. It might crank over hot, but whether it has spark is a question worth asking.

2. Your bike ever have the valves adjusted? Valves get tight with engine use, and eventually they'll lose all clearance with the cams and be held open slightly... ie:hard hot starting gets worse until it finally won't start hot at all. Another symptom of this could be the engine taking longer to warm up in the morning

3. Could be vapor lock...
 

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After a bit of searching it would appear that your bike does indeed have a TDC (Top Dead Center) sensor. It's also sometimes known as a CAS (Crank Angle Sensor). This sensor is probably dying. Replacing it shouldn't be too expensive, they tend to cost around 90 euro's in cars.
 

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Next time you have this problem, try and open the gas cap and see if it persists.
 

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My 7r had hot starting issues but it wasn't too bad. I checked the valve clearances and found most of them were tight. I rectified this and ballanced the carbs at the same time. I have not had this problem since.
 

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something that might be way off base, but i had a similar problem in an old truck of mine. my final diagnosis was that i had replaced my exhaust with a different kind, i wont go into details, but, the problem with it not starting while hot was that the exhaust was heating up my starter, and I'm assuming the gears in the starter were expanding, therefore not allowing the starter to engage until it had cooled down enough to allow the starter to work properly!!! hope this helps!
 
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