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Discussion Starter #1
I have a 98 900S with a very annoying problem. I bought it in the winter and managed to put several hundred miles on with no problems. It seemed a little coldblooded and I am pretty sure it's too rich (smells like gas), but seemed to have plenty of power. The bike is setup with Remus pipes and pods filters with no emissions stuff and no vent pods (carb vents open with no hoses). I've never really ridden it in warm weather.

A few days ago, on the very first really nice day of the season, I was riding in stop and go city traffic and I noticed it getting REALLY warm between my legs. Next thing I know, it sputtered and died on throttle, like the fuel had been cut off. I let it sit a minute and limped it home using the choke to keep it lit up under partial throttle. I checked the oil level and it had plenty. After it cooled off, it ran fine. I assumed it was some sort of blockage in the fuel filter, so I replaced that with a clear type to monitor the flow. After a bit of riding, it did it AGAIN. I tried riding around a bit with the gas cap loose, and that didn't seem to help. I did notice that after it died, fuel flooded into the filter when the tank was lifted. It started and ran fine for a minute, then tried to die again within a minute. I checked the fuel pump vacuum line, and it was clear.

Any ideas?
 

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What do you mean by 'carb vents open with no hoses'?
Emissions being gone, I would make sure the tank is vented underneath and not capped off or something...though riding with an open gas cap would have fixed that.
Then I would check for vacuum leaks. You can do that by running it at idle and spraying all the hoses and intake boots with starter fluid, if the idle rises you've got leaks.
Next would run it out of gas, drain the carbs, then fill it with a fresh tank and some fuel additive...I've had good luck with gumout. get the stuff with water remover in it, and put new spark plugs in it.
Not knowing what it is, I would try that stuff first because you can do it all for about $12.
After that I would think maybe fuel pump on its way out...
Good luck....
 

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Discussion Starter #3
vapor lock

After thinking awhile on the symptoms, I'm pretty sure it's vapor lock that's going on here. This just started when the weather warmed 30+ degrees in the northeast which means I probably still have "winter" gas in the tank, and it looks like my fuel line is basically lying on the cylinder head, which is probably making the fuel boil. Going to ziptie line to the frame and possibly insulate.

Anyone have any suggestions to fight fuel heating?
 
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