Had to get towed home today :icon_sad:

[Plan_W]

Hi, I'm a new rider this year.  I bought a 2007 GS500 as my starter bike as I'm 6'5" and I can't fit on anything smaller.  For the past 2 weeks I'm been commuting daily to work ~20 km each way, rain or shine.  Today on the way home the tach started dropping to zero, then coming back, dropping to zero coming back over and over.  The engine never died, but when the tach was at zero the bike had absolutely no power.  It was too dangerous to ride like that in rush hour traffic, so I had to get it towed home.  Any thoughts?  It's still under a powertrain warranty from the dealership that I bought it from used.  I'm going to give them a call tomorrow and see what they can to for me, but they're outside of the city and it would require another tow to get it there.  Anything obvious to check?  I've got the Haynes repair manual, but I'm new to bikes and I don't really know where to start with this one.

Thanks in advance.

[yamahonkawazuki]

was she making any odd noises? maybe it was losing fire or coils were weakening with heat? can you elaborate on what it was doing before, and during this episode? so I can figure out whre you could go from here?

[mustangGT90210]

Was it fuel starving? Did you try turning the petcock to prime? At least in my eyes, the tank looks like it has plenty of gas left even when it needs to be on reserve. Through me off for a bit. Start easy, work your way up!

[yamahonkawazuki]

over these two weeks, how often have you put petrol into your gs' tank?

[Plan_W]

Update - thanks for the replies so far.

I rode the bike yesterday for 20 km without replicating the problem.  I did clean the battery connections (they were dirty, but not too bad). I ran through all of the gears, various rpms, hard acceleration, underpowerered acceleration etc.

So I'm trying to think about what conditions were unique to friday's ride.  Thursday night was cool and raining.  I filled the gas tank just before putting the bike away for the night.  The bike sleeps in a cool garage.  Early friday morning I biked 20km to work (before the heat of the day).  The bike parking at work is in the direct sun all day long.  Friday was a hot sunny day.  Could the symptoms I described be the result of a full tank of gas expanding due to heat and overloading the fuel system?  When I rode it yesterday with no issues it had been stored in thr cool garage and the weather was cool.

[Steve146]

A similar condition happened to me.  Also an '07.  It turned out to be a kink in the fuel tank vent tube.  It was starving for gas but each time i stopped it gave it time to refill the float bowls so it seemed like nothing was wrong.

Straightened out  the vent tube, no problem.

[Plan_W]

Thanks Steve.  I'll take a look to see if that's the problem.