05 is the yr, with 3k miles on it....  just recently purchased this bike, and it runs amazing.... for roughly 10 mins.  Then is slowing starts to loose the ability to rev, i.e. looses power until it just stops running.  I have cleaned the carbs, so its not a carb issue... I have searched and searched and came up with signal generator, and have replaced it.  All other electronics checked out.  But havent checked them after it stalls out, which I will tomorrow.  So what are some ideas as to what is causing this?  I will start with unhooking the stator and rectofier so that I can isolate the problem a bit more..  Could a bad ground, or a bad battery cause this issue?  reason I ask is the person I bought the bike from was a shady fellow, and have found loose bolts here and there like it has had things tampered with....  Any help or advise would be appreciated, and hello to all in this forum

An electrical issue would generally not cause "slowing starts to loose the ability to rev, i.e. looses power until it just stops running". Electrical would be pretty much...running, then...off.

Does it start after it shuts off? Does it turn over?

Don't knock off carbs just because you cleaned em. They are probably the issue. Without knowing what the plugs look like, or if your fuel lines are running dry, or a number of other fuel related things, it's tough to answer. I would start by making sure the lines are running properly, and try running the bike on PRIME instead of ON or RES. After that, make sure the floats are set properly, make sure it's not running too rich. When my bike was rebuilt I had all kinds of fuel/air issues and at one point it would bog down and stall...it was getting too much fuel. What jets are in the carbs? Are they the proper ones?

I would bet it's in the carbs, almost guarantee.

Battery system charging? You sure your not low on fuel where it needs to be on reserve ? (basics just to rule out).

Side note, try riding it around set to reserve on the petcock.

Solaratov, it's not pertinent to this topic, but I disagree about the electrical issues being "on or off". I was out riding one time and thought I was running out of gas so I flipped it to reserve. Kept sputtering and popping, and I just happened to notice my fog light was extremely dim......come to find out, a bullet connector between my stator and R/R rattled loose. No charging system = bike was running off the battery alone.

But to the OP - I'm going with fuel starvation as well. Carb vent, gas tank vent, clogged fuel filter, etc.

When it cuts out will it start back up and run on ok prime? If so I am thinking a vacuum hose is installed wrong or pinched.

Big Rich - Good point. Battery could do it...I just usually lean towards believing the carbs go bad before electrical, especially when I hear they have been apart.

We just need more info really. If it at least tries to start after it cuts off, then it has to just be a mistake in re-assembling the fuel system.

Quote from: hergs on April 26, 2013, 09:20:58 PM
05 is the yr, with 3k miles on it....  just recently purchased this bike, and it runs amazing.... for roughly 10 mins.  Then is slowing starts to loose the ability to rev, i.e. looses power until it just stops running.  I have cleaned the carbs, so its not a carb issue... I have searched and searched and came up with signal generator, and have replaced it.  All other electronics checked out.  But havent checked them after it stalls out, which I will tomorrow.  So what are some ideas as to what is causing this?  I will start with unhooking the stator and rectofier so that I can isolate the problem a bit more..  Could a bad ground, or a bad battery cause this issue?  reason I ask is the person I bought the bike from was a shady fellow, and have found loose bolts here and there like it has had things tampered with....  Any help or advise would be appreciated, and hello to all in this forum

check your overflow lines, drain lines, from the carb. if they're plugged, you'll see similar symptoms.

run it on prime next time. when the symptom presents, immediately try draining the carb bowls. are the free flowing/fast, or trickle ? any jelly looking (water) material ?

pull the feed line at the carb, from the tank. is it free flowing ?

rap on the carbs lightly with a small screwddriver. if the floats are stuck, it may start and run well directly.

Quote from: hergs on April 26, 2013, 09:20:58 PM
05 is the yr, with 3k miles on it....  just recently purchased this bike, and it runs amazing.... for roughly 10 mins.  Then is slowing starts to loose the ability to rev, i.e. looses power until it just stops running.  I have cleaned the carbs, so its not a carb issue... I have searched and searched and came up with signal generator, and have replaced it.  All other electronics checked out.  But havent checked them after it stalls out, which I will tomorrow.  So what are some ideas as to what is causing this?  I will start with unhooking the stator and rectofier so that I can isolate the problem a bit more..  Could a bad ground, or a bad battery cause this issue?  reason I ask is the person I bought the bike from was a shady fellow, and have found loose bolts here and there like it has had things tampered with....  Any help or advise would be appreciated, and hello to all in this forum

The salient part of the diagnostic is the 10 minute period before it starts to gradually lose power.  Gradually losing power is how I tell to switch to reserve gas.  Looks like there is a partial fuel line or gas tap clog.  That's where I'd look first.

not to contradict any of you in a offensive way.  If you search electrical issues with the gs500, one of the main issues is the signal generator.....  the issue is that it would work fine for roughly ten mins, then one of the sides would quit firing properly, ultimately fouling out.... yet after it sits for 20 mins or so it would fire back up and run properly again for 10 mins or so..... that is the issues im having, so thats what i replaced first.....  so im assuming that something else is having this issue since this is the symptoms......  I have replaced the fuel lines, (yes have check if they are in right place), checked that there is gas, no clogs(cleaned the carbs and put in a fuel filter)  yes its the right filter facing the right way, put in clear lines so I know that its getting fuel, the floats are set right, have checked that also..... 

Did you open gas cap and try immediate restart after it died to see if it's a gas tank vent problem?  Based on your stopping after 10 minutes and waiting 20 to restart my mind zeroed in on the electronic ignition system too.  Never had that problem on bikes but had it on 2 cars back in 70's and 80's when electronic systems were new.  Turned out one was a bad module and the other a bad pickup.

just ran it for 10 mins with the rectifier unplugged to isolate problem a bit more....  its not the stator or recrtifier causing it....  will open tank and see if it will start it again...

Well looks like im pulling the carbs off once again.....  I put the battery in from my gsxr1000 (hence the name hergs) and fired it up without stator plugged in, the lights unplugged literally everything that didnt involve the bike running to rule out a ground somewhere, or bad ground.  It died again, well this time I turned off the fuel petcock and after a few seconds turning over it fired up.... well ultimately I kept it running for about 40 mins with the fuel on/off alternating method.....  so it is flooding itself out.... Thank you everyone for their advice, and i apologize for being a newb to this bike.....

Additional confirmation would be to check the plugs, figure which side or both? And then figure out why.  I'd be checking float height via 'U' shape bend with clear tube on the carb drains. The gas level should be equal to the gasket height.

- Bboy

do as gsjack suggested with the gas cap to check for a clogged fuel tank vent. do you have a timing light? if so when it dies and you try to restart. hook it up and see if you are getting spark. aka timing light flashing.
when it is running do you have 14 or so volts at the battery? this of course with the engine rpms up around 4k.
last question. are your valves adjusted?
engines need a few basic things to run. fuel,spark and compression. find out which one you are losing after 10 minutes.
fuel could be your carbs ( float height) or vacume petcock.
spark could be your ignition system or battery. is hasnt gone dead when it dies has it?
and compression. is a valve / valves sticking open once warmed up?