frustrated...need more help

[importracer689]

hey guys,
okay since the stupid stp incident, i just tagged/insured the bike today so i decided to take it for a few mile ride. i rode about 10 miles then it f%&ked up (wont idle, makes like 1/4 the power it should, wont rev right, basically sounds like it is either out of gas or running on shitty old gas) so i limped it back to a gas station a mile down the road, by keeping it down like 2 gears more than normal. There, i checked the battery cables, the spark plugs, which came out clean, drained 3 gallions of gas out of it, put almost 4 gallons of 87 in it, cranked it up, all seemed well, so i drove it about 5 or 6 miles down the road and back, then it did it again, so i limped it home and its sitting outside now. any ideas?
i tried putting it on prime which didnt help, i dont understand???
if i go out in the morning, or in a few hours, it will crank right up and run fine for awhile?
what???

[Egaeus]

Sounds like fuel starvation.  From the sould of your symptoms, fuel isn't getting to the carburetors fast enough.  Check your lines and petcocks for obstructions, and inspect the screen filter inside the tank (attached to the tank petcock). 

Also try running it on PRI.  The vacuum diaphragm could be shot. 

Is there a fuel filter on it?

[importracer689]

Hey man,
, there is shitloads of gas coming out if i yank the line off the petcock, and if i switch it to prime or reserve it runs out fine too. there isnt  a fuel filter on it. so i would have to pull the petcock off the tank in order to check that out? i just went out and tried it now after sitting for ahwile and it still didnt do shaZam!? i guess ill go yank the tank and check out the screen in there, i didnt know it had one, that coud be it, since it sat for awhile?
any other ideas?

[importracer689]

alright, pulled the tank (for the umpteenth time), pulled the tank petcock out, it was fine, not a chunk of crap on it,
so i checked the air filter, its fine, then put the tank back on. this time i tried switching the lines going onto the tank petcock. maybe i reversed them las time? would that make a difference?
thanks,
mark

[Egaeus]

if i switch it to prime or reserve it runs out fine too.

It's not supposed to come out of the frame petcock in RES or ON if the engine's not running.  Only in PRI should it flow freely.  I'm guessing you have a bad diaphragm on your frame petcock, or someone's modified it. 

If you look on both the tank and frame petcock, there is a mark for reserve and on (R and O).  Match them up.  The long line coming out of the tank is reserve. 

[hmmmnz]

to me it sounds like one of the coils is overheating and failing, but if one of the plugs isnt wet you can probly ignore that.
good luck 

[importracer689]

okay, im thinking that it is a coil problem too, but neither of the plugs comes out wet, and neither of them even get warm to the touch, even after a few miles of riding. i took it by a shop today and he said to pull the carbs and clean them, which i guess im going to do. dammit..i was hoping to not have to do that..ever...dammit damn damn...anyway, ill try that.
thanks guys, ill keep ya posted

[Egaeus]

I was hoping to not have to do that..ever...

Boy, did you ever get the wrong motorcycle....

I might just be up that way in a few weeks on the way to Deal's Gap, so if you don't get it running, I might be able to stop by and look at it.  But don't bet on that, because it all depends on the weather. 

[ducati_nolan]

Pretty much whenever the thing isn't running right, the first thing you should do is clean the carbs, set the float height, and make sure it's getting enough fuel. Resist the temptation to fiddle with jetting changes at this time too, if it was working fine before, get it working again before you try to "improve" it.

That being said, it dose sound like an ignition problem, possibly a coil. Get some new plugs and gap them, they're cheap so eliminate that possiblity first. When it starts running poorly try pulling one of the plug wires off. If it still runs about the same, then that coil may be bad. If it dies, put the wire back on, start it up and try the other plug. If the results are about the same with both plugs, it's probally not the coils, but it may be a problem with the ignition pickup or black box. Also check the spark, by turning it over with the spark plug held against the engine and looking for the blue flame.
Hope this helps 

[3imo]

put almost 4 gallons of 87 in it,

I don't want to start another Octane thread, but In my bikes (Both GS500's)  87 octane gas causes the exact same symptoms you mentioned.

If I were you I would rebuild your carbs anyway.

#1 you have to learn sometime (it IS a GS500)
#2 It is too easy.

Then try some Premium gas (I always use Chevron 93)

I MAy not be right but from my experience even mixing 87 octane into my tank fucks up the performance.

Just my two cents.

[3imo]

if i go out in the morning, or in a few hours, it will crank right up and run fine for awhile?
what???

Although this symptom reminds me of when I had a bad coil.  Could also be a ground issue.