Yes, I'm still having issues with my GS...  

The bike has what acts like a fuel starvation issue on the highway. I saw many threads about it, so I ran it in prime on the way home last night, but the issue still happened ( though the bike did only have about a gallon of gas left in the tank )

I filled it up last night, but have not been able to see if it still bogs down when trying to maintain highway speeds.

Friend thinks maybe the coils ( one or both ) are not working hard enough and that is why I get the stumbling/surging ( as even when the problem happens, occasionally it'll surge as if it were working properly, but only for a very small amount of time -ie 2seconds if that )

The other issue is the oil light ( which I mentioned off hand at one point or another ).  It's always on unless the rpms are above 2k.  Someone mentioned to check the sending unit ( which I have no idea how to ) or maybe faulty wiring...  If it were faulty wiring, or a bad sending unit, I'd think it'd be less consistent than it is now and could this cause high emissions if it's low oil pressure at idle???



What other things could cause the highway issues or the oil light?  :dunno:

I had a similiar problem with bogging- After I rejetted and put the full system exhaust on I would surge- especially at freeway speeds but more specifcally when I had wide open throttle runs (then I'd surge at 9000 rpms in any gear).  I had to take a larger diameter fuel line and run it as directly from the tank to the carbs.

Also,  People have mentioned similiar problems when their valves are out of spec (too tight, I believe)

Quote from: Hi-TI had a similiar problem with bogging- After I rejetted and put the full system exhaust on I would surge- especially at freeway speeds but more specifcally when I had wide open throttle runs (then I'd surge at 9000 rpms in any gear).  I had to take a larger diameter fuel line and run it as directly from the tank to the carbs.

Also,  People have mentioned similiar problems when their valves are out of spec (too tight, I believe)

Valves are in spec, already did that.

The re-routing straight to the carbs eliminates the petcock problems most people seem to have at highway speeds.

What year is your bike?

Quote from: mp183What year is your bike?

Sorry, more info about the bike.

1989 Suzuki GS500 - 17k Miles
 Possibly sat for a year or two.

I have :
 Checked the valves ( Fixed 1 )
 Rebuilt carbs
 Replaced air filter, fuel filters, fuel lines, and spark plugs
 Changed oil
 POR-15'd the tank

Shameless bump.... :|

Don't mind me... nothing to see here folks.

you mentioned that you redid the fuel lines, but did you try bypassing the petcock altogether?? Even though the problem still exists while your on PRI doesn't necessarily eliminate the petcock.  Only other thing I could think would be to check the shutoff valve under the tank, maybe its not fully on???

i had that problem......i fixed it by adding 1 more (2 total) washers under each carb needle and turning the air/fuel mix screws to less than 3 turns out, so right now it's about 2 1/2

Actually, on my way to work today, I ran it on prime with a full tank. I did not notice the stumbling and bogging down it would normally do on the freeway.

I have not tried bypassing the petcock completely yet.

Any thoughts on the oil light? Just a note I've noticed over the past few days, the longer the bike has been running, the higher the RPMs have to be to keep the oil light off.

Put an oil pressure guage on it to see if the light is malfunctioning or if the oil pressure in your bike is bad... BTW the spring on the filter... between the filter and housing probably deserves a check... as does the spring inside the filter.
Cool.
Srinath.

I don't think anyone mentioned this yet, did you check the vac lines?
That could be a problem even on pri, especially if your tank is low.  :dunno:

Well, It did fine to and from lunch as well on prime.

Regarding the vacuum lines, there's only one, and that was replaced as well.

Srinath : What could be wrong with the springs? And spring inside what filter?

Ok, so I bypassed the frame petcock and hooked the reserve line straight to the carb..

The bike was able to maintain 80mph across town w/o stumbling ( freeway ), however it was not able to maintain much higher speeds.

So two questions...

1. The reserve line had an inline filter on it. Could the combination of both the tank filter ( which I plan on replacing, just in case ) and the inline cause it not to maintain higher speeds?

2. The pingel petcock. Does this replace the frame petcock or the tank petcock? Does anyone know the part numbers? As far as I can tell currently, even the tank petcock doesn't flow enough fuel ( btw, I'm using 5/16" lines )

how does one go about cleaning/replacing the in-tank filter?? I might try that too.

Quote from: TheMasterRat1. [...]Could the combination of both the tank filter ( which I plan on replacing, just in case ) and the inline cause it not to maintain higher speeds?

Hmmm.  It might cause it not to maintain higher speeds, but you should be able to reach them at least.  :dunno:

Care to check your float height again?  (He says as he ducks and runs for the nearest fire escape.)

Actually, I've come up with a new "outside chance" possibility.  I wonder if your vent hose is partially blocked?  You know, the one that goes from the upper T-connection between the carbs to the open air behind the battery box....  After thinking about how that hose affects the system, I've arrived at the following hypothesis. (Fine - I've arrived at the following "guess" then. )

How does the fuel get mixed with air before going to the cylinders?  It gets sucked up from the float bowl through the jets, right?  OK, but the physicists among us know that things don't really get

sucked; they get PUSHED.  What pushes them?  The pressure behind them, if you will.

So, each carb has a venturi where a vacuum is formed by air (from the airbox) zipping across an opening at speed.  (Or something like that.)  That vacuum does the "sucking", but what does the corresponding "pushing"?

I say it's the atmospheric pressure applied to both carburetors via that seemingly useless hose.  You've heard the saying that "Nature abhors a vacuum"?  So when a reduction in air pressure is formed at the venturi, air "rushes" in through that hose, pushes down on the fuel in the float bowl, and shoots it up through the jets.

Does that make sense, or am I out in left field again?

My point here is that if the "useless hose" is blocked up, no air (or not enough air) can get through to do the pushing, and so the fuel comes up through the jets somewhat reluctantly - if at all.[/list:u]
In the same vein, I'd like to hear from someone that has separated the carbs from each other.  How likely is it that either of the T-connectors ... and/or the straight pieces connected to them ... are gummed up, dirty, or otherwise blocked?  And what about the inner passages that must exist in the carbs, between where those pieces connect and the float bowls?

So many questions ... so little energy.     (I'm talking about ME folks!)

Quote from: TheMasterRat2. The pingel petcock. Does this replace the frame petcock or the tank petcock? Does anyone know the part numbers?

It replaces the tank petcock.

For some GOOD STUFF, go to the Racer's Corner / Racing the Suzuki GS 500E page.  Then either click on the Installing the Pingel petcock link, or scroll down until you come across the How's Your Petcock? section.

Part numbers are included just before the PICTURES!  

Quote from: BadBatzMaruhow does one go about cleaning/replacing the in-tank filter??

Maybe GRU can field this one, since he took the photos on my Fuel Hose Routing page.

How did he get that filter out of there?  :dunno:  I always assumed that it fit through the hole in the tank, but looking at the "Installing the Pingel Petcock" pictures (see the link in my previous post) makes that seem impossible.

Anyway, once you figure out a way to get at the filter I would think that a good soak in carb cleaner (or ... gulp ... brake cleaner?) would do the job.

Can anyone confirm or deny?

One thing I do know:  there's no separate part number for the filter screen on the Ron Ayers parts fiche diagram.  But that doesn't prove anything....

Quote from: KerryHmmm.  It might cause it not to maintain higher speeds, but you should be able to reach them at least.  :dunno:

The bike will reach them, but will not maintain them. I had it at 95, but not for long before it bogged down.

Quote from: Kerry
Care to check your float height again?  (He says as he ducks and runs for the nearest fire escape.)

*chases kerry down the fire escape guns blazing*  :guns:  :guns:

Just kidding, might not be a bad idea... But seems slim chance.

Quote from: Kerry
Actually, I've come up with a new "outside chance" possibility.  I wonder if your vent hose is partially blocked?  You know, the one that goes from the upper T-connection between the carbs to the open air behind the battery box....  After thinking about how that hose affects the system, I've arrived at the following hypothesis.

Actually Kerry, that upper T junction is completely missing from my carb assembly... Always has been since I've had the bike :dunno:

Thanks for the Pingel links. I may replace the tank petcock with one.

Quote from: TheMasterRatActually Kerry, that upper T junction is completely missing from my carb assembly... Always has been since I've had the bike :dunno:

Hmmm.  Interesting....