poor idle and died at 80km

[Courtice_GS500]

Hello everybody

I'm new to the forum and hope you guys can help.
I just picked up an 02 gs500 43000km.

Changed the oil, checked the plugs (they look like the bike might be running lean but i will get to that), cleaned the chain, just your basic maintenance when getting a new bike.

So here are the issues I'm encountering:

Fire the bike up with full choke on and a little throttle and it will start. Let it warm up for a couple minutes and start to turn the choke off and it dies.
Start it again, leave the choke on for longer and it warms up but the idle is bouncing between 800 and 1100 RPMs.
I took it for a 15 minute ride or so to get a feel for the bike and bring it back home.
Since the idle was bouncing I checked for vacuum leaks all over with wd-40 and found none.

So i took it out the next day, same issue with the idle but it rode fine for 2 30km trips. Checked the idle and it was bang on at 1100 rpms with a slight bounce.

Today I took it out for a ride same starting idle issues however something worse happened. I was riding along at 80km, 4th gear if that matters maybe 5.5k rpm and the bike completely lost all power. The tach hung up at 3000 rpm. I pulled the clutch in and tried downshifting and it died completely. I managed to get it home with that happening one more time.

Got it home, stripped it down. Check all the lines, gas/vacuum and vent which were all good, no blockages or kinks. Disassembled the carbs, blew out all the jets and reassembled. All o-rings were present and in good shape, as well as the airbox and carb boots.

Two things were found during this process.

1:The airfilter is real dirty
2:The choke cable is not moving freely

I found a new air filter at a local shop, it was a K&N su-.... (cant recall the number). The filter paperwork states that it can't be used without a restriction cap which I or the shop don't have so i returned it.

So after that here's the million dollar question:

Would a dirty air filter cause that many problems?
( Just a note, I tried to clean the old filter but it is still giving me the horrible idle)

I'm no expert of bikes by any means but if a bike was running lean like the plugs are showing wouldn't a restricted (ie dirty) filter help by increasing the fuel in the fuel to air mixture?

I appreciate any help or suggestions you might have.

[Kerry]

Hello everybody

Hey yourself!  Welcome.

I found a new air filter at a local shop, it was a K&N su-.... (cant recall the number). The filter paperwork states that it can't be used without a restriction cap which I or the shop don't have so i returned it.

Was it an SU-5589?  [My filter with that model number] came with a restrictor ring.  But that was, gee, 10+ years ago?

if a bike was running lean like the plugs are showing wouldn't a restricted (ie dirty) filter help by increasing the fuel in the fuel to air mixture?

Yes.  In fact, a "blocked" air filter can cause carbon build up on the plugs from the imcompletely-burnt fuel.  (See [THIS CHART].)  So, not sure how to fully explain your lean condition....

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It sounds like a fuel delivery problem to me.  You didn't mention whether you tried the PRI setting on the frame-mounted fuel selector. (?)

On my long trip back East last year, my '99 experienced what sounds like the same issue a couple times a day.  (Complete power loss, died when I pulled in the clutch, etc.)  It got to where I could tell it was coming, so I would pull in the clutch, let it die, turn off the key, pull over into the emergency lane (still going at highway speeds) wait about 20 seconds, turn the key back on, fire 'er back up, merge left and keep going.  (Not recommended for new riders or congested traffic!!)

Bubbles in the fuel line?  Restricted fuel flow?  Not sure.  Besides a good carb cleaning, I plan to look at alternatives to the frame-mounted fuel selector ... and to give the in-tank filter a good inspection / cleaning.

[adidasguy]

One problem we have seen here in Seattle is dirty frame petcock.

Here's the easy way it can get gummed up: you never use reserve for a long long time. The reserve fuel line has collected lots of crap and sludge. The first time you go to PRI or RES, all that sludge now goes into the frame petcock and even into the carbs.

One way I prevent that is to use the reserve every couple months. Usually just after filling up and for the mile or two to get home. That's enough to get fresh fuel into the line.

Now as for replacing the frame vacuum petcock with something else? No reason to. Anything else can sludge up after a while fron dirty gas and if the reserve is not used to keep that like clean.

You can remove the metal clip and clean out the frame petcock. I've personally seen 3 that were full of crap and caused fuel starvation. After cleaning, they were good as new.

Think about cleaning out all the fuel lines. Check the in-tank fuel screen. It may need cleaning. Drain the tank and clean out any sludge that has collected there. If there is stuff in the bottom inch of fuel, it will clog things up when you switch to reserve or prime. (Reserve and prime take fuel from the same reserve line out of the tank).

[Kerry]

Here's the easy way it can get gummed up: you never use reserve for a long long time. The reserve fuel line has collected lots of crap and sludge. The first time you go to PRI or RES, all that sludge now goes into the frame petcock and even into the carbs.

One way I prevent that is to use the reserve every couple months.

Good point!  In my case, I've had the selector in the PRIme position for some time, but that doesn't guarantee anything.

as for replacing the frame vacuum petcock with something else? No reason to.  [...] You can remove the metal clip and clean out the frame petcock. I've personally seen 3 that were full of crap and caused fuel starvation. After cleaning, they were good as new.

Yep, I think this is my next step.  In 50K miles I've never ventured into the frame-mounted selector.  Who knows what I'll find in there?

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Speaking of bubbles in the line, I was looking at the pre-'01 fuel hose routing diagram just now ...



... and noticed that the connections to the frame-mounted selector are actually (if the drawing is accurate) somewhat higher than the lower "T" connection between the carbs.

I'm not saying that it would be easy to get bubbles in the line ... maybe from a faulty vacuum seal and leaky fuel selector diaphragm? ... but if it happened, where would they go?  Up to the selector connection(s), right?  Where they could cause a temporary "halt in the proceedings"?

I'm wondering what it would take to lower the selector switch a little bit. 


EDIT: Of course, routing bubbles up to the carbs may not be the best idea either.    Just for grins, I'm going to try running  a hose straight from the REServe outlet on the tank-mounted petcock to the lower "T" between the carbs.  Or, maybe I can figure out a way to get this old brainstorm to work while keeping the entire fuel flow going "downhill"....

Code Select Expand


    ______________
   |               \
    \     FUEL       \
      \     TANK       \
        \ ______________|
                 R  O
                 E  N
                 S  |       T-Connector
                 |  +------  <----->  ----- To lower T-Connector between carbs
                 |              |
                 |              v
                 |
                 |              |
                 +-------+------+
                         |
                    Aux. Petcock



Sample T-connector for joining the RES and ON hoses:




Possible auxiliary petcock?

[Courtice_GS500]

I did check all if the gas lines for dirt/kinks when I tore it down when I got home.
I did not check the petcock but I will tonight.

I tried throwing it to reserve thinking I was running out of gas but to no avail.
It was hard to start up after it died but eventually it did and I got home with the petcock set to "ON".

That was the number for the k & n filter but it didn't seem to have the restriction ring in the package and the guys at the bike shop had no idea what I was talking about. I'm trying to track down an OEM filter currently.

[BockinBboy]

Just a thought, could be way off base but I figure I'll mention it... You said you thought choke cable might be sticking a little? Now mine doesn't stick, but if I accidentally leave it partially choked  ... once the bike is fully warmed up, I get erratic idle.  Now if I take off, bike seems fine for some time, but after awhile with choke partially on, the bike wanted to stall out if I let off the throttle.  It's happened to me twice, and I got all worried, but then I realized choke wasn't all the way off.  Pushed it the rest of the way up, and all was well.



- Bboy

[Calpantera]

Just a thought, could be way off base but I figure I'll mention it... You said you thought choke cable might be sticking a little? Now mine doesn't stick, but if I accidentally leave it partially choked  ... once the bike is fully warmed up, I get erratic idle.  Now if I take off, bike seems fine for some time, but after awhile with choke partially on, the bike wanted to stall out if I let off the throttle.  It's happened to me twice, and I got all worried, but then I realized choke wasn't all the way off.  Pushed it the rest of the way up, and all was well.



- Bboy

Oh ya good call. Free up the choke sliders and cable and see how it goes. You can always just remove the cable and make sure the choke sliders are all the way in and try it out.

[Courtice_GS500]

Will do.

New choke cable is on order.
The slide are moving freely, I check the whole choke assembly during my carb teardown.

New air filter is going in tonight and the petcock is nice and clean.
Fingers crossed since this was suppose to be my hop on and ride bike with no issues...lol... I should know better by now 

[Courtice_GS500]

Also this is probably a noob question but I will ask it anyways.

What is the proper start up procedure for the 02' gs500?

Right now I have it in neutral, choke on and a little throttle at the start to keep it from dying.
I keep the choke on for a couple of minutes and give it a little throttle.

After I turn the choke off the rpms tank to 500. Sometimes I can keep it from stalling with throttle or choke back on.

Even after waiting 5-10 minutes with choke on the bike doesn't idle above 1000 rpm.
That being said after I ride the idle is at 1100-1200.

Since my plugs are showing lean an I just put a new air filter in I'm lost here.

Is this normal? My 89' Katana would warm up in 30 seconds easy.

[Courtice_GS500]

Ran the bike tonight with a clean fuel chicken and new air filter.
It ran well once it was warm and I had no loss of power or any such shaZam!.

However the idle is still crap. Full choke on at start up and it has a hard time getting above 1000 rpms. Once I rode for a bit it was fine with no stalling.

Can I run my first couple of km's with the choke on or am I going to be fouling plugs?

[Kerry]

Sounds like things are looking up a little!   

Can I run my first couple of km's with the choke on or am I going to be fouling plugs?

I do it all the time, especially in the winter.  An alternative (if the bike will run without the "choke") is to reach down between the carbs and dial the idle up a little.  That won't affect things while you're riding like the "choke" will, and if it ends up too high after a while, it's easy to reach down and tweak it again at a stop light, etc.

[Courtice_GS500]

I will give that a try however I'm not to keen on fiddling with my idle screw while on the road.

I've read in the forms and the wiki that the gs500 is notorious for running lean and that they take forever to warm up.

Last night during my ride it was sluggish until I got her warmed up then everything seemed to be fine. After the ride I adjusted my idle up a bit to 1200-1250 to see If that helps.

I'm thinking now that summer is coming and I'm running lean that overheating might become an issue.

I have an all stock set up.
Stock filter (brand new)
Stock exhaust
Stock jets

Now the PO put the bike down and dinged up the pipe so I was thinking about getting a new stock pipe, however with the bike running lean im thinking I might need to rejet.

If that's the case should I go aftermarket pipe and jet up or for the mean time jet up and keep the stock pipe?

Also who should I be talking to about jetting up to get a richer mixture with a stock set up.

Bikes an 02' just I case your late to the thread.