GS doesn't want to run today

[cogito]

I am on a 1996 GS500e that still has stock exhaust, stock jets, and a K&N filter in the stock box.

I have been having the issue of "bogging" down due to fuel delivery.  I tried a few different filters and found one that seemed to fix the problem.  I also replaced all of the fuel hoses, drained my tank, cleaned the tank's petcock screen, and cleaned my K&N.  The bike ran like it should even at 95+ for over 10 minutes and I rode it for days.

So last night I get my new fork seals b/c the old ones pooped out on me.  After replacing the seals I rode around the block to test and everything was great.

This morning I wanted to know how the new seals really felt so I left for class about and hour and a half early.  Just outside of town on the "long route" to school my bike decided to die just after a firm acceleration.  I sat out there for an hour or so and every few minutes it would run for a bit and since I had no other way home, I would ride till it died and wait till it ran again.  I eventually made it close to home where I just walked it the last 1/4 mile.

My clear fuel filter showed me that it was recieving plenty of fuel, checked the oil level one it cooled off and all seemed well.  Next I put the plug wire next to the plug and cranked it to see that I was getting spark.  So I figure the problem has got to be a carb issue.  Once I got home I pulled the carbs and cleaned everything out but it wasn't really dirty because I keep that thing clean.  I also noticed that one of my plugs was not as tight as it should be, couldn't remove by hand but pretty close.  So I pulled the plugs and used a brush on them.

Now she is all back together and she doesn't want to crank up.  The starter turns and it runs for a few seconds with plenty of throttle given but then it dies.

Tomorrow I will be getting new plugs to see if that fixes the issue but I don't think it will b/c it ran fine till this morning.  My dad suggested that the exhaust valves may not be opening all the way but he doesn't really know too much about engines.  There was only one thing I was unsure of when I re-assembled the carb.  For some reason I didn't pay attention when I pulled the needles out and couldn't remember if the shim goes onto the needle from below or above.  Logically it seemed that they would go on from below so that the needle would sit up higher. 

Needless to say I am stuck without anymore ideas accept for plugs.  Any help or ideas on what to check would be greatly appreciated.  One last thing, its hot here again, already in the 90's here in Texas, thought maybee that might have something to do with it???

[Egaeus]

I know you don't want to hear this, but it sounds like a fuel problem.  It could possibly be sticking float valves, though it wouldn't make sense for both of them to stick at the same time.  It sounds more like a restriction in the fuel delivery system.  Does it act differently if you put it on res?  How about pri?  The symptoms sound to me like there's just a trickle of fuel going to your carbs, the float bowls will eventually fill up, then you run it, they empty, it dies.  Since you replaced all of the fuel lines and the filter recently, then perhaps it's your petcock?

Edit:  If you're talking about washers used to adjust the needle valve, then you're right.  They go on the bottom to lift it up.  I put mine between the bottom ring and the C-clip (parts 4 and 9 on the carb fiche) and it works fine and keeps me from losing them.

[cogito]

Thanks for the response Egaeus, its greatly appreciated.

I absolutely agree that it must be a fuel restriction issue.  I spoke to a friend who works at a shop in town and he thinks that it might be float height.  I got it to run again but only with the throttle at least half way. 

It does not act any differently on res, pri, or on.  I have noticed that after some time it likes to run, as you say probably after the float bowls fill up.  Fuel delivery up to the fuel filter is ideal, in fact the best I have had it since I purchased my bike.  When I took it appart the float valve looked fine but that does not mean it is working. 

I plan on taking the cabs apart again tomorrow so that I can just ensure that I put everything back together correctly.  Other than the jets what would restrict flow once the fuel arrives at the carb?

[Mandres]

what kind of fuel filter did you use?  Maybe it has become dirty/clogged over the course of the last week and is restricting flow?

-M

[cogito]

Hey Mandres thanks for the response.

I feel a bit dumb for not checking that already but I will bypass it in the morning and find out real quick.

[3imo]

have you ruled out your electrical system?   I had similar issues and it turn out to be a bad coil.

just a suggestion.  There is a how-to thread on a VERY easy quick check. 

Try it out.  might save you some time.

[Egaeus]

Hmmm.... If you're going to bypass the fuel filter, you might also try bypassing the frame-mounted petcock if the fuel filter isn't the issue.  It is vacuum actuated, so it might be malfunctioning.  I have heard of this on the board, but haven't experienced it myself, so it's more of a WAG, and not definitive. 

Checking the float height is very easy.  Much easier than the impossible-to-measure-accurately Clymer manual's method.  Go here

[cogito]

Thanks for all the responses guys.   

I just bypassed the filter and the same issue occured runs for a few and dies.

I left the petcock on pri after I pulled the filter and the fuel flowed from the petcock quite well.  I believe that if I try to check the float height while the fuel is being restricted then my float level will not be correct anyways.

So the fuel is making it to the carb as well as I could ever hope for.  The restriction must be in the carb itself if this is a fuel issue.  After my only class today I will check the coils.  Not the most likely problem but a simple test can rule it out.

I remembered one more thing too, when I cleaned the plugs yesterday, they were kinda black, while normally they are kinda grey.  I thought that this might suggest that it was running rich but that just doesn't fit into the equation.

[3imo]

A Note on the coils-

remember you may have a spark, but that doesn't mean the coil is operating 100%.

I had just enough spark to keep both cylinders running after warm up.  It was an open in the line from the coil to the plug, causing a loss of power before the plug.

The only reason I bring it up is because I rebuilt my carbs twice on the advise that it was "running too rich". Advise I got on this forum.
A simple check would have saved me the time and trouble.

good luck

[cogito]

OK guys, I checked the coils as suggested http://gstwins.com/gsboard/index.php?topic=19546.0 .  They seem to be fine and function well during the few minutes that my bike runs.  I rode around the block while it was running one of the times and the power, that is the engine, surged over and over till it died and I walked it home. 

I took the carb apart again and cleaned it even better, took a long wire through every hole.  Still the same issue, it runs for a few and then dies.

I have decided that I think I may still be putting the needles in incorrectly.  I have designed two excellent pieces of artwork to illustrate my question.

Should the spring that loads from the top of the carb compress onto just the plastic piece that you drop the needle into or should there be a washer on the top of the needle that is big enough for the spring to hit and force the needle down?  The image on the left is how I have it set up now and the image on the right would allow the spring to push the needle down as well.

   

On the second cleaning I noticed that on one of the carbs, the o-ring that seals the float assembly in place looked a little too old for my liking.  It made a good seal after I lubed it up a little so I wondered if this could be my problem.  It does not seem likely at all but I thought that I would mention it.  I will run up to the auto store later and see if they can help me out. 

A buddy of my father who races cars says that the smaller jet inside may be adjustable and I should try loosening it by one full rotation.  Is the smaller jet adjustable on this carb???

[Mandres]

nice artwork    Your needle is installed wrong.  The plastic 'spring perch' goes on the top of the needle.  The c-clip is below that and the nylon washer/spacer is below that.  The image on the right is the correct way.

-M

[cogito]

Alright, with a little help from everyone and of course Mandres I have now got the needle in correctly and I also have a running GS.  But that is about all I can say yet. 

When I rev the rpms up they take a while to come back down and there is almost no power when I try to ride.

I drilled out the brass caps during this process and they were at the stock 2+ turns out when I first touched them.  I figured i'd fiddle with the air mix and now I have it at 3 turns out and it is still running like this.  I have tried 1 1/2 - 3 turns out and it reacts about the same for each.  I remember a post describing how to adjust based on this exactly but I cannot find it now.  I will continue searching, in the meantime perhaps someone else could offer another suggestion.

[cogito]

Ahhhh hah, the last installation of the carb yielded a clamp that was tightened while covering the wrong part of the airbox boot.  It is now fixed and running quite well.  Good power going through the neighborhood but I still have one small issue that I can probably fix by fiddling with the fuel air mix.

The rpms are still not dropping down after a rev as fast as they should, or at least as fast as they used too.  I am unsure if this would mean rich or lean. 

Other than this my baby is running great and I can finally go out tonight and test out my new fork seals and spacers out in Texas Hill Country.  Texas Hill Country is great, canyons, curves, lakes, and Devil's Backbone!!! 

Thanks soo much too all of you that have helped, it is greatly appreciated.

-Craig

[cogito]

Final note:

I tinkered and now shes great, put the timing back to advanced (put it back to normal for troubleshooting) pulled the screw out just a bit, rode for 30min and I couldn't be happier.

[Mandres]

right on!  The Hill Country is great riding, I actually bought my GS from a guy who lives in Canyon Lake about halfway between Austin and San Antonio.  Interesting guy, he runs an Alpaca farm.

-M

[scratch]

The rpms are still not dropping down after a rev as fast as they should, or at least as fast as they used too.  I am unsure if this would mean rich or lean. 

Lean (for future reference)

Glad you got it running.

[cogito]

Yes, Devil's Backbone runs right into Canyon Lake, I am out there all the time riding.  Thanks again for all the help.

[Egaeus]

The jets are not adjustable.