Classic Fuel Starvation Trouble Shooting

[gilkeyb]

The carb vent tube kinks EXTREMELY easily.  I had the bike stall and run like hell for 10 minutes before I figured it out.  Make sure that there is enough slack, and if necessary go to your local FLAPS and get a hose connector to extend the hose.

By the way, FLAPS = Friendly Local Auto Parts Store

If mounted the wrong way or into the wind just right, it will cause your symptoms.  I'm not saying that it's 100% your problem, but it's worth a shot.

More info on "Crosswind Engine Stumble"  http://gstwins.com/gsboard/index.php?topic=60976.msg705248#msg705248

Well, Jestercinti, you're the winner.  If you ever find yourself in the Metro Detroit area, i'll owe you a beer!

I re-routed the carb vent over the airbox and behind the battery (between the battery box and the rear fender).  Took the bike for a spin and it runs like a dream.  Cruising at 65, 75, 85mph didn't notice even a single hitch in performance.  Just smooth sailing the whole time.  YEEEEEEEEEEESSSSSSSSSSSSSSSS!!!! (sorry, I had to get that out of my system).

I parked it and it smells the least bit like fuel, so I may be a little rich now.  My 3x1mm o-rings are probably closer to 2 shims than one.  But its close, and it runs! 

Thank you to everyone who weighed in and attempted to help me sort out the issue (bombsquard, jester, Bboy).  I knew it was going to be something simple that I missed, and low and behold I was right about one thing!  A slap on the wrist to remind me just how little I know about working on powertrains. 

Brian

[bombsquad83]

Congrats!  Really glad you got it sorted out!  Enjoy your bike now bud! 

From post #10 in this thread . Sorry, I had to toot my own horn a bit as they say. 

Also make sure that your carb breather tube is kept out of the wind.  It should terminate behind the airbox and be held there by one of those flexible clamps that is screwed un under the bottom left corner of the air filter. 

[gilkeyb]

Congrats!  Really glad you got it sorted out!  Enjoy your bike now bud! 

From post #10 in this thread . Sorry, I had to toot my own horn a bit as they say. 

Also make sure that your carb breather tube is kept out of the wind.  It should terminate behind the airbox and be held there by one of those flexible clamps that is screwed un under the bottom left corner of the air filter. 

You are absolutely right.  I could have solved this issue much sooner if I had just heeded that advice.  I do remember reading it, but for some reason I over looked it in my various trouble shooting steps. 

So, I owe you a cold one too.  Or a spin around the block on my awesome running 1990 GS500E

This actually couldn't come at a more perfect time.  My girlfriend and I have had a trip planned to Ontario to visit family and do some sport touring around the lakes north of Toronto.  I'll have to squeeze in some quick shake down cruises on the GS to work out fuel economy and road worthiness.  If all checks out, this trip just got a whole lot better since she won't have to ride pillion the 400 miles there

Brian

[jestercinti]

Glad you got that sorted out... 

My wife's uncle lives in Chesterfield, Township (Macomb County) so I may take you up on your officer at some point 

[BockinBboy]

Definately a BIG congrats. Such a relief for you I'm sure.   
... Another bright side is: You have the cleanest carbs on a 90 GS500 in this hemisphere! 

- Bboy

[gilkeyb]

Well, since confirming the bike was running last tuesday, i've managed to put almost 350 miles on my GS.  Mostly cruising around M-25 which follows the thumb of Michigan.  The one thing i didn't like was the bike became quite "chuggy" below 2500 RPMs in 5th or 6th.  I pulled the o-ring shim off my needle and that seems to have helped the situation slightly.  I'm sure this makes me just slightly on the lean side, but i'll take a slight drop in performance for a more steady low speed and slightly better fuel economy. 

The two fill ups i've done netted about 48mpg total, which seems a little on the low side?  Most of the riding was just steady cruising at 65mph.  Could anyone offer at about which point the bike hits reserve?  Is it around the 3 gallon mark?  Slightly more perhaps?

Thanks again to everyone for the help.  I look forward to taking this touring next week.  Its looking like we'll be doing ~1000 miles in 4 days

[bombsquad83]

I think an oring shim is probably a little much.  1 washer is less than 1 oring I'm sure, and I had really good performance with 1 washer and 125/40 jets.  You should really probably never be below 2500 rpm in 5th or 6th.  That's pretty much bogging the engine and you should just go to a lower gear.  At least in my experience.

[gilkeyb]

I think an oring shim is probably a little much.  1 washer is less than 1 oring I'm sure, and I had really good performance with 1 washer and 125/40 jets.  You should really probably never be below 2500 rpm in 5th or 6th.  That's pretty much bogging the engine and you should just go to a lower gear.  At least in my experience.

Agreed on all counts.  1 washer would probably be perfect.  When I get the chance i'll get a couple to put in.  As it was I had access to o-rings at work, which are probably more like 1.5 washers, so thats what I tried. 

And I definitely prefer to keep the engine up around 3500-4000 rpm.  But, it has taken a serious amount of convincing to talk my girlfriend out of lugging the bike down too much.  She has gotten rid of the habit for the most part, but I just wanted to make sure the bike wouldn't stumble too badly if it did drop down that low.  Shes been well briefed on all the quirks of the little 500

Brian