I've been noticing that recently if I slow down suddenly from about 70mph by pulling in the clutch, and letting the rpms drop like a rock the bike will TOTALLY STALL.  :x

If I slow down by going through the gears and decelerate the bike will idle normally. I thought that it wasn't warmed up long enough, so I rode for an hour, experimented with letting the rpms drop from a high speed, and the same thing happened!!!  :x

I have almost 10000 miles on it, and i've done all the regular scheduled maintenance. So what's going on? Do the carbs need to be synched or cleaned or something?

Not too long ago someone theorized that during a high-speed stop the fuel sloshed to the front of the float bowls.  It doesn't seem like this would be a problem unless your float height is too low.

I have had similar experiences (bike dies when stopping from speed with a plenty warm engine) but I usually found that my choke lever was accidentally pulled back a little bit.  Maybe check for full extension of the choke plunger at the carbs?

i had this issue before i rebuilt my carbs and made the floats alittle on the high side. then it went away

Thanks Kerry. I checked the choke and it is fully forward as far as it can go. I think it started happening after I installed the suburban handlebar, which really pushes the cables around. Where and how do I locate the choke plunger at the carbs?

Quote from: Blueknyti had this issue before i rebuilt my carbs and made the floats alittle on the high side. then it went away

Would simply cleaning them help as well?

OK if it is carb related... MIne was doing the same thing... and the problem was floats were too high ... yes ... 2 mm high. I set them back and it cleared up... But choke and plug pull right when it stalls willbe the key.
Cool.
Srinath.

Heres a possibility: First, does the GS500 carbs use a real choke (actual butterfly that closes off much of the throat of the carb when the choke is applied), or an "enrichening circuit"( which is another circuit in the carb that actually supplies extra raw gas when you apply it-usually by pulling a knob)?
   If the bike has an enrichening circuit, then they are usually in the fdront of the carb.If the knob has a bad oring on it, then I have read that when you brake hard, the fuel rushes forward in the carb, and the bad oring lets it temperarily overfuel the carb stalling the bike.I had this problem on a 1982 Suzuki SP500 dual sport four stroke thumper I once had.Of course if the GS has a real choke, then I am wrong on this-since I don't own a GS500, I/m not sure which it may use.
   Just a thought.

   Jon Neet

Quote from: cucamongaI think it started happening after I installed the suburban handlebar, which really pushes the cables around.

Yep, that could take out just enough slack to keep your choke slightly ON all the time. (Not SURE about that, of course.  :dunno: You'll have to dig deeper....)

Quote from: cucamongaWhere and how do I locate the choke plunger at the carbs?

You've got an '04, right?  So let's use pictures of Manjul's bike.  It's an '02 ... I think.  Anyway, it's the post-2000 style and should match your F.

The first picture was taken from the rear.  The choke cable is the thin one on the left, with the curving metal sheath where it attaches in front of the left carb.


The second picture shows the long, thin, oddly-shaped brass plate that's attached to the actual choke plungers.  The cable moves the plate and the plate moves the individual plungers.


In the second picture the choke cable is detached from the brass plate.  Since the plate is spring-loaded, this will be its right-most position (as seen from the REAR) ... the "all the way OFF" position.  Let's say that you reattach the cable and push the choke lever all the way forward.  If the brass plate ends up anywhere to the left of this "all the way OFF" position (as seen from the REAR) then you have less than no slack in the cable.

But never fear!  It looks like the designers have accounted for that problem.  See the large Phiillips-head screws that connect the brass plate to the carb assembly?  I bet you could loosen those a bit and push the plate TOWARDS the cable and then retighten them.

Does anyone care to try it?

Quote from: Birdmovedoes the GS500 carbs use a real choke (actual butterfly that closes off much of the throat of the carb when the choke is applied), or an "enrichening circuit"( which is another circuit in the carb that actually supplies extra raw gas when you apply it-usually by pulling a knob)?

It's the latter - an "enrichening circuit".

So I could be right if it indeed does have an enrichening circuit.An exploded view of the carbs should show, if you look at the knob and shaft that you pull to do the cold start, an oring.I think usually these shafts are screwed in-maybe it has backed out a little?This shouldn't be a problem on a brand new GS though, as orings get hard and brake down over time-unless there may be a split in it.

   Jon Neet

Great pics & info! I think I'll start by trying to adjust the choke lever and try and manually push the choke all the way over. Maybe i can disconnect the choke lever from the handlebar (?) just so that the cable won't feel pressure to slightly open due to the handlebar.

If that doesn't work i'll look at the float heights or bring it in to the dealer for them to check out.

Birdmove,

In this diagram from the Ron Ayers website, item 33 is the choke plunger (one for each carb) and item 47 is the brass plate (mentioned with the photos above) that moves both of the plungers.

Does that help?

Quote
In the second picture the choke cable is detached from the brass plate.  Since the plate is spring-loaded, this will be its right-most position (as seen from the REAR) ... the "all the way OFF" position.  Let's say that you reattach the cable and push the choke lever all the way forward.  If the brass plate ends up anywhere to the left of this "all the way OFF" position (as seen from the REAR) then you have less than no slack in the cable.

But never fear!  It looks like the designers have accounted for that problem.  See the large Phiillips-head screws that connect the brass plate to the carb assembly?  I bet you could loosen those a bit and push the plate TOWARDS the cable and then retighten them.

Kerry, is the following description correct? The choke lever, when opened, pulls the choke open, then the choke lever essentially 'pushes' (or uses the springloaded effect) to push it all the way closed.

If my handlebar makes the choke lever sit lower than before, wouldn't it stand to reason that the scrunched position of the cable would make it more likely to 'push' the choke plate closed all the way?

Just trying to use some deductive reasoning before I get my hands dirty...

Quote from: cucamongaKerry, is the following description correct? The choke lever, when opened, pulls the choke open, then the choke lever essentially 'pushes' (or uses the springloaded effect) to push it all the way closed.

Let me restate what you said.

When you pull on the choke lever the choke cable is pulled upward through the cable housing.  This causes the brass plate to pull the choke plungers to the left (as you sit on the bike).  This action compresses 3 springs: the one at the lower end of the choke cable, and two associated with the plungers (see item 36 in the Ron Ayers diagram linked to in my previous message).

I don't pretend to understand the actual mechanism of the choke circuit; just that it actually adds fuel (enrichens) rather than restricting air flow like a "real" choke.

When you push the choke lever forward the cable retracts because of 4 different forces: the 3 springs just mentioned, and the (wimpy) stiffness of the cable itself.  Resistance to the cable's movement comes mainly from friction between the cable and its sheath.  While you can almost ALWAYS pull the choke on, it's not uncommon for the cable to get "hung up" in the sheath because of gunk or lack of oil or a bend in the cable.  Those little springs aren't nearly as strong as YOU are, and they need all the help they can get.  When the cable gets really dirty, pushing the lever forward only results in the cable bunching up -- at the handgrip or elsewhere.

Quote from: cucamongaIf my handlebar makes the choke lever sit lower than before, wouldn't it stand to reason that the scrunched position of the cable would make it more likely to 'push' the choke plate closed all the way?

Yeah, that would make sense.  As long as you didn't introduce any tighter curves in the cable than it had before....

Quote from: cucamongaJust trying to use some deductive reasoning before I get my hands dirty...

Understood!  But you ARE going to get them dirty anyway, right?  "The more you know the better it gets!"  :mrgreen:

Hey cucamonga, you always pass on the right?  Niiice!!! lol...

Quote from: DomHey cucamonga, you always pass on the right?  Niiice!!! lol...

Yeah, that's the mirror (in my avatar) I usually see when I split the carpool and #1 lane. It's also the mirror on the cars i've dinged a couple of times. Dang minivans!

In the diagram, 33=plunger;34=starter valve;, and 37= o-ring.So that oring could be bad or split.It happened to my SP500.When I gave it heavy braking, it would slosh gas into that "enrichening" circuit, and flood, or overfuel and stall the engine.

   jon neet

Quote from: Kerry
When you push the choke lever forward the cable retracts because of 4 different forces: the 3 springs just mentioned, and the (wimpy) stiffness of the cable itself.  Resistance to the cable's movement comes mainly from friction between the cable and its sheath.  While you can almost ALWAYS pull the choke on, it's not uncommon for the cable to get "hung up" in the sheath because of gunk or lack of oil or a bend in the cable.  Those little springs aren't nearly as strong as YOU are, and they need all the help they can get.  When the cable gets really dirty, pushing the lever forward only results in the cable bunching up -- at the handgrip or elsewhere.

Yeah, that would make sense.  As long as you didn't introduce any tighter curves in the cable than it had before....

Understood. I can see how bunching could be an issue, since there's an extra pressure the springs have to overcome. I'll definitely be getting my hands dirty now...