Bike dies on stop

[ac_nvmax]

Hello everyone,

My '95 GS500 has a small but annoying problem. If I start the bike up it kicks on instantly - great! - and then revs normal at 1000-1500rpms (when the bikes hot it goes to 1600rpms ish which is normal).

I have found a really annoying problem. If I slow down and stop the bike will try to rev at just 500rpms, and depending on whether it is hot or cold will die. It then takes four turns of the starter motor before the thing will start again.

The only solution I have found so far is to rev it hard once before it gets to less than <1000rpms, then it tends to sit normally at 1,500rpms again.

Its absolutely annoying because it tends to stall just as i stop and need to start again on a busy roundabout.

Carbs just been synced. Running 33bhp kit (official suzuki not tcp kit), which I'll take off given the chance. Throttle revs freely and without problems upto redline.

Max speed = ~90mph
Acceleration = Appears normal and smooth.
Clutch = is not sticking.


Ideas???  

[Pkaaso]

Are you aware of the idle adjusting knob under the carbs?  It's a knurled knob just between the carbs under them.  Reach in with your right hand.

It's normal for the idle to drop when the bike warms up.  I have to fiddle with mine while the bike warms up.  When it's warm and I've got it adjusted right, it purrs like a kitten.

Paul

[scratch]

How hard are you braking? Is it possible to slosh the feul in the float bowls to the point the bike will stall?

[The Buddha]

Mine does it too...I have checked evreything...somehitng is wrong but all the user/mechanic adjustable parameters are equal and set near perfect on it...The left cylinder is rich, the right is lean...and that makes the RPM race when warm and stall when you blip the throttle. That's all I can think of...I have the left carb set to 2 turns on mix screw and right set to 5...any more an I am worried it will fall off...I am trying Rashad Carbs next to see if this issue is there.
Cool.
Srinath.

[The Buddha]

BTW mine was much worse...turned out I had a choke cable that had kinked the outer and was pulling the choke open...see if it misbehaves more or less with the handle bars to one side or other.
Cool.
Srinath.

[Toenis]

Hei hei hei, mine was doin` that too - until I switched that damn petcock to "RES". Starvin` @ stop no more - maybe just my luck.
Thats may be releated with vacuum or somth... just make sure you aint` runnin` it on "PRI".

[crmeyer]

[Blueknyt]

i had this same problem when i first started riding my GS, i finnaly got pissed with it, and tore the carbs down, replaced every damn O-ring in them, but i think it was the o-ring Under the slide Guide that was leakin. once all that was done, the problem went away, then it started getting funny again when wheel was turned, found that problem was choke cable. i removed the choke cable as it doesnt need the choke, hit the starter, blip throtle few times and let idle for 2 mins, its ready to go.  havent had any weird stalling problems since.

[scratch]

Thinking out loud...

Petcock to left carburetor vacuum tube? No, if that's loose or leaking, it would be lean. If it's pinched, it would die if not run rich, unless bypassed (petcock set to Prime). Slide diaphragm pinched? Maybe wouldn't allow it to rev that high (restricted movement)? Slide diphragm with hole in it would run rich. Choke effects both carburetors, right? Check to make sure the linkage is connected to both carbs. If one opens and sticks...Or, if gas is leaking past the seat of the choke plunger. How about the carb synchronizing vacuum spigots? Are they capped?

[ac_nvmax]

Hi guys, thanks for all your tips. I'm not a big mechanic and you have me a little confused with some points. Let's see if I can give some more info.

When cold if I turn bike handles to left the bike revs quite high, indicating that a lead from the choke or throttle is sticking. I've been meaning to look at this since I ever got the bike. It can't be that as this problem has occured in last couple months. Also, this problem goes away completely when the bike is warm (strange).

I believe the problem is worse when braking extremely hard but it still occurs when not. The problem goes away slightly when the engine is hot but not much.

The idler on the bike is set to 1600rpms when engine normal operating temperature (and i've reved the bike once to get rid of the formentioned problem).

As i've just got the bike carbs synced I expect not to have a problem with rich or lead mixture, though the only setting I know to turn on the carbs is the idle one. Where are the others?

The point here is, by reving once I clear the problem so whatever one rev is doing is the solution. Thinking logically, when braking somehow the carbs (one or both) must be flooding with petrol. I also noticed that if the bike doesn't stall the revs will pick up to normal by themselves.

When we rev the bike we suck through the excessive petrol, burn it, and then the bike runs as normal.

To backup my thought if the choke is left on high the bike will always rev at 6000rpms regardless of braking or stopping (it's burning the excessive petrol off).

So my one big question is, what would be the cause of this excessive petrol be?

[ac_nvmax]

To answer my question myself, it may be simply be the air filter. I'm using the crappo paper filter unit that came with the original bike and I havn't cleaned it for half a year.

What air filters are u guys with the same problem running and when did you last clean it?

Andy.

[danci1973]

Well, my bike does that (dies on braking/stopping) only if I the choke is on just a little - not if I have a lot of choke and not if the choke is off.

  D.

[Pkaaso]

Not sure if this has been mentioned.  

Is your throttle cable binding up?  You say it's when you turn the bars to the left.  I had the same problem and it was the cable being too tight.

Just a thought.

Paul

[sprint_9]

Be sure to check you petcock vacuum tube going to the left carb as mentioned above.  I about ran my bike into the river cause I couldnt figure out what was wrong, turned out that stupid little hose was off.

[JasonB]

Vacuum leaks can sometimes manifest the problem you are having.

[Blueknyt]

When cold if I turn bike handles to left the bike revs quite high, indicating that a lead from the choke or throttle is sticking.

First off, Pull the choke cable out, remove it from the bike completly while your at it adjust the throttle cable to have a fair amount of slack before it moves the throttle plates, you cant watch the cable every little movement of the bars, start it, let it warm up and go for ride and see what happens.



if this doesnt COMPLETELY solve the issue (though it should improve greatly) it is then time to target the carbs, as stated in prev post, i found my problems were between the choke cable and bad O-rings, my bike hasnt had those symptoms in better then a Year now.

[ac_nvmax]

Thanks for all your replies, I'll report back on Sunday after I've had a good go over with the haynes manual.

[ac_nvmax]

[ac_nvmax]

2 scratch, what are the "carb synchronizing vacuum spigots? Are they capped?"?

Andy.

[ac_nvmax]

crmeyer you have EXACTLY the same problem as me. Have you managed to solve it?