Pre 600 dies after several minutes of running

[nedfunnell]

Hello,
I bought an 88 GSX600F last fall and have been fixing it up- one of the issues the seller described was that it would run for just a few minutes, then die. You could ride for a few blocks, maybe a mile, then it would die. I cleaned out the carbs and expected this to fix it, but I've found that I have the exact same problem. Does anyone know what this problem could be?

[Wild-Bill]

How do the plugs look? Fouled?

Is the choke shutting all the way off (on all 4 carbs) when you turn the lever back to the top? It may be something as simple as a sticky choke cable or bent choke slide.

[nedfunnell]

How do the plugs look? Fouled?

Is the choke shutting all the way off (on all 4 carbs) when you turn the lever back to the top? It may be something as simple as a sticky choke cable or bent choke slide.

I just replaced the plugs. I pulled one out for what I think is an unrelated issue (left it on prime, one cyl filled with gas- sticky float in a carb, right?) The one I pulled out looks blacker than I expected for just having been in for tuning and test riding, but maybe that's normal.

My choke works differently- I have the 88 carbs, which are BST31something whereas 89-later Pre bikes have BST33something carbs. My choke is just a knob on a spring-loaded bar that slides out. I haven't looked specifically at how the choke is working, but it seems to do its job- it starts kind of hard when cold and I can control the engine speed roughly by how much choke I'm giving it.

[Wild-Bill]

OK, so no cable to worry about. Black plugs are a sign of running too rich which fits your description of the symptoms.

Make sure all 4 choke plungers are closing fully. It's possible that the slider bar has a bent fork or two keeping one or more cylinders running on choke when you thought you had the choke off. It's also possible that the A/F screws are set too rich, the pilot jets have been swapped for fatter ones or that the needles aren't seating all the way into the mains. Lots of possibilities but the choke (enrichment) circuit is probably the most likely.

[arsenic]

No, 1990-1997 are BST33SS, 88-89 are BST31SS. You are correct, 1988 carbs had the choke on the carbs, 1989 was a cable actuated choke.

[nedfunnell]

OK, so no cable to worry about. Black plugs are a sign of running too rich which fits your description of the symptoms.

Make sure all 4 choke plungers are closing fully. It's possible that the slider bar has a bent fork or two keeping one or more cylinders running on choke when you thought you had the choke off. It's also possible that the A/F screws are set too rich, the pilot jets have been swapped for fatter ones or that the needles aren't seating all the way into the mains. Lots of possibilities but the choke (enrichment) circuit is probably the most likely.

OK. I'm also at high altitude- 6000 feet. Could that be a part of the problem? When I put the carbs back together I took note of the jet sizes which match the ones spec'd in the service manual. Perhaps they need to be changed for the altitude? I'm moving back to sea level in a couple months, though, so if I could just adjust the A/F screw to get by for a while that'd be good. Could you point me to a resource on how to adjust the A/F screw? How can I check the needle seating? Also, can anyone give me tips on how to fix my non-functional float issue?

Also, Arsenic- where can I get a gasket/seal kit for these carbs? I am fairly sure that my bowl gaskets are shrunk to the point of not sealing.

Thanks!

[Wild-Bill]

Ladies and gentleman, let me introduce the Rain Man!

Seriously, now that you've checked in to this thread, got any input concerning what's causing his bike to die?

OK. I'm also at high altitude- 6000 feet. Could that be a part of the problem? When I put the carbs back together I took note of the jet sizes which match the ones spec'd in the service manual. Perhaps they need to be changed for the altitude? I'm moving back to sea level in a couple months, though, so if I could just adjust the A/F screw to get by for a while that'd be good. Could you point me to a resource on how to adjust the A/F screw? How can I check the needle seating? Also, can anyone give me tips on how to fix my non-functional float issue?

Also, Arsenic- where can I get a gasket/seal kit for these carbs? I am fairly sure that my bowl gaskets are shrunk to the point of not sealing.

Thanks!

Sputter, choke, cough...
You might have mentioned that the carbs are AFU. Grab a copy of Carbs 101 and get those carbs right.

Rebuild kit: http://www.carbkitscapital.com/carb_...&model=GSX600F

[nedfunnell]

Ladies and gentleman, let me introduce the Rain Man!

Seriously, now that you've checked in to this thread, got any input concerning what's causing his bike to die?



Sputter, choke, cough...
You might have mentioned that the carbs are AFU. Grab a copy of Carbs 101 and get those carbs right.

Rebuild kit: http://www.carbkitscapital.com/carb_...&model=GSX600F

Shucks, OOS on the carb kit. Got another source?

[arsenic]

I'm really not much help on the 88-89 carbs. I tend to shy away from them. However, I have this set that isn't AFU.
carburetors carbs Suzuki GSX600F Katana 600 88-89

[nedfunnell]

I'm really not much help on the 88-89 carbs. I tend to shy away from them. However, I have this set that isn't AFU.
carburetors carbs Suzuki GSX600F Katana 600 88-89

I couldn't even begin to afford that, sadly- in fact I'm on the brink of selling my bike and want to get it ridable either for sale or to keep.

[Kreylyn]

You said it runs for a little while then dies. Will it start right back up, or after a few mins and run doing the same thing? Or will it not start at all for a long time (after the engine is cool again)?

Fuel in the oil can make it run rich, true... Change the oil, fix the leaky carb. That would make it run terrible warm.

A limited fuel flow would keep the carbs from refilling for the short duration aspect... faulty petcock, kinked fuel lines, partially stopped up inline fuel filter, etc...

Krey

[nedfunnell]

You said it runs for a little while then dies. Will it start right back up, or after a few mins and run doing the same thing? Or will it not start at all for a long time (after the engine is cool again)?

Fuel in the oil can make it run rich, true... Change the oil, fix the leaky carb. That would make it run terrible warm.

A limited fuel flow would keep the carbs from refilling for the short duration aspect... faulty petcock, kinked fuel lines, partially stopped up inline fuel filter, etc...

Krey

It will start back up OK the first time, but no power. Starting will be harder each time it dies until it gets nothing. I smell gas after trying to start, so I think it is getting at least some fuel. I haven't tried starting it any sooner than the next day, but I can give it a shot.

What's the fix for a stuck float? They were all moving freely when I put the carbs back together. Can I check the petcock operation w/o a mityvac?

[kevin2502000]

+1 on gas in the oil.

[Kreylyn]

It will start back up OK the first time, but no power. Starting will be harder each time it dies until it gets nothing. I smell gas after trying to start, so I think it is getting at least some fuel. I haven't tried starting it any sooner than the next day, but I can give it a shot.

What's the fix for a stuck float? They were all moving freely when I put the carbs back together. Can I check the petcock operation w/o a mityvac?

Clean float needle seats of varnish.
Replace damaged/worn needles.
General clean (floaties in the bowls hold open float needles)
Adjust float heights
Replace damaged/fuel filled floats.

You can test simply if the floats are leaking... fill them with fuel through the fuel line. Blow on fuel line... if you can blow through them at all, you got a float needle not sealing off and need to check/fix that.

You can test the petock by simply sucking on the vacuum line to open it. Put a temp fuel line from it into a container so you can see the flow when you apply vacuum. It should not take much to make the fuel flow and flow well. Once you apply vacuum, fold over the vacuum line, and it should hold the vacuum for a good while to keep the fuel flowing.

Krey

[nedfunnell]

OK, took the carbs off the bike today. Question (see pic)- what are those two tubes coming off of the lines between carbs 1-2 and 3-4? When I blow into the fuel line to check the floats, air comes out of them. Should they be hooked up to something? They weren't when I got the bike.

None of my floats are sealing correctly- I think I must have set the float height wrong when I put the carbs back together. I thought I was doing it right, measuring from the bottom of the carb body straight out, but maybe not- any tips there?