CX500 GL500 650 Global

I did pull the petcock bowl and cleaned the screen, although it was pretty clean. I will give it another look.

Another thought - IMO, upon complete disassembly, you should be able to tell if there is a need for a petcock rebuild - would hate to see you spend on rebuild kit you don't need. I'm leaning towards carb contamination issues too (yuk).

I will pull the petcock and disassemble the whole thing this time, just to make sure. One thing I did notice when I was draining the tank is that I had to apply pressure to the line to get the petcock to open for gas flow. I thought it was vacuum that opened the diaphram? Did I connect to the wrong fitting, or is this a tell-tale sign?

I'm glad I only put back a gallon or so of gas and not the full tank I had at the start.

Shep, so I understand you correctly. Pull the bowls and shoot carb cleaner into the float needle valves and holes with the floats still on the carbs? When I had the carbs out I did take the floats out (one at a time) and cleaned the needle valves. In general the carbs insides were clean. No obvious sludge or varnish I could see. Even the jets looked nice and clean. I am gonna just squirt everything I see there with cleaner and hope it dislodges whatever might be there.

Could it be that the carbs are so horribly out of sync that is why it shuts off when given an throttle? I did turn the mixture screws on the bottom of each carb and got no response with a turn or two in each direction. I did put them back to the original position though.

Looks like I am gonna get all gassy again this week. Good thing the wife is patient and not complaining about the $1300 paper weight in the garage.

When do get to ride and not sit and idle I wonder? Its ok though JC Whitney just told me my tires are back ordered till the 3rd anyway. So lots of time to get the bugs
out till then. All I know is these tires better be the greatest thing since sliced bread.

If I get this thing running I am gonna owe you guys a beer.

Getting the carbs right on these bikes can take a few goes because of their age and lack of maintenance.Out of my two CXs the one I built from spares never seems to give me trouble with it's carbs yet the other one always does even with different carbs I have.Go figure as they say.

What colour are the plugs?Is it possible you have weak coils that are breaking down when hot?

I don't know about the plugs color, but would idling 10-15 minutes be long enough to heat up the coils? I will give the plugs a look and let you know. Will clean and re-gap while they are out once I get a plug tool. My sockets at home are to thick to fit down the cylinder holes.

I did pull the coils and cleaned all the electrical connections. Everything seemed pretty good. It ran fine before this, just started breaking up after driving around for a half hour or so. Couldn't get it over 3-4k RPM. The coils were my first thought till I saw the crud on the petcock tank filter.

It still sounds like some crud may have got through to the carbs but of course if the carbs were well out of sync you can get a rev block which I've had before.I know my engines so well now that if I get any hesitation at any rev band I can feel it.One of mine a couple of years slipped out-of-sync even though the locking nut hadn't moved.Once I'd re-balanced them they were good to go again.
You must get a spark plug spanner/wrench for the bike otherwise you cannot diagnose some of these things.Plugs can tell sooooo.... much about what is going on with an engine.
You need a 12mm long reach or like I use a Special 19mm socket that has a 12mm inner with rubber grip for sparkplugs that goes on an extension bar on my Wrench.

OK, Bri, lets go back to basics. First of all, did you clean and tighten all the electrical connections in the whole system? Corrosion can cause a lot of different problems. If you have a dirty or loose connection, the heat build up in a short time can cause part of the ignition system to start to fail due to resistance in the wiring. Refer to the post I did on electrical connections.

YES, a set of carbs that are out of sync can keep the motor from responding properly because the 2 carbs are fighting each other. They have to be as close as possible for them to like each other and work together.

You are trying to fix this with little band aids here and there. Take the plunge and pull the carbs fully apart and do the full cleaning if the balancing does not work. Make sure all the parts are clear and the sliders are free also. There is no substitute on these bikes for doing any thing less than checking every single detail. It takes me a week or more to do a set of carbs properly. But when I'm done, I know I won't have to question them again, and if I have another problem somewhere else, I can focus on that and not the carbs. They are the heart of a smooth running bike. Crud can hide in a lot of different places and cause problems.

Shep is right, you need to get the tools to take the plugs out and see what they look like. It is the window to the fuel systems diagnosis.

I don't remember how long your bike sat before you got it, but either way, everything has to be checked and cleaned from all the electrical connections to every part of the fuel system, oil system, mechanical adjustments and so on. The previous owner might have done thing so badly, that it might be the reason the bike was abandoned and left to decay.
Blowing out the jets might only push any thing in there around and not get it out. You need to commit to it and rip it down.
You might spend less time doing it right than chasing it piece by piece. You have a couple weeks before you get the tires right. Spend the time wisely. A clean fuel system is priceless in this situation.
Go for it.

Good ideas LRCXed, you reminded me of something...

Bri-guy, something simple to check : On my 82 GL500 I forgot to tighten the upper rear air box mounting bracket where it bolts on under the seat (right side). This bolt is also a critical ground location and if left loose, it will cause mysterious rough running/stalling etc and may cause component failure. Sorry I didn't think of this sooner

I have been cleaning any terminals and grounds that I see, as I go around the bike. I didn't know about the one behind the air box, but will give it a look tonight and make sure it is connected and is clean. I will go through the fuel system again and see if I can get it running a little better. If that does it then I know it was fuel and will take the carbs apart, I don't have gauges to balance the thing so will have to make the hardware store one for now till I get the proper instruments. Either way I would have to order the carb kit and that could take a few days to arrive. Once I have the plugs out I will let you know what I find. My goal right now is to get it running decent and then move up from there.

Who do you recommend for a carb kit?
Will keep you posted.

Give goergefix's a try. Call or Email him at his site. You can find the link in the USA reference post here in this site. http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=17&t=39

When you make your balancing tube set, make sure you put a very tiny restriction in the ends of the tubes so the vacuum signal smooths out and keeps the fluid moving slowly.