CX500 GL500 650 Global

Pardon me for butting in gentlemen,

bri-guy, when you get a moment, please go back to your post 'what are these' in the general problems section. I'd like to work on image problem there if you don't mind. Read my response and we'll go from there, I REALLY want to figure this out before my head pops.

THANKS

OK picture issues aside here is the latest. I cleaned the in-tank filter of god knows what that brown sludge was. Sloshed around aquarium gravel in the tank for a bit and got it and the gas/water out. Got some interesting brown liquid back out BTW. Pulled the carbs and cleaned the fuel bowls and jets (not really dirty that I could see). Re-installed the carbs and poured gas down the carb hose and buttoned it all up and installed an air filter that was missing to my suprise. Got it to fire after a half dozen tries or so. Now it idles a little rough and if I give it gas it immediately stalls. It sat and idled for 10-15 minutes without any hiccups which is reassuring, just a little rough I guess you could say. I hoped it would run better after cleaning it all up, not worse. This is frustrating, but not unexpected on a 25+ year old bike with an unknown maintenance history. Was I correct in connecting the vacuum line from the carbs to the fitting on the petcock that is to the outside (the diaphram cover). The inside one is vent right?

Suggestions, theories?

bri-guy, I'm not sure I'm following you on the petcock hose routing, so just to get this straight, be sure that the hose from the nipple on the right carb goes to the FRONT or forward-most nipple on the petcock, the REAR nipple on the petcock is simply for venting.

OK, so the petcock is right. I have the carb hose going to the most forward nipple and the rearward one is open to vent. Now all I need to do is get it to run properly other than idle. One item down, several more to go.

Wheres our resident carb expert when we need him.

Hello bri,
OK, from what I have read, you have cleaned the tank out and refilled the Mississippi river with mud. It sounds like there is a blockage inside the carbs, or a blockage in the main fuel system.
BTW: have you checked to see if the gas cap vent is plugged. If it is, it will cause a vacuum inside the tank as you use fuel, and not let the fuel flow into the carbs. That could make it seem as if the bike was running out of gas and bog down. Loosen the cap when it starts to run bad and see if that helps.

Also, the diaphragm in the petcock could be faulty or full of gunk. Have you taken it apart to clean out the inside of it from all the mud stuff you found in the tank? The mud does not stop at the filter when it is as fine as that. It could have compromised the vacuum diaphragm, and is not letting enough fuel to flow through it. Just because the vacuum is actuating the system, does not mean it is flowing enough fuel.

I can't emphasize enough how important it is to make sure EVERY part of the fuel system is clean and flowing smoothly. Even the air bleed parts of the system. Without air flow, there is no fuel flow. At least not for long anyway!

You need to have a constant fuel flow to the carbs also. Not just filling the hose with enough to fill it up once. Get a one gallon plastic gas can and hook up a hose to the vent side of it.Find one that has a tip on it that you can attach a hose to. Tip it up so that the main pour spout is now your vent, and run the bike that way.

Hey I've had this same problem minus the vacume petcock. The sledge plugged up the reserve side of the petcock and filled up the inline filter and the really tiny grits of sledge slid by the filter filling the last 3 inches of the hose going into the carbs. Was a pain to clean it all out assuming that I got it all or atleast most of it.

Had to blow air through the reserve side of the petcock to free it. Not sure how yours works but you might want to take it apart.

Would a blockage in either the gas cap vent or petcock diaphram allow it to idle for 10-15 minutes? Or would it seep enough gas to idle, but not enough to power the bike when the throttle is tweaked. I will take it apart once again and see if the sludge got into the petcock itself and pull the cap and see what that does. Since I am taking it apart, I might as well rebuild the petcock just to make sure. I will also replace the in-line filter to make sure it isn't blocked with stray crud. I did spray the carbs and intake tubes with carb cleaner and no change in RPM, so at least there are no apparent leaks. I also replaced all the bowl screws with allen heads. Should make taking them off much easier in the future. When it did stall it started right back up, just can't give anything more than idle.

I poured fuel in the carbs to get some there to allow the bike to start easier. I understand that it will take a lot more gas to run and once running the system should have kept the bowls filled on their own.

Thanks for the help.

It's possible and it's happened to me that after re-fitting some small minute particle has got flushed up into the float needle valve hole/s.As you have fitted the allen screws(Wise move) take the bowls off and blast upwards into the float valve holes with some Brake/Carb cleaner and re-fit bowls and see if that helps?

Bri-guy,
Yes, a blockage in either the gas cap vent or bowl vent(s) would not allow enough fuel flow - I suppose it could idle though. As far as the petcock goes, on my 82 GL, I simply unscrewed the petcock 'bowl' from the petcock while it was still on the tank so I could check the screen (mine was spotless).

I'm going to GL wrote:Bri-guy,
Yes, a blockage in either the gas cap vent or bowl vent(s) would not allow enough fuel flow - I suppose it could idle though. As far as the petcock goes, on my 82 GL, I simply unscrewed the petcock 'bowl' from the petcock while it was still on the tank so I could check the screen (mine was spotless).

Good point about the fuel cap.If the breather hole is blokced or not large enough due to age(I've drilled mine out a little) it can cause a vacuum in the tank thus impeding fuel flow.