small vacuum leak !

[GScanada]

Hey guys , new to the forum and proud owner of an 89' Gs500, its my first bike ! bought it as a small project and came across a few little things that have me going !



so I realized that the bike wouldn't start but it would turn over but not fully , made sure that its getting fuel . checked to see if it was getting any air . changed the air filter .. still the same problem . so a friend of mine realized that the vacuum line that goes into the left side of the carb is cut ... changed it . still nothing . then she decided to spray some brake clean into the vacuum port and BOOM turned over fully ! so I said ill check out the petcock .. cleaned it out put it all back together and nothing ... very lost at this point .. I also noticed that on the bottom right sided of the carb there is the same port .. not sure if they should be hooked up .

any help is much appreciated ! thank you!

[Falken Hawke]

Start by turning the fuel selector to PRI and attempt to start.  The selector valve is opened with engine vacuum in "ON" but if it has failed, will not flow fuel.  In "PRI", fuel flows from the tank to the carburetors with no control.  While the bike can operate like this, on a get-off, fuel can pour freely from the tank through the carbs creating a fire hazard.

If the engine starts in PRI but not in RES, replace the selector valve.

If engine does not start, open the carburetor bowl drains to ensure fuel is in the bowls.  If they are empty, unbolt fuel tank from its mount under the seat.

Turn petcock valve under tank off and disconnect fuel lines from the valve.  Keeping petcock valve over a bucket, open the valve to verify fuel flow.  Replace petcock if necessary.

If the petcock is good, remove lines from selector valve and ensure they are clear of debris, reconnect or replace the lines, turn the valve back on, and disconnect the fuel line from the selector valve to carburetor.  With the selector valve in PRI, fuel should flow from the outlet.

If fuel still does not flow, replace the selector valve.

If the carburetor bowls have fuel in them, start by cleaning and inspection.  Rebuild if thorough cleaning doesn't help.

[GScanada]

thank you for replying , I followed what you have said to a T. petcock works ... when we had the vacuume line connected to the carb and just for the hell of it sprayed break clean again it turned over . . so so odd . so I took of the hole carb and took off the rubber mounts and used a wire Brush to clean off the metal surface. ran out of break clean . so were thinking a smoke machine would help .

ps used a diagram to make sure all lines are connected the right way . getting real frustrated ... it gets spark and gas . drained the carbs .. also put new gas in .. and nothing .

[Falken Hawke]

Spraying carb cleaner into the vacuum line is the same as spraying starter fluid down the carburetor.  The engine will try to start but if fuel isn't going through the carbiretor properly, it won't continue running.

As long as it is certain fuel is going through the selector valve, the carburetors will have to be torn down.

[Armandorf]

Check gas is getting into the carb bowls. Check float level with u Tube .Also, you can taper the vaccumm hose from carburetors for now.

[Kilted1]

Sounds to me like your carbs are in need of some attention.  You've verified that fuel is flowing from the tank to the petcock, presumably it's getting to the carbs, and the engine is basically working.  So that leaves carbs.  There's no sense cleaning them and putting all the old bits back in, the O-rings may be leaking, so get yourself a pair of rebuild kits and do a thorough job of it.  It's really no more work to do it right the first time and replace everything during the cleaning process.   

[GScanada]

thank you guys for your help . I came to that thought today . I did a rebuild kit on them already . looks like something isn't right on them . time to take them apart again and see whats up

[herennow]

There is a mistake in some of the hose routing drawings, check the wiki for the corrected version.
this has been mentioned, but I just want to clarify, on prime unscrew the little drain plug on the bottom of your carbs and make sure fuel is flowing it should be around about a cup a minute. Obviously capture the fuel in a container

Try not to spray brake cleaner into a carb, you could damage the rubber components.