78 GL1000 carburetor question

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Tom_Charlton

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Jun 9, 2012
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Location
Centralia Illinois
My Bike Models
1984 GL1200I
1988 GL1500
Carb(s) started spilling gas on the engine. Pulled the rack and found gas in plenum. Reset the floats so float valves would shutoff quicker. While in there, checked the jets. Nothing plugged and the slides moved without sticking. Venting stopped, but carbs seem to be running rich.

Put it back on the road and it was sluggish until 5000 rpm, then cleared up and pulled hard and quick to redline in all gears (straight road, no traffic, new tires). Once the rpms got below 5000, became sluggish again. Spark plugs were sooty; so I cleaned them, but it made no difference.

Time for complete carburetor teardown and rebuild?
 
1000 has a bunch of air jets too. Probably doesn't need a total rebuild but it will need the carbs cleaned well it seems.Jets cleaned and passages flushed.
 
If gas is spilling out there is an o'ring or seal leaking, there is no overflow tube on these they just flood the cylinders. It sure sounds rich still.
The thing to do is pull the carbs and fill them on the bench and see where they are leaking,need a 3 foot length of hose to mimic the fuel pump pressure(3lbs).
Floats should be set to specs and not leak , you might just need new float needles, old ones were not Viton rubber and most older and originals have swelled or deteriorated and wont seal, as well the tiny float needle springs are fragile/weak and tend to stick when old. It sounds like at least one or more o'rings or plenum seal are leaking.
 
If the carbs have never been done properly you can spend a lot of time racking your brain trying to sort out what a proper rebuild will do. Order Randakks kit, and his video and you will be amazed at how well the stocks perform. Mine are seamless from 1.5k to 8k with excelent throttle response. The only way to know that everything in there is correct is to tear into it yourself and make it right.
 
To solve you have to pull the carbs..take the caps off, hookup a fuel source at least 6' above the cabs..to simulate 2-3 lbs. of pressure..now look into the carbs..is gas coming up through a jet = float needle issue or float setting issue, if not there then a o ring issue between carb and plenum..paper in the plenum will help Id the source.

PS the carbs must be level on your bench use a small level across the plenum top to check, adjust with Popsicle sticks under the intakes as needed.
 
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