Question about 1979 Suzuki Gs 550 L
My bike has good air flow and suction. The gas is going to the carbs and comes out of the gas tank fine and yet the spark plugs are not wet with gas or anything. Back by the air filter doesn't have any scent of gas. Please help.
CK FLOAT AND NEEDLE VALVE IN CARBS SOUNDS LIKE THEY NEED TO BE CLEANED AND ADJUSTED.
Posted on Apr 22, 2014
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Posted on Jan 02, 2017
Hi ..... Go through the above list, pay particular attention to fuel delivery ie blocked breather in tank, any filter fitted to tap or change in line filter if fitted. Easy to check, take off fuel delivery to carb (place container to catch fuel), start bike and fuel should come out a strong contant flow.
Let us know how you get on.
Posted on Jan 20, 2009
SOURCE: Bike won't stay running
Drain the carburetors. There should be a screw on the lower side of each CARB float bowl. Remove the screw then replace it after the fuel drains. Remove the water trap bowl at the bottom of the petcock, (gas valve). Is there any water or trash in the bowl? Drain a cup of gas from the tank. Is there any water or trash in the cup? Dump it, clean it and re-mount it, (not all bikes have a water trap bowl). Install new stock NGK spark plugs.
Remove the CARBS from the bike.
FOR EACH CARB > Remove the float bowl and clean the entire CARB with a spray CARB cleaner from the auto parts store. Wear protective goggles to avoid getting spray in your eyes. Spray into all the little airways and fittings in the CARB. Remove the idle screw and the air screw on the outside throat of the CARB and spray into the screw holes as well.
< < READ CLOSELY > >
Be sure to put these two screws back in the same hole they came out of. IMPORTANT > do not tighten these two screws down. Only screw these in until they LIGHTLY seat. Now turn each screw one and one half turns outward. Put the rest of the CARB back together, clean the air filter and install the CARB. Install an in-line fuel filter. Let the float bowl fill then start the engine.
BALANCE THE CARBS
Turn the throttle screw on the LEFT CARB one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left CARB to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.
Now turn the throttle screw on the RIGHT CARB one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right CARB to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.
SYNCHRONIZE THE CARBS
Remove the air filter and rubber fittings to allow you to see into the throat of both CARBS. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each CARB such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other CARB.
With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other CARB so that the slide on that CARB just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both CARBS begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.
Turn the idle screw on each CARB EXACTLY ONE HALF turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed. Congratulations, you have just balanced and synchronized your CARBS This should fix the problem. One last and VERY IMPORTANT thing, Have a fire extinguisher handy and ready for use any time you work on or with he CARBS.
Please rate this solution. Thanks throttlejock!
Posted on Apr 22, 2009
Lean mixtures burn very slowly, at times slowly enough to continue
burning through the power and exhaust stroke, causing a backfire when
the intake valve opens, and that flame gets a shot at the new mixture
In normal operation, as the engine slows, the fuel delivery from the main circuit falls off, and the idle circuit is supposed to take over. If the idle circuit flows insufficiently, that becomes a transition to fuel starvation.
You can try pointing an unlit propane torch into the inlet air, and see if you can get closer to an idle while supplying a supplementary fuel source. You will need to do this in a way that gets propane to both carburetor inlets, maybe rigging a Y with vacuum hoses and electrical tape...
This started with work on the carburetors, so the fuel system would be the most suspect. That, and the fact that it will run at higher RPM would seem to rule out fuel delivery.
I was looking around at photos while developing this answer (needed to know whether this was a twin or a 4-cylinder), and one resource said the idle speed should be 1,200. I don't know if that's right, but maybe 1,000 RPM is too slow for this motor to keep it together. (I do doubt that, though.)
When I wrote that last sentence, I started to second guess myself, thinking "What if the fuel shutoff(s) is/are vacuum operated, and as the bike approaches idle there is insufficient vacuum to hold it/them open?" But the I rejected that, because there is even less vacuum at cranking speeds, yet the bike starts.
Posted on Jun 26, 2010
The float is stuck open in the leaking carb. Remove the float bowl and clean the carb after removing the pin holding the float in place. While the float is out, shake it to see if gas has gotten inside it. If so, you will need a new float or will need to drain the float then re-solder it to seal it up again. To drain the float chances are you will need to drill a vent hole in it to allow the gas to drain. Just solder the vent closed when done.
Posted on Jul 14, 2010
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