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Hello to the GS forum. This is my first post. I'm seeking expert guidance to fault source and correct what appears to be a chronic overfuelling problem with my 1982 GS550L (BS32SS carburetors). I have been riding and working on motorcycles for 45 years but have never encountered such a frustrating problem and have reached my limit.
Background - Acquired as a non-runner with 8000 miles in excellent condition a few years ago. Bike was receved with one plug cap removed from its lead and cracked. No running history was available as the original owner had passed away. I chased electrical gremlins for three years which turned out to be internally failing coils. I did manage briefly to get the bike running well with the original coils and had it up to 100mph one day before the coils overheated and failed again, so I know the bike will run strong. After installing dyna coils this year (huge improvement in the size of spark BTW), new leads, new caps and spark plugs, I ran the bike again and had fuel spitting into the air box. All four plugs become severely carbon fouled after less than 5 or 6 miles of riding.
Carburetor work performed - I dismantled the carburetor bodies (still ganged together), had them dipped, flushed every orifice out with carb cleaner and compressed air, then proceeded to rebuild them.
At a tremendous cost, all new OEM Suzuki parts were used, including:
Float needle and seat assemblies,
Main and Pilot jets,
Fuel mixture screws and O-rings,
Vacuum diaphragms and O-rings,
Float Bowl gaskets,
Pilot jet plugs,
Vacuum piston return springs.
Original Air jets were cleaned and re-used. Choke pistons were left in place during the dip procedure but the choke was propped open and cycled periodically in the dipping process to ensure all old fuel deposits had been removed. They appear to function withiut binding. Number one was removed to inspect the tip and it appears to be intact along with the viton seat at the head of the choke piston. Needle and seat assemblies were gently lubed with a trace of grease to protect the O rings upon installation.
Float height was measured with a micrimeter in accordance with the excellent pictorial by Ed Ness and set initially to 22.4mm. All four were within .06mm of this value.
Fuel screw settings were not listed in the Clymer or Haynes manuals but I set them to 2 1/2 turns out.
The vacuum pistons move freely. Carbs were bench synched and subtly adjusted to restore proper idle.
The bike fires up effortlessly but the first ride had the plugs foul up uniformly, as described. I reset the float heights to 23.4mm to address the spit-back into the airbox (successful) but with litlle improvement in the plug situation. The Idle also tended to hang more as the bike heated up with the lower fuel level. The bike pulled clean and strong when cool, but ran rougher as it heated up, pointing to a rich mixture problem.
So there it is. Floats are now set to their limit. What could I possibly have missed?
Background - Acquired as a non-runner with 8000 miles in excellent condition a few years ago. Bike was receved with one plug cap removed from its lead and cracked. No running history was available as the original owner had passed away. I chased electrical gremlins for three years which turned out to be internally failing coils. I did manage briefly to get the bike running well with the original coils and had it up to 100mph one day before the coils overheated and failed again, so I know the bike will run strong. After installing dyna coils this year (huge improvement in the size of spark BTW), new leads, new caps and spark plugs, I ran the bike again and had fuel spitting into the air box. All four plugs become severely carbon fouled after less than 5 or 6 miles of riding.
Carburetor work performed - I dismantled the carburetor bodies (still ganged together), had them dipped, flushed every orifice out with carb cleaner and compressed air, then proceeded to rebuild them.
At a tremendous cost, all new OEM Suzuki parts were used, including:
Float needle and seat assemblies,
Main and Pilot jets,
Fuel mixture screws and O-rings,
Vacuum diaphragms and O-rings,
Float Bowl gaskets,
Pilot jet plugs,
Vacuum piston return springs.
Original Air jets were cleaned and re-used. Choke pistons were left in place during the dip procedure but the choke was propped open and cycled periodically in the dipping process to ensure all old fuel deposits had been removed. They appear to function withiut binding. Number one was removed to inspect the tip and it appears to be intact along with the viton seat at the head of the choke piston. Needle and seat assemblies were gently lubed with a trace of grease to protect the O rings upon installation.
Float height was measured with a micrimeter in accordance with the excellent pictorial by Ed Ness and set initially to 22.4mm. All four were within .06mm of this value.
Fuel screw settings were not listed in the Clymer or Haynes manuals but I set them to 2 1/2 turns out.
The vacuum pistons move freely. Carbs were bench synched and subtly adjusted to restore proper idle.
The bike fires up effortlessly but the first ride had the plugs foul up uniformly, as described. I reset the float heights to 23.4mm to address the spit-back into the airbox (successful) but with litlle improvement in the plug situation. The Idle also tended to hang more as the bike heated up with the lower fuel level. The bike pulled clean and strong when cool, but ran rougher as it heated up, pointing to a rich mixture problem.
So there it is. Floats are now set to their limit. What could I possibly have missed?
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