Wing tips #2

[mikenixon]

Pilot screw adjustment
The four-cylinder Wing's carburetors were made smaller almost continuously throughout its production. In 1975 the carb's venturi was as big as it would ever be. Three years later in 1978 it would shrink, and in 1980 it shrank again when the GL1100 emerged. Finally, the carbs shrank still more on the 1984 GL1200. The reason? Honda apparently changed their idea of what kind of bike the Wing was supposed to be, after initially positioning it as a quasi-sportbike (yes!, check out the period Honda ads) and quickly repurposing it in response to America, Honda's biggest market, redefined the Wing as a luxo-tourer. The fact is, due to their being substantially oversized, the GL1000's carburetors, absent an accelerator pump (whose purpose is to overcome lazy intake air speed), very badly need one. For this reason, most knowledgeable techs are liberal with the GL1000's idle mixture screws, adjusting them richer than factory spec to at least partly compensate for the GL1000's lack of good airspeed at idle, and as a result this adjustment mimicks an accelerator pump's benefit. The over-rich setting effectively provides the only available fuel compensation when the bike's biggish throttles are yanked open from idle, and as long as it isn't overdone, presents no drawback in terms of idle performance.

On-the-bike cleaning procedure
Sometimes simple things work well. Got a call yesterday from one of my customers. His Texas-based house and garage were swamped by the recent storms and he asked advice on getting his roughly-idling GL1000, already cleaned out of water and mud, including the tank and float bowls, running perfectly again. I suggested he remove each of the carb's four idle air bleed hoses and spray some brake cleaner aerosol into the idle air bleed jets (within the brass elbows) and after repeated liberal sprays using the red aerosol can's hose, to dump each carb's resulting spuge out the carb drain screw. Using the air bleed openings allowed access to the idle jet and idle circuit from outside the carburetor, with the opportunity of an at least 50/50 chance of making a difference, seeing as how the idle jet is the smallest passgae in the carburetor and thus the easuest to clog and mostly likely the problem. He called me last night to tell me it worked. The bike idkes sweetly and responds to throttle well once again.

[Whiskerfish]

Absolutely Agree. People get hung up on the book settings. Personally I do the idle drop then add a full turn or more based on the bikes throttle response. I like the idle drop as it also verifies that carbs idle circuitry is operating 100%.

[ericheath]

Has anyone ever noted which side of the idle jet gets plugged? Bowl side? Or throat side?

That’s a good one to add to the on-the-road potential cures. I wonder if putting a finger over the three holes and primary jet in the throat wouldn’t increase the chances of back flushing it into the bowl. Or alternating pressure through the pilot screw opening ?

[mikenixon]

Has anyone ever noted which side of the idle jet gets plugged? Bowl side? Or throat side?

That’s a good one to add to the on-the-road potential cures. I wonder if putting a finger over the three holes and primary jet in the throat wouldn’t increase the chances of back flushing it into the bowl. Or alternating pressure through the pilot screw opening ?

It's a good thought. I think though that there is enough resistance in the idle circuit to build pressure. Plus the aerosol, especially if the hose end is carefully tapered on sandpaper, pressurizes pretty good.

As for the jet, at just 0.013" it plugs very easily. Bowl side for sure, as that is where all the dead dinosaur juice resides.

[mikenixon]

I like the idle drop as it also verifies that carbs idle circuitry is operating 100%.

Steve, I remember that you do, and you I'm sure remember I don't. But now you have given me a reason, and it is an interesting one. Glad of that. Widens my thinking a bit.

[mikenixon]

Pilot screw adjustment
The four-cylinder Wing's carburetors were made smaller almost continuously throughout its production. In 1975 the carb's venturi was as big as it would ever be. Three years later in 1978 it would shrink, and in 1980 it shrank again when the GL1100 emerged. Finally, the carbs shrank still more on the 1984 GL1200. The reason? Honda apparently changed their idea of what kind of bike the Wing was supposed to be, after initially positioning it as a quasi-sportbike (yes!, check out the period Honda ads) and quickly repurposing it in response to America, Honda's biggest market, redefined the Wing as a luxo-tourer. The fact is, due to their being substantially oversized, the GL1000's carburetors, absent an accelerator pump (whose purpose is to overcome lazy intake air speed), very badly need one. For this reason, most knowledgeable techs are liberal with the GL1000's idle mixture screws, adjusting them richer than factory spec to at least partly compensate for the GL1000's lack of good airspeed at idle, and as a result this adjustment mimicks an accelerator pump's benefit. The over-rich setting effectively provides the only available fuel compensation when the bike's biggish throttles are yanked open from idle, and as long as it isn't overdone, presents no drawback in terms of idle performance.

On-the-bike cleaning procedure
Sometimes simple things work well. Got a call yesterday from one of my customers. His Texas-based house and garage were swamped by the recent storms and he asked advice on getting his roughly-idling GL1000, already cleaned out of water and mud, including the tank and float bowls, running perfectly again. I suggested he remove each of the carb's four idle air bleed hoses and spray some brake cleaner aerosol into the idle air bleed jets (within the brass elbows) and after repeated liberal sprays using the red aerosol can's hose, to dump each carb's resulting spuge out the carb drain screw. Using the air bleed openings allowed access to the idle jet and idle circuit from outside the carburetor, with the opportunity of an at least 50/50 chance of making a difference, seeing as how the idle jet is the smallest passgae in the carburetor and thus the easuest to clog and mostly likely the problem. He called me last night to tell me it worked. The bike idkes sweetly and responds to throttle well once again.

Pardon the misspellings. Typing one-handed with my iPad in the other hand... Always several bad outcomes of this...

[5speed]

I asked this before..I think. lol
As an old school 4 barrel carb guy..has anyone tried setting the idle mixture via a vacuum gauge?
I haven't set it on my 76 yet and have to check the timing first but I might attempt this method for my own curiosity..