hmm the sound is I guess the sound of it bogging, after 4k. If you left the throttle say 3/4 open around 4k I would think it would eventually stall. In neutral it revs up usually very nice, sounds pretty impressive, no bog, but not when you are riding it.
There is no o-ring just the rubber connection, which looks good, but I will check with wd-40. It also dawned on me that when I pulled out the main jets, I didn't unscrew the jet from the tube because they were pretty much one and I didn't want to damage them, and they looked decent after I cleaned them up. I guess this might be worth looking at again as well.
Thanks again,
ugmold
Definition:
v. bogged, bog·ging, bogs
v.tr.
To cause to sink in or as if in a bog: We worried that the heavy rain across the prairie would soon bog our car. Don't bog me down in this mass of detail.
v.intr.
To be hindered and slowed.
[end def.]
Is this what you mean?
The engine will slow down when the mixture is not correct for combustion. Either too lean or too rich may cause the engine to not pick up as requested.
If the engine burbles/stumbles when the throttle is opened and then sputters back to life, this is usually a sign of too rich.
If the engine abruptly drops power, and won't pick up until the throttle is once again reduced, it is probably too lean.
The 78 550K has lean burn carbs. In order to appease the EPA, the carbs were set for as lean an idle mixture as they could get away with.
When the throttle slides are suddenly opened, the vacuum depth in the carb throat reduces. It is the vacuum that draws fuel through the carburetor jets. Therefore, whacking open the throttle makes the mixture lean and the engine reduces power.
The 750 actually added an accelerator pump to the carbs during this era, that actually shoot raw gas into the carb throats when the the throttle is opened.
The 550 didn't get this accelerator pump for some reason. Apparently they could leave the idle mix just over-rich enough to allow the throttle to open a "reasonable" amount and still get pickup within expectations.
The earlier 550 carbs were all set very rich at idle, and thus, have more tolerable behavior to throttle opening aggressiveness.
As you might guess, the Idle Mixture Screws (IMS) can have a large impact on sudden throttle opening engine response. Setting them too lean will exacerbate, the "Throttle Whack Wheeze".
These IMS adjustments also have a much more limited effective range than prior model carbs (also to placate the EPA and limit user tempering with emission limits. Also why the the idle jets are not field replaceable). So, there is only so much you can do with the screws to improve "Throttle Whack Wheeze".
The air filter restriction has a direct influence on the vacuum level in the carb throat (remember vacuum is what pulls the fuel through the metering jets?) removing the air filter or changing the type (such as pods) again makes the idle mixture lean, and induces more severe "Throttle Whack Wheeze".
Other considerations, bits of info:
The 550 uses rubber couplers to attach the carbs to the intake manifold. And, there are orings that seal the join between intake manifold and cylinder head. These can both leak, particularly if disturbed after a 30 year residence.
So, assuming the carbs are clean, the exhaust still has the same back pressure as when delivered by Honda, the air filter has the same restriction as was delivered by Honda, the IMS screws are not turned in too far, the throttle response from idle setting should induce reliable engine pickup when open by up to one half total throttle travel. If it does not, then something in that previous sentence needs to be addressed.
Midrange throttle response has similar factors, accept that the mixture is dominated by the slide needles. (The slow system in the carb is still providing some fuel, though). So, assuming the carbs are clean, the exhaust still has the same back pressure as when delivered by Honda, the air filter has the same restriction as was delivered by Honda, the IMS screws are not turned in too far, AND the slide needles are in the proper adjustment position, the throttle response from midrange setting should induce reliable engine pickup when open by up to one half total throttle travel. If it does not, then something in that previous sentence needs to be addressed.
The main jet dominates the fuel mixture at throttle setting of 3/4 to WOT. There shouldn't be much "Throttle Whack Wheeze" there. But, if the engine isn't making expected power at those settings, then the main jet size needs to be addressed.
Finally, all the fuel metering systems in the carbs have an effect on operation in throttle positions other than where they dominate. So, changing fuel delivery in any one of these may induce a required change in another. If your bike is stock and still has all the stock components, then reassemble it to the way it was delivered adjusted by Honda, and it will run pretty darned well.
Cheers,
