Topic: Another 550 carb question....

[DonMer]

The more I read on here about the carbs, the less I know. Someone mentioned the air cut mod when rebuilding them. What is that? My bike is a 74, are the 77-78 carbs "better"? Can someone point me to a good rebuild post on here? I haven't found a good cover it all post yet.

TIA

[MiGhost]

The air cutout was used on some of the 79-86 PD & VB series carbs. It was designed as an emissions control system to help eliminate afterburn/popping in the exhaust. The modification was to block off this system by plugging the vacuum source to the diaphragm to prevent it from operating.

If you are still running the type 1 carbs on your 74. You should not have these in your carbs.

[lucky]

The more I read on here about the carbs, the less I know. Someone mentioned the air cut mod when rebuilding them. What is that? My bike is a 74, are the 77-78 carbs "better"? Can someone point me to a good rebuild post on here? I haven't found a good cover it all post yet.

TIA

I do not feel that the 77-78 carbs are better. they have the accelerator pump system.
It has more parts and is more complex. The 78's also have the push in jets and slide needles that are not adjustable.
Basically the EPA did everything possible to keep you from working on them.
The accelerator pump system would pollute more not less.

[TwoTired]

The 77-78 CB550 K PD carbs do NOT have an accelerator pump. (You'd think a person with a hundred years working in a Honda shop would know this.)

There are only minor functional differences between the PDs and earlier carbs on the cb550, even though there is little direct part interchangeability between them.  They mostly work the same way.  Use what you got.  They can both be made to work with a modicum of intelligent thought.

None of the Cb550 carbs have an air cutoff circuit.

Use the information in the Cb500/550 Honda shop manual supplements, for repairing the PD carbs.

[lucky]

The 77-78 CB550 K PD carbs do NOT have an accelerator pump. (You'd think a person with a hundred years working in a Honda shop would know this.)

There are only minor functional differences between the PDs and earlier carbs on the cb550, even though there is little direct part interchangeability between them.  They mostly work the same way.  Use what you got.  They can both be made to work with a modicum of intelligent thought.

None of the Cb550 carbs have an air cutoff circuit.

Use the information in the Cb500/550 Honda shop manual supplements, for repairing the PD carbs.

It was not clear what carbs he was talking about.
I was just covering all the bases.
But thanks for that info.

[Bankerdanny]

There isn't a good rebuild thread because these carbs don't need them. The CV style carbs on my GoldWing are complicated and pain in the ass to clean up.

The carbs on the CB500/550 (both styles) are simple and straight forward. It's part of what makes these bikes great choices for a first timer.

It is very unlikely that the carbs will need to be 'rebuilt'. So long as the jet towers in the float bowls haven't been turned into swiss cheese by modern gas, all that is generally required is new o-rings and gaskets, and maybe float needles.

If the airbox and exhaust are stock you should be able to retain the existing jets and slide needles since they really don't wear out.

Order basic carbs kits without jets and needles. Take the carbs off your bike taking lots of pictures in the process to document the location of cables. Then disassemble and clean. Start with a nice clean workbench and do one carb at a time. You should be able to remove, clean and reassemble in a weekend.