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Stattz is it running yet

3311 Views 22 Replies 5 Participants Last post by  LiLBull
Stattz waiting for an updtae on your new machine ...
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don't know about the 1978 carbs but the 1974 carbs have a way of adjusting the slide on the needle in addition to a way of synching the carbs up. Sounds like you are trying to adjust the carb synch instead of the slide on the needle. the gurus at might know a little better so ask over there. The slide should not be totally closed or the bike will not run, they should probably be 1/8th of an inch open (just guessing here).
to stazz's credit the bike came with the carbs in a box and completely disassembled. He's just trying to undo what the previous owner did. eerybody is saying that stock is the baseline and I agree, if you can put the carbs back to the factory settings and start from there you should be able to get a good solid starting point. after that if it leaks fuel adjust the float height, if it runs high, adjust the idle screw and air bleed.

the things that need to be set to stock:
needle height (adjusted in the slide.
float height
air bleed (fuel) screws
Idle screw (on the linkage)

and the slide height adjustments need to be close to the same.

When the bike swings from one extreme to the other, there is usually more than one problem going on. For instance when you first had it running @ 4000 rpm it may not have been the carbs at all but air leaks in the manifold (did you check the rubber intakes for cracks? are they hard or soft?). This is the point in the bike where you really need to check everything carefully. if you can get it running again I usually spray the motor with soapy water (not in the carbs but definatly on top of the manifold) while running and check for air leaks. if the soap bubbles up you have an air leak.

BTW, I hope you changed the oil and filters befor your last startup. starting a single cam with year old oil in it isn't healthy. Most of the single cams I find in storage actually have no oil in them. Your cb550 has an internal oil tank (it's shared tranny motor oil) so make sure you have enough.
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can you post a pic of your carb rack so we can see what is going on.

the air bleed screw (fuel screw) should be on the side of each carb body near the opening. On older carbs it used to adjust the amount of air bleeding in the idle circuit (hence the name air bleed screw) but newer carbs (1969+) it actually adjusts the fuel flow at idle. There are some honda carbs where they didn't have individual fuel screws but a nob beterrn #2 and #3 carb at the bottom of the rack.
IIRC there are 4 or 5 different carb types for the cb550 from 1974 to 1978. One is for the 1974, then 1975-1976 and then 2 or three different ones for 1977-1978. The 1974 and 1975-76 are similar with subtle differences, but are way different than the 77-78 different carb types.

The manual covers only two different carb types the 1975-76 and one of the 1977-78 carbs. It is possible that they carb the books covers is different than what he has on the bike, however really all that changes between the different 77-78 models is the location of certain adjustment screws and linkages.

This is why I recommended posting this at since there will be guys there intimatley familar with these specific carbs.

I know of the carbs you have stattz but the only time I had a bike with them I shitcanned them and replaced them with the 75-76 carbs which make more power and are way easier to work on.
I posted it for you and here is the response so far:

quote: Yeah he has a mess there. As you said those carbs arent covered in the Clymers. Maybe he can get ahold of an actual Honda shop manual for the 78. The screws he messed with under the top cover are for syncing the carbs. He seems to be under the impression that there are two screws for air/fuel mixture. As you know there is one screw per carb and in his case they meter fuel. They are the screws under the carbs, in front and center of the float bowls(toward the engine) and they are mounted vertically. If he bottoms them out clockwise then turns them out 1.5 to 2 turns, that should be a good base point. He'll need to pull the carbs again and try to bench sync them(sorry I dont know the specs for the slides) then sync them while its running. He should be able to measure the clearance on the cut away side of the #2 carb and match the others to it. The #2 carb is the "preset" carb and is the one that you match the others to durring a sync. Match carb 1 to 2, then 4 to the others and finally 3. He'll probably end up having to increase the vacuum on 1 and 4 a bit once he does a running sync since their inlets are longer. I think the screws he mentions having the yellow torque paint on them are for adjusting choke but Im not certain. All said, he should probably find a set of carbs that havnt been pulled off the bank or messed with, and use those as a reference. Nothing wrong with having extra carbs and parts right?
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