Topic: hesitation off idle

[KeithB]

If it is too rich during the hesitation, the engine will burble as it gains RPM.  If too lean it won't advance at all.

This is as accurate a description as I can give and by the look of the plugs, it's too rich at low RPM.
The idle jets are correct and clean and I blew air through the idle cct and it all seems fine as well.
Back at it today and going to remove the stock air intake so I can get those carbs on and off easier and see if the cause might be air intake restriction. (long shot..I know)
I will not make any changes to the carb adjustment and see what happens.
If there is no change in the 'hesitation" or "burble", I will try the suggestion to re-clip the needles to a leaner setting.
I want to sort this today and move on!
Will post results later.

[KeithB]

Carbs installed with no changes and stock air box removed...slight reduction of rich idle.
Still hesitates but not so bad.
Here is a pic of clean plug left to idle for 2 minutes. Looks about right to me.

Removed carbs and re-clipped needle to second groove from top.
hesitation pretty much gone and idle jet screws now make a difference.
However, as to be expected, I have a lean condition at 3/4 to WOT.

Don't have the patience right now to try to get that %$#@ air box back on.
I'm hoping that the stock air intake and filter might bring the 3/4 throttle lean condition back to where it needs to be.

Am considering re-clipping needles to 3 rd groove before installing stock air box.

[flybox1]

As a rule of thumb, because they all.overlap, tune the main jet( 3/4 to wot) first, then needle clip position(mid throttle range), pilot jet, and lastly the idle circuit and air screw.

[KeithB]

Progress!!
The hesitation has not completely gone but it has been reduced and is much more manageable.
Engine pulls smoothly through to WOT with no leaning out.
I drilled the 2 sets of lower holes in the emulsion tubes to .036 (64)and installed the stock air box.
Needles are clipped at second groove from the top and stock 100 mains.
All good except now I have a leaking float bowl gasket
I have worked on a number of bikes but never have I come across an air intake set up as badly designed as this!
When you look at a '74 550 and a '74 750, it looks like the air intake and carbs were designed on different planets!
 It's hard to imagine they came from the same manufacturer.
Even my V4 Hondas were not as much trouble!

Thanks to all for you time and input

[flybox1]

I drilled the 2 sets of lower holes in the emulsion tubes to .036 (64)and installed the stock air box.

[TwoTired]

Glad you are happier with your bike.

I have worked on a number of bikes but never have I come across an air intake set up as badly designed as this!
When you look at a '74 550 and a '74 750, it looks like the air intake and carbs were designed on different planets!
 It's hard to imagine they came from the same manufacturer.

The Cb550 is not difficult if you use the proper sequence/technique.  It's a compact design that works well.  And, it was not expected to have untrained people work on them.  And even then, not very often.  40 years later and they still work on many.  Not my definition of a bad design.

Anyone have a flat rate manual for carb replacement on this bike?  I expect it is less than 45 mins. R/R.

However, if the carb couplers need replacement, are hard, and non-compliant, it does become more challenging.

Even my V4 Hondas were not as much trouble!

Then, you are certainly not using the correct sequence for the CB550.
The V4's are far more more horrid.  And the GL1100 carbs would put you in therapy, I expect.

[iron_worker]

Maybe he has the wrong air box for his bike ... which might describe why he can't install it and why he has tuning issues.

LOL


IW

[KeithB]

I drilled the 2 sets of lower holes in the emulsion tubes to .036 (64)and installed the stock air box.

Maybe he has the wrong air box for his bike ... which might describe why he can't install it and why he has tuning issues.

LOL


IW

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Had a chat with Hondaman and he suggested this mod to improve fuel atomisation at partial throttle setting.
Seems to have helped.
I'm not about to argue with his experience.