Author Topic: 550f running rich?  (Read 2972 times)

Online McCabe-Thiele (Ted)

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Re: 550f running rich?
« Reply #30 on: October 13, 2025, 07:24:35 AM »
A socket spanner with a pass through bar not a ratchet or one sided tool.

www.ebay.co.uk/itm/187506333851
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline DomP

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Re: 550f running rich?
« Reply #31 on: October 13, 2025, 07:32:01 AM »
Ah ok, to turn the crank
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Online McCabe-Thiele (Ted)

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Re: 550f running rich?
« Reply #32 on: October 13, 2025, 07:34:09 AM »
Ah ok, to turn the crank

I found that a T bar enabled one to rock the crank very slighty left or right with plugs removed.
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline deltarider

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Re: 550f running rich?
« Reply #33 on: October 13, 2025, 08:11:15 AM »
I always use a T-handle and a 23 mm socket when cranking some millimeters a CB500 for timing. I estimate the risk of damage by removing the spark plugs far higher than cranking that WASHER, SPECIAL which, btw, is still the original... Things may be different with a CB750. I've seen more than once that problems that can occurr on CB750s, were bluntly transferred by experts to CB500550s.

Online McCabe-Thiele (Ted)

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Re: 550f running rich?
« Reply #34 on: October 13, 2025, 08:24:25 AM »
I always use a T-handle and a 23 mm socket when cranking some millimeters a CB500 for timing. I estimate the risk of damage by removing the spark plugs far higher than cranking that WASHER, SPECIAL which, btw, is still the original... Things may be different with a CB750. I've seen more than once that problems that can occurr on CB750s, were bluntly transferred by experts to CB500550s.

Luckily in my case as it was an engine rebuild the plugs were still out from the head decoke.

I share your fears every time I take a plug out of an alloy head.
« Last Edit: October 13, 2025, 08:26:31 AM by McCabe-Thiele (Ted) »
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline DomP

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Re: 550f running rich?
« Reply #35 on: October 13, 2025, 04:56:50 PM »
I agree with plugs out, I hate the idea of plug chops to tune a bike
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline K2-K6

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Re: 550f running rich?
« Reply #36 on: October 13, 2025, 07:00:42 PM »
I always use a T-handle and a 23 mm socket when cranking some millimeters a CB500 for timing. I estimate the risk of damage by removing the spark plugs far higher than cranking that WASHER, SPECIAL which, btw, is still the original... Things may be different with a CB750. I've seen more than once that problems that can occurr on CB750s, were bluntly transferred by experts to CB500550s.

Luckily in my case as it was an engine rebuild the plugs were still out from the head decoke.

I share your fears every time I take a plug out of an alloy head.

Take them out hot to avoid many problems ... makes a significant difference.

Recently in technical/advisor and oversight capacity  :) (son bought his first car) a significantly complex all aluminium V8 with plugs right down the end of long tubes, they seemed too tight and felt risky to me when he tried to remove them to inspect, bringing it up to temp through running and they came undone easily.

Although against advice from many manufacturers, I use a smear of copper grease on thread when installing.

Offline DomP

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Re: 550f running rich?
« Reply #37 on: October 13, 2025, 08:59:03 PM »
I got mt Trafic glow plugs out this weekend in the same way, I'm also a copper grease fan on threads but reduce tightening torque slightly as ive read it can cause inaccurate torque settings due so the slippy surfaces
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline exvalvesetdabbler

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Re: 550f running rich?
« Reply #38 on: October 13, 2025, 10:51:35 PM »
A bit of a long shot but here goes..

On my 400 F I had rich running, tail pipe smelled a bit too much like the choke wasn't coming off.
After a lot of poking around and swapping carb internals it turned out that the emulsion tubes had  worn a bit oval internally where the throttle slide needles go. 

The other symptom was stumbling of and on the throttle at low revs and the adjustment of the pilot air screw made little sense. Plugs were a dark colour bordering on being sootey.

Put some new needles and emulsion tubes in and the problem disappeared.

Regards
Dave

The difference between old and new was visible if the needles were inserted into the emulsion tubes and rocked side to  side.


« Last Edit: October 13, 2025, 10:53:22 PM by exvalvesetdabbler »

Offline deltarider

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Re: 550f running rich?
« Reply #39 on: October 14, 2025, 08:17:11 AM »
[...]
After a lot of poking around and swapping carb internals it turned out that the emulsion tubes had  worn a bit oval internally where the throttle slide needles go. 
[...]

Put some new needles and emulsion tubes in and the problem disappeared.
[...]
This is in contrast to what I experienced the other day. For a silly reason - to be explained later - I had the carbs on the table. I closely examined needle jets and needles. On reassembly I accidently have mixed up jets and needles - so they were not the pairs they were before, and to my surprise bike runs nicely. The same accidental mix up happened to float needles and their valves and again: no negative effects. These parts have been in service over 140.000km. Makes me wonder what parts have been in your carbs: aftermarket or OEM and the same question to which parts you have put in now. 

Offline exvalvesetdabbler

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Re: 550f running rich?
« Reply #40 on: October 14, 2025, 09:18:44 AM »
I used  genuine parts, this was done around 2010.  No reason to doubt the origins of the originals since I have had the bike since 1980 with only 18k on the clock at the time.

Regards
Dave.

Offline DomP

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Re: 550f running rich?
« Reply #41 on: October 14, 2025, 10:18:19 AM »
With this in mind might it be worth trying my needle clip one lower, which on an F will be the last position.?  All of my parts are genuine Keihin and correct for carbs/bike
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline florence

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Re: 550f running rich?
« Reply #42 on: October 14, 2025, 11:59:46 AM »
Sorry if you have tried these things already.

I'm assuming you have had the carbs set up and balanced.

Are the chokes opening fully?
Is it flooding, are the float heights correct?

Offline DomP

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Re: 550f running rich?
« Reply #43 on: October 14, 2025, 01:18:06 PM »
Yeah I've ve had the carbs off, set float heights, bench synced,  balanced etc.  I must be missing something though
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline taysidedragon

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Re: 550f running rich?
« Reply #44 on: October 15, 2025, 11:37:50 AM »
With this in mind might it be worth trying my needle clip one lower, which on an F will be the last position.?  All of my parts are genuine Keihin and correct for carbs/bike

If you put the clip one groove lower that will raise the needle and make it run richer.

Try going the other way, put the clip one groove higher to lower the needle.
Gareth

1977 CB400F
1965 T100SS