Author Topic: 550f running rich?  (Read 2968 times)

Offline DomP

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550f running rich?
« on: October 09, 2025, 07:48:02 PM »
I've not been on here much recently as been busy with work and family, strangely now the best weather is past us I feel I need to get my 550 out again.  I've mentioned before that ive been suffering with what I believe is rich running and I have a question but first the set up-

Standard 069a carbs fully cleaned with the correct jets/needles and in the correct clip position.

Airbox is standard but I have used a Honda 500 air filter as I am missing all the breather hose parts, as a result ive blanked the breather hose port off. 

Fuel is new, tank has been flushed and new tap and filter.  The cam chain tensioner has been adjusted as has valves and timing.

Now if I really am running rich could it be because of the slight airlifted modification?   I can't get smooth acceleration but instead a big flat spot until I hit 4k at which point is snatches horribly, this is the same when in neutral, I can't slowly raise the revs as it sticks at 2-2500 then races away past 4k.

Long shot but is there anyone near Herefordshire that is up for a tinkering session with coffee or beers?  🤞
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline Johnwebley

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Re: 550f running rich?
« Reply #1 on: October 09, 2025, 08:12:24 PM »
Interesting issue,

Have you had the head off?

I live in Hereford,

I could help, have you got vacuum gauges?

Are you available during the week?

Send me a PM in a couple of weeks, as I am in Italy

John

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lifelong motorcycle rider,and fan

Offline DomP

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Re: 550f running rich?
« Reply #2 on: October 09, 2025, 08:17:13 PM »
Hi John, I've fully rebuilt the engine with a rebore by Bryan, are you thinking being a tooth out?  I did it by the book so I'd like to think not but never rule things out,  I'm not free in the week sadly.  Italy, nice!  We were in Brac, Croatia a few weeks ago which has some Italian influences.   I've seen you are in Herefordshire, ironic with the surname Webley😃

I've got a Morgan carbtune
« Last Edit: October 09, 2025, 08:19:34 PM by DomP »
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline DomP

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Re: 550f running rich?
« Reply #3 on: October 09, 2025, 08:37:42 PM »
Oh and much appreciated John!
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline Johnwebley

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Re: 550f running rich?
« Reply #4 on: October 09, 2025, 08:40:49 PM »
Hi John, I've fully rebuilt the engine with a rebore by Bryan, are you thinking being a tooth out?  I did it by the book so I'd like to think not but never rule things out,  I'm not free in the week sadly.  Italy, nice!  We were in Brac, Croatia a few weeks ago which has some Italian influences.   I've seen you are in Herefordshire, ironic with the surname Webley

I've got a Morgan carbtune
Give me a message sometime after the 23rd,

I can bring a 4 gauge carb tuner,

I also have a strobe,

Do you have a remote fuel tank?

We can have a play

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Offline DomP

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Re: 550f running rich?
« Reply #5 on: October 09, 2025, 09:19:31 PM »
That's brilliant John! I've got all of the above too.
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline taysidedragon

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Re: 550f running rich?
« Reply #6 on: October 10, 2025, 12:07:23 AM »
Ignition advancer sticking?
Gareth

1977 CB400F
1965 T100SS

Offline DomP

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Re: 550f running rich?
« Reply #7 on: October 10, 2025, 11:46:12 PM »
The springs have been trimmed byba preious owner, if anything one is too taught.  The advancer itself has benn taken apart and greased so should be no free movement problems.
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline taysidedragon

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Re: 550f running rich?
« Reply #8 on: October 11, 2025, 12:15:50 AM »
The springs have been trimmed byba preious owner, if anything one is too taught.  The advancer itself has benn taken apart and greased so should be no free movement problems.

If you can't find any other cause of the problem it would be worth trying the advance unit with standard springs.
Gareth

1977 CB400F
1965 T100SS

Offline mickwinf

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Re: 550f running rich?
« Reply #9 on: October 11, 2025, 08:56:48 AM »
Where are your mixture screws se? I had similar symptoms on my 500 and the screws have ended up at 2 full turns out.now runs well, May be the modern fuel.
Love the 500 and 550 have a 500 called Lazarus under restoration

Offline K2-K6

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Re: 550f running rich?
« Reply #10 on: October 11, 2025, 10:15:17 AM »
John may have this covered, but his recent experience of running with cam one tooth out needs working through to eliminate from enquiries.

Offline DomP

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Re: 550f running rich?
« Reply #11 on: October 11, 2025, 10:30:01 AM »
I have tried to find unmolested springs but haven't got any as yet.  Ive tried air screws out as for as 2 ½ but it gets unrideable 
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Online McCabe-Thiele (Ted)

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Re: 550f running rich?
« Reply #12 on: October 11, 2025, 11:40:02 AM »
There is a simple test to check if the valve timing is a tooth out.
No cam cover removal just something to do with what the valves are doing at tdc?
IIRC Bryan or Ken posted it ages ago.

I've forgotten what you do, it might be in my 500 rebuild blog.
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 neat street

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Re: 550f running rich?
« Reply #13 on: October 11, 2025, 12:37:29 PM »
Quote
Airbox is standard but I have used a Honda 500 air filter as I am missing all the breather hose parts, as a result ive blanked the breather hose port off.


dont think the breather port should be blocked off... any thoughts?? this may cause some issues???

CB500 1975
CB750F 1976
KLX250 1983
Lambretta SX200 1979
Mini Mayfair 1984

Offline Bryanj

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Re: 550f running rich?
« Reply #14 on: October 11, 2025, 01:09:48 PM »
The port on the airbox can be blanked off but not the hose from top of enginge