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I need a carb sync - Anyone in North London?

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michtag:
Hi guys,
I've been chasing gremlins (and possibly ghosts) on my 1977 CB550K3 ever since I got it 20 months ago. Done very little riding (almost none), lots of tinkering, got burnt by a mechanic that did some things right and some other he messed up completely, I cleaned the carbs several times, changed spark plugs and caps, air filter, manifold o-rings, new condensers.....basically everything I could think of that could cause my problems.

Aaaanyway, with 30 years of Vespa riding, I am a novice when it comes to Hondas. I have a great passion for mechanics and I believe I have done all I should have done so far (mostly a 3k tune-up) to a decent level, BUT, I have nobody to be able to check that for me, so I may be chasing my tail forever.
The bike starts fine, just a little choke, and idles ok, but as soon as it warms up (2 mins or less) the idle fluctuates, with no input from me, between 1000 and up to 3000 rpms. This is a great improvement to what it was as it used to shoot up to 5k and would hang in between gear shifts, which made it unridable.

The battery is fully charged....but then again, I am not riding this often at all and have recharged several times, so it may well be the battery itself giving me problems, but I need to eliminate other things before I think about replacing that.

The last 2 things I "believe" I need at this point are
-Timing set with strobe light (I have done the static, but assuming the advance mech. springs may be a bit weak only the strobe lamp will shed true light on this (sorry, this is a terrible "dad" joke....my kids would be ashamed)
- Carb sync: I have the necessary gauge tool and I have watched several videos on how to, however I have never done before and I don't have a proper space to do it (without annoying a few neighbours...)

My question to the audience:
Anyone in North London area (I am in N5) who could help me with these last 2 tasks? I have an old strobe light and the gauges set for the sync, but never really used them before and I would appreciate an expert and watchful eye from a more experienced member.
I tend not to trust my bike too much (it's probably all in my mind) and I am weary of getting stuck on the side of the road, but there are worst things in life and I will of course travel 10-20 miles to reach you.
I will also wear a facemask and keep social distancing, needless to say.

Anyone available around here?
Alternatively, anyone knows a good mechanic around here who would do it (and knows how to) without skinning me alive?

Cheers
Michele

[Edit]
Went for a short ride today (4 miles, city roads) and I have a feeling the bike is not as sharp as it should be, it feels it can't get all the power out (and I am just opening the throttle in 1st, 2nd or 3rd) a bit like when you have something stuck in your throat and your voice's not clear.
So, re-checking points gaps and timing (will try using my strobe light) will be my priority this week.
Any other suggestions are welcome, as I said, I have no real term of reference in my experience....

K2-K6:
If you've not anything sorted in a while I'll go over it with you,  but on holiday for a couple of weeks unless we get covidded?  out of our family camping trip to Cornwall  :D

Can work with your kit to familiarize and build your knowledge.

Back about 29th August,  let us know after if you still want help.

michtag:
Thank you so much K2-K6!!!!
I'll see what I manage to do (or re-do) in the next couple of weeks and then get back to you on this. It would be great to have an expert check what I am doing :)
Cheers
Michele

K2-K6:
"[Edit]
Went for a short ride today (4 miles, city roads) and I have a feeling the bike is not as sharp as it should be, it feels it can't get all the power out (and I am just opening the throttle in 1st, 2nd or 3rd) a bit like when you have something stuck in your throat and your voice's not clear.
So, re-checking points gaps and timing (will try using my strobe light) will be my priority this week.
Any other suggestions are welcome, as I said, I have no real term of reference in my experience...."

To help in the interim,  it's sounds possible from your above observations that you may have a  cylinder not firing.  The points each run two cylinders so if either is a problem you get both from that supply stopping and it's even hard to pull away,  so doubt if it's that.

More likely it could be just one.  If you start it from cold and run for about 20 seconds,  switch off and then feel each of the exhaust pipes youll tell if you've a cold one ( that will feel more like the "something stuck in your throat" you describe) if that's the case then ordinarily you're looking at a fault of the HT part of the system from coil through plug cap to plug itself as initial suspect.

Anyway,  post how you get on and shout if you wish to have help.

paulbaker1954:
Are you positive you don’t have an air leak between carbs and head. That would also cause similar problems. Try spraying carb cleaner around the joints when running. I had exactly the same tickover issues with revs suddenly rising and fixed it with new inlet rubbers. I also used jubilee clips (thin stainless ones) as opposed to the old Honda clips as even the replacement ones I got (not  aftermarket ) from DSS were no sealing well.

From the sound of it this is more likely the problem

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