Trouble with bike

[beardylondon]

Hi All

My 550 has sat for many months due to life getting in the way.

We fitted a new coils middle of last year, it ran ok, but was a bit lumpy and spluttered.  Put it away for winter and now it wont start.
It is at my Dad's, and I haven't got time to look at for a few weeks. He is only familiar with old British bikes, he has tried all the normal things, but can't get it to start. Battery is good, fuel is good. He thinks perhaps points.

Any tips and tricky greatly appreciated.

[Johnwebley]

I am not sure, but the modern petrol isn't much good in storage,

What carbs does it have?

Some can be trouble some if not used regularly

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[Bryanj]

Need more details on what it is like year, model (K of F) etc

[beardylondon]

As per my sig, 1976 CB550 K2 (USA import)

Not sure on carbs tbh, I’ll find out and report back

[McCabe-Thiele (Ted)]

Did you add any fuel stabiliser?
With the battery fully charged it might be worth a shot of easy start into the air box. If it fires up that might indicate petrol issues/oblocked jets.

[beardylondon]

Yes fresh fuel and fuel stabiliser added in October/Novemeber.

Good shout on easy start !

[Sesman]

Kill switch…🫣

[martin_uk]

I have experienced many issues in past with E10 petrol due to 10% ethanol content.

One of main problems is the drawing in of water from atmospere and damage to rubber parts not designed to resist

I go out of my way to use Esso E5 Super as was the lowest ethanol %

[beardylondon]

I only use Super unleaded, I believe Esso have changed their mix in the last 18 months, apparently it was less than (advertised) 5% ethanol. Not so sure now.

[K2-K6]

In addition to other suggestions in trying for response, cover air intake with a rag/towel and crank it in restricted intake "mode" with alternate throttle wide open or closed.

This can encourage  them to draw through jets that are a little reluctant to get going.

[deltarider]

[...]
It is at my Dad's, [...] He is only familiar with old British bikes, he has tried all the normal things, but can't get it to start. Battery is good, fuel is good. He thinks perhaps points.

So your dad thinks it's ignition related. Let's start there. What was the reason you replaced the coils?
First question is, are the plugcaps connected well? Are plugcaps themselves still OK?
Then to the points. Are points surfaces clean? Do NOT clean them with paper or carton like business cards. I've learned from personal experience that some residu of it can prevent points from contacting.
When you manage to have it run 'lumpy and spluttered', this video may help you diagnose a faulty condenser: https://www.youtube.com/watch?v=t3cuvGVwnjI At the breakerpoints a bit of sparking is normal, excessive sparking or arcing is not good and can indicate a bad condenser. In this vid the left condensor (1+4) is bad, right condensor (2+3) is good.
Video: courtesy Ulf Penner
If you can't get the engine to run, Youtube has tutorials on how to test a condenser aka capacitor. You don't need a Fluke, any cheap DMM will do.  https://www.youtube.com/watch?v=gg2emZ91mxI from 01:30 on. I'm suggesting this because you fitted new coils. When people suspect the coils, in many cases the condenser(s) is/are the real culprit.

[andy120t]

 If it was running before, then unless anything has changed I would assume it'll start again..but maybe something is blocked.
My Zephyr 550 was running poorly after sitting for a while so I used Valvoline Carburettor Cleaner which, once the engine is hot  ( and I used easy-start to get it running because it wasn't starting) is sprayed into the air intakes, the leave the engine running for a bit...and it cleans out the gummed up stuff. On mine I could hear the moment when the carbs suddenly cleared up and it began to run properly. Saved me taking off the carbs and cleaning them out.

[beardylondon]

It started up, wasn’t kill switch.

It will tick over and when revved it pops and sputters badly, on idle, without touching the throttle it will randomly increase revs.

The mystery continues…

I will check out above, re: condenser, thank you!

Carb cleaner a good shout too!

[Johnwebley]

I occasional tip a good measuring of Redex carb cleaner in the tank,

That will get inside the system

Hopefully clear it out

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[K2-K6]

It's very often some level of restriction within the idle jets and their circuits.

Carb cleaning products worthwhile trying as a simple non invasive way to assess if it'll improve.

The slow/idle modulation does so much on these carburettor, making it look like serious fault is present when in reality it's these.