CB550 F 1976

[Matt1976]

Hi all, new to the forum and having been enjoying my CB550 F for a couple of years right up to this summer when I started having problems.

It lacks power under weight like it’s missing and won’t tick over. What had replaced so far:

New battery, coil pack spark plugs, converted to electronic ignition (old crank was bent) getting 13amps back to the battery over 2000 revs. Checked and adjusted the valves. Carbs cleaned new jets and set up.

I’m at loss now as what could be wrong, has suggested replacing the alternator?

Thanks

[Oddjob]

Replacing the jets is usually a mistake unless you source genuine Keihin jets. Keyster jets are known to not be as good.
Sure you mean 13volts not amps. If so that’s low, around 14 volts is more like it at 4k.

[Matt1976]

Sorry volts! I had the Carbs refurb with an after market needle, jet kit and seals!

[Sesman]

For clarity, the power problems occurred after the carb re-fresh? If so I’d try cleaning and reverting to the original brass. Was there a reason why you replaced the brassware?

[Matt1976]

I had carbs cleaned and all seals replaced as they were all brittle and leaking petrol, I was assured at the time it was all balanced and it did run for about 20 miles with no problems but know since all the stuff that I mentioned has been replaced it’s running like a bag of nails! Will go back to the carbs!

[Bryanj]

What make of electronic ignition and honda or other coils?

[Sesman]

I’d start with the carburettor brassware then move onto the ignition system.

I presume the top end of the motor was un disturbed during the work? I’m thinking valve timing. I ask as you stated the “crank was bent”. Did you really mean the ‘crankshaft’, necessitating a full engine rebuild?

Folk have used the non OE carb kits with variable success, but generally they have a reputation for being poor, especially needles and slow jets.

Replace the alternator! If you are charging satisfactorily I doubt you need a new alternator!

[McCabe-Thiele (Ted)]

Hi all, new to the forum and having been enjoying my CB550 F for a couple of years right up to this summer when I started having problems.

"converted to electronic ignition (old crank was bent)"

Thanks

Have you changed the actual crankshaft when you say crank was bent?
Have you done the work yourself ?

I would be checking the Alternator connections as well as the rectifier & regulator connections,

[taysidedragon]

Before you start pulling everything apart start with the simple things. Check that the fuel is getting through to the carbs, fuel filter not blocked, fuel cap breather hole not blocked. Are the spark plugs genuine, there are a lot of cheap rubbish copies on the market.

Also check air filter is clean, air intake not blocked.

[Oddjob]

Most people think the crank is bent when the bolt holding the advance/retard mechanism to the end of the crank is bent. This causes the mechanism to wobble as it rotates, causing major running issues, normally happens when the bikes dropped hard on its right hand side, usually takes out the chrome points cover at the same time. Sometimes the mechanism is ok afterwards, sometimes not.

Whereabouts in the UK are you?

[Matt1976]

Thanks all for the suggestions somethings to further dig into.

Yes it was crank (probably not the correct terminology) and not the crankshaft that was within the ignition points that was out of shape hence the advice was to put electronic ignition (invested in a good quality one). The valve clearances have all been checked as well.

Based in North Wales UK

[Athame57]

Welcome here Matt.
You'll find lots of expert advice to draw on! 

[Bryanj]

Again what make of electronic, some can be bad out of the box, even the good named ones

[scottly]

What do the spark plugs look like? Are they black and sooty, clean and dry, clean and wet etc.

[McCabe-Thiele (Ted)]

Ah you mean the distributor cam or  lobe.