Judge my CB550F2 1977 idling

[alexdecker]

Hey all

This is my CB550F2 from 1977 idling. Does this sound okay to you?

https://www.youtube.com/shorts/xxPyy_B_-Uw

- Alex

[Johnwebley]

Sounds ok,

Possible one cylinder out of sync

Have you checked tappets

Used a carb vacuum gauge system to do the balance

But it seems smooth and reliable



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[McCabe-Thiele (Ted)]

As you have asked the question I suspect the engine clatter is louder than it was at idle?

I'm no expert btw, It sounds to me as though there is a miss match at lower revs between the pairs of cylinders.
I would be checking the timings for 1/4 & 2/3 if you still  have points, plus the valve clearances, then carb balance.

There are members here whose views will be backed up by decades of experience that should help.

[Skoti]

As John has already suggested the carbs are most probably out of synch.

Once corrected you will have smooth and nice idle.


I use Morgan Carbtune.

https://www.carbtune.com/

[K2-K6]

As already noted, needs some adjustment to better optimise running.

I agree with Ted's impression, that it sounds like a pair of twin cylinders slightly out of harmony, and his advice to make sure the ignition is accurately set for both points.

Notice it sounds a little a horse cantering with that four beat rising and falling.

Carburettor synchronisation a suspect, but if ignition is out there's no point in trying to synchronize the carburettors first.

Verify the ignition setup is accurate, then look at carbs.

[Oddjob]

Where in the UK are you Alex? Maybe someone local to you has some vac gauges if you haven’t.

[deltarider]

1. Always check ignition first. I recommend to have 1+4 and 2+3 breakerpoints at the same dwell or, if you use feeler gauges, the same gap as close as possible. Then check the timing. When needed, repeat procedure.
2. Sounds to me a synch will bring improvement.
3. I recommend an idle at 1200 rpm.

[Oddjob]

Nobody seems to have asked the question, what have you done to it? Has it gone that way slowly as the mileage grew higher? Have you recently done some work on the engine and that’s the result. If so what work. My first impression was it wasn’t fully chiming on all 4 cylinders. When you rev it slowly you can hear a slight hesitation around 2000 revs, when you rev it hard it’s harder to spot that. Seems to be better at higher revs than lower. Could be a slightly blocked idle circuit or just bad timing, points or electronic? No one has asked. Points wear, electronics don’t tend to, set them up correctly and they should be fine. When you approach the bike I can hear a noise like an exhaust gasket blowing, has it been off recently? Are all the nuts still tight?

It doesn’t sound that bad tbh, phones always tend to make them sound more clattery than they are in real life. It doesn’t sound that bad a little flat so I suspect carbs more than anything else.

The idle speed is 1000rpm, if it ticks over fine at that speed the engine is normally fine. Just turning the idle speed up is like turning up your car radio because the big ends are knocking, it cures nothing, just disguises the problem and ends up costing you more in the end.

Try and see what the engine sounds like when you rev it really slowly, it highlights the problems more. I suspect it will sound worse around 2000 than at tickover, sort of hesitant and uneven.

[exvalvesetdabbler]

Sounds like a bit of clutch basket rattle. Take the dip stick out and have a listen.

Regards
Dave

[Oddjob]

For some reason the 550 seems to be worse than the 500 for that. They both use the same shim system but tbh most people don’t even know that’s there. However the damper rubbers which hide inside the clutch basket seem to deteriorate faster in the 550 than the 500. I’ve taken 4 550 baskets apart and 3 were knackered, of the 3 500 baskets I took apart the only1 was knackered. Not sure why that is other than the drive gear being different between the 2.

They are replaceable but it’s very difficult to find a source of the rubbers.

[alexdecker]

Thanks all for the replies!

I just switched all the boots on both sides of the carb and this was the first time I ran it. I noticed small swings in the idle, but wanted to know how this was as a baseline. I will probably do a complete maintenance with cam chain, valve adjustment, timing and vacuum sync. Just figured I might not need it if it was only the boots I had changed.

An idle that goes up and down, is that also a vacuum sync, or is that something more severe like an air leak?

I actually hadn't thought about any strange knocking noises. The primary chain is new, but whenever it idles and I don't have the clutch lever pulled, it always rattle a little more. Just figured that was the nature of the beast. But with your comments here, I might have to look into the clutch plates or springs or anything else?

- Alex

[exvalvesetdabbler]

The clutch rattle is usually a combination of worn rubber dampers in the clutch, a bit of slop on the  primary chain and amplified by any imbalance in the carb sync or other effect that means each cylinder is not producing the same bang as the one next to it.  From idle, rear brake on, in gear, Then let the clutch bite a little, normally quietens  down at that point.

[Bryanj]

Vac sync is the LAST thing to do after tappets, points gap, timing and cam chain.
UNLESS the carbs have been played with doing a full service normall puts the carbs within tolerance, i think Ken will confirm that!

[Oddjob]

Alex did you change the orings in the manifold brackets? A good old mucking around getting the carbs back in and out could disturb the vac settings, doesn’t take much. As Bryan says if nothing is disturbed it should go back to it’s last settings but I’d check them just in case. Also as Bryan says, last thing you do after all the other maintenance items.

As for the clutch, there is inbuilt end float on it. You’re supposed to pull the basket along the shaft and see how much it moves before the circlip stops it. You then shim the excess away. If that’s not been done the basket moves back and too along the shaft and can create noise. It goes away when the clutch lever is pulled as that loads up the basket. However, as time goes by another factor comes into play that never really reared its head in the past, the basket damper rubbers. They are like the rubbers surrounding the rear wheel cush drive, the sprocket carrier. Except Honda never meant for the clutch ones to be changed. They go hard and brittle and start to crack. That allows the large gear bonded to the basket at the back to move, when that does it creates all sorts of noise and the clutch take off from stationary gets jerky or snatchy as the gear is just rattling back and too. The only cure for that is a new basket or to replace the rubbers with new ones. Doing that is difficult and tbh beyond most members on here. Much better to just replace but it’s finding a basket that hasn’t got bad rubbers. If you remove the clutch case you can do a quick check on the state of the rubbers by just locking up the gear wheel with a screwdriver between it and the primary gear. Now grab the basket and try and move it, both in and out and from front to back. In and out, shims, front to back, rubbers. It should be virtually solid. Best done with the basket in your hand tbh but a quick check will confirm whether you need to dismantle the clutch. If you do, fit a new circlip, don’t reuse the old one.

I recently sold a good 550 basket to another member who’s basket was knackered, I may have another, not sure. I have quite a few 550 clutches lying about. Oh and if you look for a new one don’t think the 500 basket will fit, looks almost the same but it won’t fit. Oddly the damper rubbers will but that involves some major surgery of the basket and it’s not for the faint hearted.

[McCabe-Thiele (Ted)]

Not sure if he still makes them, a former member here Max made a batch of cushions for the clutch baskets he also supplied either a repair kit using screws to replace the original rivets or would  offer a fitting service. He is on eBay, I'll post the link to his shop when I'm on my PC.