Partially Restored 74 CB550

[davidcumbria]

Have done this now and thought I’d record a few comments based on my experience and forum research.

 I used a bulb in series with the points with a loose battery to determine the opening point since the loom is not in place yet, as seen in Millyard video. Problem was my test bub was too high a wattage and I ended up partially melting the insulation washer at the contact feed. Good job I had bought some nos FEW brand breakers on eBay. These are Japanese made and seem well constructed - better than the ones I took out. They seem to be used as oem by Suzuki and Kawasaki. Anyway lesson learned and I used a 2W bulb after that with no problem.

When I set the points gap to 0.35mm with new points ( ie middle of the 0.3 to 0.4MM, 12 to 16 thou range ) I ran out of timing adjustment. Have since learned this was probably due to the base plate having some slop in its mountings which can be eliminated by shimming the mount with a piece of sacrificial feeler gauge or by lightly tapping the mounting flanges inward. Otherwise as I found getting the timing and gap in range is a hit and miss affair as the back plate moves when tightened down. There is also some sideways slop in the 2/3 mini backplate. Good maxim is points gap affects timing - timing doesn’t affect points gap. I got there in the end by sufficient random efforts but not happy that my points gap ended up at the top end of the range.

Points gap sets dwell ( the angular duration that the points are closed to charge the primary coil) and so ideally gap is as small as possible. It’s arguably not so critical on sohc points set up because the dwell is already very generous compared with say a V8. I have now bought a Gunson auto ranger analogue dwell meter which are reckoned to be better  than the newer digital ones. . The theoretical correct setting is 23- 24 degrees on 8 cylinder meter setting ( wasted spark issue ) but because of tolerances between points/ back plates / cams  it is more important is get the dwell on both sets of points the same, and to dynamically check timing at the same time. Once set with new points you can just keep readjusting back to this point on the meter as the contacts and cam heel wear. Full advance is when the ll  mark lines up and should be at 2500 rpm.

This a very good read.
https://motorcycleproject.com/text/sohcign.html

 I’ll report back on the dynamic set up when I get the bike running which shouldn’t be too long now. Wrestled the headers on for my 4into one yesterday - why weren’t we born with 3 hands !

[Oddjob]

Many many moons ago I bought a Gunson Dwell meter for a car I was tuning. Like Mike Nixon I decided the best way to setup the Dwell on my 500 was to fit a new set of points, gap them as good as I could, using TEC points, then see what the Dwell read on the meter. As it turned out it was 48 iirc, not wanting to forget this I scribed it onto the meters face plate, I have since found out that the official Dwell angle listed by Honda was 50 degrees for the 500, so I was very close.

In hindsight what I should have done was retest the setting using the Honda equipment when I had access to it in the trade but tbh the bike ran great at 48 degrees and was the same engine that would tick over at 5-600 rpm. Interesting to read Mike saying no more than 1100 rpm for timing when some members are advising setting the tick over at 1200 rpm, I always followed the Honda setting of 1000 rpm as the optimum setting. Faster tick overs just disguise engine faults in my experience, not saying you shouldn’t do this btw, better to have the engine ticking over smoothly than banging it’s nuts off, just as long as you are aware of the faults like a slack primary chain and get round to fixing it before it really becomes a problem.

[McCabe-Thiele (Ted)]

Interesting read Dave - only thing I would mention is a higher idle speed will increase flow to the camshaft.

[Seabeowner]

Just to add the owners manual for the 500s and 550K3 both specify setting for points gap at 0.3-0.4mm. I wonder what the dwell variation is between 0.3 and 0.4.
And the two cam assemblies numbers for Hitachi and Toyo are the same for 500 and 550K3, so you would think the dwell is the same.
It's on page 181 of my manual and Honda are capable of making one or two or three mistakes.

[Oddjob]

500k3 or all 500s though Seabeowner? The coils are the same as well I'd imagine, in fact there are a great deal of the same parts fitted to both the K3 and the 550F2, however the intake system was completely different, the fuel air ratio was different, the K3 was made to fit into environmental policies in force at the time, the 500 and 550Fs weren't. I tend to ignore the 500K3 as it's like a unicorn, if you see one you are lucky.

[Bryanj]

Or from the workshop point of view unlucky, damn pd carbs

[McCabe-Thiele (Ted)]

I used a dwell gauge since the mid 1960s when I learnt it was a more accurate way if setting contact breakers.
IIRC it was a multi meter type unit - I don't think it was a particularly expensive item at the time.

Truth is members here will follow the advice of those with a proven track record or look to reinforce existing personal bias in terms of solutions & outcome.

Interestingly one issue that crops up regularly is bleeding front brakes. It appears that some members  have never had a problem even when using quite  different methods to reach the same outcome.  I pump fluid up using a large syringe at the caliper end until fluid appears at the master cylinder reservoir. It works for me but not for some. I don't think this makes my method invalid it just means for some it fails to work for unidentified reasons.

[deltarider]

They were bloody expensive here. Usually they doubled as Tach/Dwell meters. Some had more functions. I have two analogue ones that each cost a week salary in the 70s. Now you can find them cheap on ebay. You'd better not use the extra functions some had. Readings Ohms wasn't as good as a cheap digital meter now is, and the accuracy of the Amps function was a joke.

[McCabe-Thiele (Ted)]

They were bloody expensive here. Usually they doubled as Tach/Dwell meters. Some had more functions. I have two analogue ones that each cost a week salary in the 70s. Now you can find them cheap on ebay. You'd better not use the extra functions some had. Readings Ohms wasn't as good as a cheap digital meter now is, and the accuracy of the Amps function was a joke.

Where is here,  not the UK?

[Bryanj]

I proved to an apprentice that i could be as accurate with a feeler gauge as he was with a dwell box, it is down to experience and practice.
All the 500/550 are not the same, there are at least 2 different advancers with different advance curves, when i was in the trade i NEVER had a bad set of daichi contacts OR condenser, now its different due to change of factory and QC.
Delta you are very pedantic that you are always right, you say dont fit fuel filters, i used them for years and again never once had a problem.
We all have our own ways of doing things, points gap is specified as 0.35mm or 14 thou and i bought feeler sets with those sizes specifically, i also never use a strobe only do static timing and again never a problem, there is also a fixation about not using rtv gasket, its fine WHEN USED VERY THINLY.
More and more we could go on about, i started working on bikes for a living in 1975, part time from 1972 and have done most Japanese, most English and have even worked on the rarest Ducati the 750ss, nice ride by the way,

[davidcumbria]

After this fascinating debate back to something more prosaic,I’m afraid.  I took photos when disconnecting all the  connections in the headlight but find them difficult to follow in reverse order. I have never been this deep into bike electrics before. I have got the wiring diagram and understand how it shows the connectors and where the loom ends. I have  a strong feeling the wiring has been modified - there are some snap connectors in there.  There were lots of unconnected bullets from the pattern switchgear.

So any tips on a good process to get it all connected up again. I assume I have to shove all  the loom, switchgear, tachometer/ speedo, idiot lights leads into the headlight shell first and then try to make the connections. This is going to take awhile….

I have also found the section in Teds thread that has some useful stuff

http://www.sohc.co.uk/index.php/topic,28541.540.html

[Johnny4428]

Sometimes you can make the connections before packing into headlight shell. More room to work.

[Bryanj]

David, as far as i know there is only one wire that is not connected colour to colour and that is one from the rh switchgear and i cant remember if it is the power from fuse box or the power back fot lights

[Oddjob]

Dave, if the handlebar switches are pattern it's well known that some use different coloured wires to the Honda switches, you could look inside the switchgear and make notes of what colour wires are used to connect to the horn for instance. There are at least one wire used by Honda where the colour of the wire is wrong, to get around that Honda used small tubes of the correct colour to connect to next to the connector. Spotted one the other day on the brown/blue wire coming out of the kill switch switchgear, it has a yellow tube on the wire, most likely meaning it's to be connected to the brown/yellow instead. There's another by the horn IIRC.

On PDI the first job we did was remove the headlight and connect all the wires up, none were connected by Honda, just a huge mess of spaghetti when you took off the headlight, good job I wasn't colour blind, getting some of the headlights back in afterwards was sometimes hard, the CX500 was a bitch to do. Make a sort of doughnut shape with the wires so the bulb holder can fit inside the hole, easier on the CB550 than on the 500 as the handlebar switches don't connect in the headlight but down by the coils so far less in the bowl than the 500.

[Bryanj]

As Ken said most Hondas were shipped with handlebars not fitted but switches were on bars.
Ken was also correct about the brown/blue/ yellow thing, i just couldnt rememer the colours