Honda-SOHC

Hello,
I bought a pair of coils from EBay for £37! They’re bound not to work!
I’ve just fitted them. They’re working fine so far after an ‘extensive’ 25 mile test.
The only problem is (as someone else here stated) the mounting holes are 90mm apart and the  standard fitting on my 550k3 is 100mm apart so you need to make up two little steel brackets. Measurements, 11mm wide, 28mm long with two 6.5mm holes with centres 10mm apart and 9mm from each end. Also as they have male spade connectors you have to make up 4 wires (2x female spade to male bullet black with white stripe and 2x female spade to female bullet one blue and one yellow). They need to be about 250mm long. I don’t think the coil connections are polarised so I just wired them the same way as each other.  I suppose we’ll see how long they last.
I was also quite pleased I did this as the yellow wire connection just fell apart and was due to fail. Good luck with it.

Thanks both for your replies,
Yes I have copper washers on the cam cover bolts and aluminium washers on the cam end cover brackets. Mind you Ali washers were harder to come by than expected. also I’ve had to put in extra O rings at the end of the cam cover dowels to get them to seal off. Another reason why I thought I might be over pressured. 
I think you’re right I need to take the pump off and have a proper look.

Thank you K2-K6 and Odd Job,
Right thanks I'll replace those copper ones below the bracket with aluminium.
I'll also check the pressure relief valve on the oil pump. Can I do this without draining the oil?
Are there any disintegrating O rings I need if I check the relief valve?

Thanks again for all your suggestions.

Thanks All for your input.
Yes I'll check the pressure coming out of the breather hole to get a feel for whether its pressurising. Good idea thank you also the ideas with the oil sucking or blowing. If it is pressurising what might cause that? I have replaced all the valve seals and have the valves recut and reground professionally.
The cam end cover bolt currently has two copper washers on it one above the bracket between bolt and bracket and one between the bracket and the head. I might try replacing the one between the bracket and head with an aluminium one. They both tighten down nicely although the leak only seems to be coming from the left side one.
I've tried various Viton (higher temp. spec than Nitrile) O rings in the cam end cover in an attempt not to pay the huge price for Honda ones but have given up and coughed up for ones from David Silver. I'll fit those in the next few days. Fingers crossed.
I have tried to use copper washers on the bolts holding the main cam cover down in order to seal them. It seems to be working so far. I just wasn't expecting to see these leak oil.
Thanks again for your ideas. 

Hello Fellow Owners/ sufferers,
I have been having a nightmare trying to get my nut and bolt rebuild CB550K3 to run properly. However, I have solved it and wanted to share the solution with you all as I was searching for the answer on this forum and the other SOHC forum. At this point I have to say that I had ultrasonically cleaned the carbs, cleared out the float breather holes (in the brass rod out of the side of each carb), checked all internal petrol and air ways were clear and set the float heights with carbs on their sides at 14.5mm. I have stock exhausts (which are little more free breathing than they should be due to baffle disintegration) and standard air box and filter (which is new at vast expense).
1. The first problem was that I couldn't get it to run on all four cylinders at all until having fired on two for a good few minutes.  It would finally start to behave and in the end fire on all four. The main mystery was that it was 1 and 2 that didn't seem to be firing and that meant it couldn't be ignition as 1 and 4 share points and coil and 2 and 3 share the other one. After trying all sorts and taking off the carbs numerous times I finally realised that the choke flaps weren't quite closing on full choke on 1 and 2. They had a gap of about 1mm at the bottom and I thought that would be OK but it wasn't. Readjusting the flaps by loosening the two screws holding them to the bar and then retightening them with he flap fully closed allowed them to fully close with no gap at all. This completely solved the cold starting problem. I think its because the choke doesn't simply just block the air from coming in. I think it allows a vacuum somewhere in the carb to build up and draw more petrol through and with a 1mm gap this vacuum is not building up so not giving the richer mixture to 1 and 2 in this case.

2. The second problem was that the bike would not rev past about 4500rpm. Up to this point in the rev range the bike behaved beautifully. I had originally replaced all jets (apart from the one you have to pull out manually), tubes and needles with the Keyster carb kits. In an attempt to solve problem No.1 I had replaced the Keyster needles with the original Honda ones which had no effect on problem No.1. I now had Keyster main jets (90) and emulsifier tubes with the Original Honda needles (set to the middle position). In an attempt to solve the 'not revving out' problem I decided to try taking out the air filter. It ran a lot worse but basically behaved the in the same way. So I reckoned the bike was running lean even with the air filter installed. I didn't do a plug chop at this point which may have confirmed my suspicions. Anyway, having read lots of different opinions about the Keyster kits I decided to try to measure the size of the Keyster main jet and compare it to the Honda original using a copper multicore wire that I twisted to be 0.9mm across, copper being softer than the brass jet. Note that a 90 jet has a orifice 0.9mm and a 100 jet has an orifice of 1mm etc. I have to say the Keyster was a tad tighter than the original Honda meaning it may have been marginally smaller. Was this significant? I'm not sure really. Obviously changing jets from 90 to 100 is only a 0.1mm change so maybe this difference in feel of the friction between wire and jet is a significant difference. The jury is still out on that one. However, when I came to compare the emulsifier tube from the Keyster kit to the Honda one there was a significant difference in the pattern of holes drilled in the sides of the tube. The original Honda tube has three pairs of holes at the main jet end of the tube, a pair of holes at right angles half way up the tube and a single pair of holes at the top of the tube. The Keyster tube has almost the opposite. It has a single pair of holes at the main jet end of the tube a gap and then 4 pairs of holes at the top half of the tube. There is no pair of holes at right angles half way up the tube. So does any of this matter? Well, I replaced the Keyster main jets and emulsifier tubes with the original Honda ones. The bike now revs out nicely, no hesitation or flat spot at all so problem solved. The moral of the story is keep your old jets, tubes etc. until you know the new stuff you're replacing it with is OK. I have to say while some have had no problem with Keyster kits I would not use them again. This has taken a very long time and a lot of frustration to solve. I hope this helps someone in the future.