Honda-SOHC

Hi all. Front hub polished and now on to rear hub. I need to replace the worn rear sprocket so thought I would remove the old one before I start polishing. I have flattened the tab washers, given the studs/nuts a good squirt of penetrating oil and left them to soak. However all 4 nuts seem seized solid. Before I resort to more destructive methods of removing the nuts are there any tricks/techniques to try? ‘76 550 K2

Hi all, can anyone point me in the direction of a testing approach for CB550 charging circuit. I have tested for voltage across the battery when the bike is running at about 3,500 rpm and Im getting just a smidge over 12 volts which is presumably the standing voltage across the battery. I have replaced the rectifier but not regulator; everything else is as I got the bike. I have had a trawl through hints and tips and the only thing I can find is a link which now leads to a game download site as opposed to a testing regime. Cheers, Mike

Hi all and a Happy New Year to you!

The next task for my '76 K2 550 is to check, remove and clean the advance retard mechanism. This has not been removed since I got the bike and in all likelihood has not been removed since 1976. To first take off the ignition points plate it looks as if I hold the larger nut still whilst undoing the 10mm bolt that screws into the end of the crankshaft. Before doing this I thought I would check with those that have done this before if there are any hints/tips for doing this as its clear that any cockup in the process could have dire consequences.

Any suggestions would be very much appreciated.

Cheers, Mike

I have the wiring harness back on the bike after repair and with the exception of a short somewhere in the idiot light console all seems good. I’m hoping to try and get the bike running at the weekend. I have set the points gaps and I’m now trying to do the static timing. 

I have noticed that the wires to the points seem to be the wrong way round on each contact breaker. Ie the blue and green wires are both attached to the correct contact breaker (1/4)  but the green is nearest the little nut as opposed to the blue (see picture). Does this matter?

Using a static timing light the timing for cylinders 1/4 seems spot on but there doesn’t seem to be enough adjustment in the sub-plate for cylinders 2/3 to get the light on with the marks lined up for 2/3. You can see from the photo that the base plate is rotated as far as it will go anti clockwise (the mounting screw at 7 o’clock is against the stop in the elongated slot). Is there something basic I have done wrong?

I am trying to repair my CB550 '76 K2 loom to get the bike running now the engine is back together & carbs, air cleaner etc. Eventually I will probably splash out on a new main loom as the one I have is pretty maimed. I am treating this as a learning opportunity; hoping I can get to the point where I understand how the bike works electrically, but I have a lot to learn. One thing is puzzling me. I understand that the '76 K2 wiring is unique in that it does not have the starter motor safety unit (SMSU) that the K1 has and has different connectors/handlebar switches to the later models (happy to be corrected if this isn't right). I have read that the SMSU works in conjunction with the clutch sensor and neutral sensor to prevent starting when in gear; according to the US SOHC forum in the '76 K2 the SMSU is replaced 'by a diode'. I think I have found the diode but I would be grateful if somebody could explain to me how this diode works with the clutch sensor and neutral switch. Can anyone explain or point me in the direction of something that explains this in simple language. Thanks

I have just received a Vesrah gasket set for my '76 K2 550 and I have been sorting through the pack of O rings to work out what is what. DS sticking packing tape over the parts list on the back didn't help. I have all the O rings sorted and Im left with one query. There are 3 O rings given as part number 91303-035-000. Two of these are for around the oil control valves where crank case joins the barrels. I cant for the life of me work out what the third one is for; can anyone tell me?

Also, I rather foolishly believed that the plastic sealing discs that go in the head and cover the head bolts would be in the kit. Not so and at £5 each a bit of a shock. I have found 4 of the old ones but the other 4 must have ended up in the bin. I assume its advisable not to reuse these old ones or work with a mixed set?

Whilst I was scrolling through cat videos on instagram this popped up: https://www.theadventurists.com/guides/monkey-run-morocco/

I got chatting to a biking mate about it and we thought we might give it a go. Has anyone done something like this and have any experiences to relate?

Whilst I was waiting for some paint to dry yesterday I had a rummage through the boxes of parts from the stripdown. Having read a few posts about the importance of getting the aircleaner correctly reassembled I thought I would check what aircleaner parts I do have and what are missing. Having checked the parts book for a K1, which I assume is the same as the K2 (please tell me if I am in error), I seem to be short of 4 parts:
1) Cover, Air Cleaner
2) Net Comp. Tool Tray
3) Tray, Tool
4) Spring, Cleaner Element

All of these seem to be as rare as hen's teeth and where available, very expensive, in another country a long way away, in poor condition.

How essential are these for the correct functioning of the aircleaning system?

I am many weeks away from needing to fit this but thought it good to research now.

Thanks to Ash and Deano for posting the parts books by the way.