Honda-SOHC

On the original bars there is a central slot between the serrations for the wires to exit. On the ends of the bars, someway in there should also be a slot for the wires to enter the bars but next to the slot there should also be a small hole, this is for the peg inside the switch to fit into, this positions the switch properly on the handlebars and also stops it spinning on the bars. The bars themselves should also have 2 punch marks next to outside edge of the serrations, these should be aligned with the gap between the clamp and the yoke so the bars sit at the correct angle.

Just in case you didn't know that Ted. AFAIK all Hondas have these punch marks, same as the ones on the pedals and pivot pins on the brakes.

Try these Ted, https://www.davidsilverspares.co.uk/CB550F2-SUPER-SPORT-1977/part_188996/

£5 plus P&P, seems reasonable considering what NRP want for one.

If DS are selling CB550F bars with the holes make sure they are UK bars not USA bars before ordering.

Yeah, I've got a NOS one in the loft. I'll pop up and measure it.

Another little tip. If you would like to fit genuine Honda screws in your handlebar switchgear (genuine ones tend to have a captive spring washer fitted so you don't lose it) however Honda fitted silver screws in a black switch but later hanged them to black so they didn't stand out. To find the later type then use the same system as the bolts. 93892-0502007 for instance is a 5mm JIS screw, 20mm long with a captive spring washer in black. The 550F for instance uses 4 x 25mm screws and 1 x 32mm, these are all available in black and IMO look better as a result. I must admit they ain't cheap though but on a level with the normal silver ones.

Use flanged 8mm headed bolts from modern Hondas on all casings. The flange spreads the load and stops the bolt digging into the alloy.

As for other bolts, if it had flanged originally then replace with flanged, engine bolts are often flanged, especially the ones on the top of the casing. If you can't find flanged in the correct size use a washer underneath the head so the nut doesn't dig in as it tightens.

Engine hanger bolts tend not to be flanged, use normal bolts for those if you like but make sure you also fit a washer under the head and a washer and spring washer underneath the nut. Also grease them well to stop them binding/rusting into the frame hole. Especially critical on the ones going through the crankcases, like those under the engine and at the front of the engine.

If fitting stainless then try and source bolts which use the correct size head if at all possible, don't forget as well that Honda had a nasty habit of changing the thread pitch on some bolts, not a huge problem where you're also replacing the nut but bolts which go into threaded holes for instance need to be checked for thread pitch, 6mm bolts/screws tend to be 1.00 pitch, 8mm are usually 1.25 pitch but some 10mm bolts are 1.5 pitch not the 1.75 that's usually supplied, they are called metric fine bolts. Same go for nuts fitting to studs, check pitch before ordering. Rear sprocket nuts for instance are 1.5 pitch not 1.75. Bottom fork yokes are metric fine as are caliper bolts.

I use https://www.stainlessmiddleton.co.uk/ for my stainless as they are highly polished with no writing on top of the bolt head, he also does 12mm headed 8mm bolts instead of the more normal 13mm head. Same for 10mm, he also does 14mm headed bolts instead of the usual 17mm. Don't forget, if in doubt measure pitch first or ask for advise on here.

You can see the modern Honda bolts used in this pic, on the generator cover and also on the camshaft cover.