Honda-SOHC

Just rebuilding my Master Cylinder and have a ? I am sure I have seen this ? before somewhere but cant find it !!

There are two holes in the base of the reservoir. One is clear and reatively large the other is my problem. Is it a very small hole or what. I tried poking with the end of a safety pin but hesitant to get more agreesive until I know what it should be like.

Hopefully picture is self explanatory

Thought you folks might like to see how my project is progressing.

Bought this K0 500 1971 (US Import) rom D&K in Staffs in October as had been looking for aproject for a while. Why this one?

1) I got it at a decent price because engine was totally seized (i think they'd had a go at it but couldnt free it)
2) The mileage was indicated at 13,000 and looking at the condition of the frame, chrome etc I was prepared to believe this was genuine. This was a really nice original US spec original bike. Only bad point no original HOnda 4-1 pipes.
3) I had no fear of an engine rebuild and reckoned cosmetic parts (new wheels, fenders, ...............would end up costing more than some engine bits).


So step 1 was to free off the engine. Tried all the "magic" potions - oil down the bore, rocking  in gear -- absolutely nothing. Ended up splitting cranks undoing big ends and trying to hammer each piston up. All I managed to do was 1/2 push out the liners. . So off to my local machine shop who pressed the pistons out, honed the bores and relapped the liners in.

Essentialy the seizure was just Pistons massively seized in their bores. No idea why as rest of engine really good. Just to make matters worse the gudgeon pins were so seized on the pistons I ended up milling half the piston away in our machine shop at work just to get the buggers out. See the attached picture

Measured the bores and they were still on "new" spec so now I was sure I had a genuine low mileager. In fact, inside the engine was really clean, no mucky oil or other horrors awaited me, again confirming my low mileage suspicions. So off to CMS for new pistons, pins and rings and to David Silver for Gasket set, set of oil seals, new big end shells .....

Engine rebuild took me about 3 week ends and went OK (with the usual 3 steps forward 2 back moments along the way). Long story about the timing chain and putting the front tensioner iin the wrong way round but that needs beer and a summer pub garden for the tale. Anyway got it all back together in the end and all goes round and round and up and down as intended

Once I had engine rebuilt I decided to take a big plunge and buy a set of CMS 4-1 aftermarket pipes as the original bike came with 2 OK but a bit battered MAC 2-1s. Big expense but I reckon I would always kick myself for not doing it. Obvioulsy haven't fitted yet but they look good quality.

Next job was a full carb rebuild as all the slides were also seized (dropping them in hot water freed them off a treat). As with rest of bike carbs were cosmetically really clean and no real horrors inside so did a full strip and clean (discovered that Cellulose thinners is really good for getting paint varnish off jets and bodies !!!) and treated them to all new O rings and a good clean up. Really pleased with how they ended up.

Next step was to decide how far to go with the rest of the project given that cosmetically the rest of the bike was very good with virtually no rust and even the frame showed only a small piece of surface rust around the main stand area and some scratches . In the end my view was that whilst the engine was out why not go for a full restore so I just pulled evertying down to a bare frame.

Next decision was powder coat or paint or what. Budget was by now getting a bit stretched (blame those CMS pipes !!) so given that the basic frame was so good decided just to see what a couple of coats of Hammerite rattle can gloss black would do and I was really pleased with the results.

Now I have pretty much all the bits cleaned and polished ready to go back together.

Jobs still to do

Rebuild Master Cylinder and Front Caliper
Get new Rubber fitted (don't fancy my chances on at least 20 year old rubber)
Bench sync carbs
Bolt it all back together
Press starter and see what happens !!!!!!

I will post more as I progress.

Just ordering some m8 nuts and Spring washers for my new exhaust brackets

Stupid ? But coarse or fine pitch

Thanks that's helpful ask it happens it's a us import but I guess you can't have everything 😄😄

I just did my frame, Stands and yokes using Hammerite Smooth rattle can and 2 coats and it's gone on really well with a good finish.

Having said that the frame and swing arm especially were in great condition already with only a couple of minor marks and small surface rust.

We'll see how it hold up but I will never use this baby in the wet anyway 

OK so let me confirm I have the process right

1) Slacken idle speed fully so it is not doing anything
2) Back out the mixture screws all the same at the same setting (Honda manual would suggest 1 turn)
3) Set up each carb with a 3mm drill in the slide to give a) bench sychronisation and b) a small amount of air to allow initial start
4) Fire it up (hopefully)
5) Balance carbs and fine tune idle mixture

AGGH I am stupid, when I stripped my engine for rebuild I forgot to note where the connectors go in the loom wire from the alternator. See the attached picture.

I also have a bit more confusion as the previous owner fiited an oil pressue gauge and I am going to revert to the Honda pressure switch mounted on top of the pump but I can't seem to locate the originl wire for it. Or is that what the "uknown" wires are in the picture.

Hopefully someone can help undo my stupidity of not taking more notes/pics before ripping in 

Just rebuilding my 500 K0 1971 (USA model)and have come across an electrical problem.

On the bike currently there is a brass small pipe coming off the top of the oil pump which is connected eventually in to a small diameter plastic tube that leads along with two wires to the front of the bike.

The tube and the wires have been snipped off by someone so I am unclear what happens here. I assume the small pipe went in to a pressure switch somehwhere but I can't see a switch anywhere. I further assume the two wires went originally to the oil pressure light on the "idiot" display.

I am now however even further confused as I can't see anything resembling this on the Honda parts list, what I do see however is an oil pressure switch mounted on the oil pump where my current small bore brass pipe connection goes.

As always I am sure there is a simple explanation and hope a fellow owner can shed some light on what I need to do. Obviously haveing a functional oil pressure light is kind of important!!!!

Look forward to the replies