Honda-SOHC

I have a kh125, have had it for ages. Its never run. Previous owner couldnt get it running. Owner before that rebuilt it.
I tried everything, then laid it up for a year.
I just stripped engine, rebuilt it and am trying again but it still wont run!
 Carb is spotless.
Rebored, new piston, rings, bearings and seals.
Got good spark (but no battery power, shouldnt matter).
Cant see any way to adjust timing except by altering points gap.
Ive had the rotary disc valve in both ways round.
Got cood compression and clean posh petrol. Petrol is getting to carb, plug is getting wet but might just be oil. Ive tried a bit of fuel down the plug hole and ive tried brake cleaner squirted in the carb lol.

I just dont understand why it wont run!

Anyone know anything about kh/ke 100/125?

Im at the stage now where I just want to set fire to it.

As title.
valve seals seem ok, all dry except number 4 which had lots of oil in the bore. So I know why its smoking on start up but dont know why there is oil in the bore.
The oil seems to be coming from around the stud and leaking past the head gasket. Its number 13 stud in the tightening order. It doesnt have an o ring so im guessing there shouldnt be oil here to start with? With the head off its still full of oil around that stud so is it just going to be getting past the nut and washer? Can oil come up around this stud? Can it drain away from this stud?
I can see no obvious problems with any seating surface and all torques were good.

I just got my cb750f1 running again. Runs nice.
Floats set at 26mm.
One overflow leaks a bit though but it only leaks when you turn the engine off. A few seconds atfer switching off it burps about a thimble full of fuel out of one overflow. It doesnt overflow at any other times, just one short discharge a few seconds after killing the ignition.

Ive just been through the carbs, cleaned and checked and all seems good.

Any thoughts?

Now it seems my wiring is sorted I need to look at the breathers. These weren't connected when I took it apart.
It has the can bolted to the underside on the battery box. This has 3 connectors.
There is a breather from the rocker cover, one from the case and one (or 2, ill have to check) on oil tank.

How do these all connect?

Thanks.

While my F1 is apart i thought id freshen up the top end seals.
Ive not run it for nearly 3 years but it always used to smoke on start up if it hadnt been started in a few days.
I had previously had wet sumping issues so just took the pump out and the valves still fine.

So while the engine is out I figurer I should do the stem seals and I believe there are puck seals under the cam holders?

What im wondering though is are all the seals you can get the same make? I can get a complete gasket set which I assume has these seals or I can get seperate valve stem seals from DS.
Any other options?
Dont want to waste time and money fitting bad quality seals considering the engine has to come out if they leak again.

thanks.

Im a bit confused about some of the pipework on my 76 cb750 F1.

first, the clear breather from the rocker cover, where does this go to?

Second, my bike has the breather can under the battery, but its not connected to anything. My parts book suggests its linked to the air box, at the top, but my air box has no connection for it. My air box has cb750F written on it so i guess its the right one.

Third, my carbs dont have the pipes on the breather/balance outlets on carbs 2/3.
Carb 1 is linked to carb 2 with teh short pipe, 3/4 are connected too, but teh 90 degree outlets in the middle of carbs 2 and 3 have no pipes.
Are these important? Do they connect, or just vent to atmosphere?

Fourth, there is a pipe underneath the tank, i assume this is the tank vent.
It comes back as far as teh rubber tank hold down but no further. Should this be longer and vent down by the swingarm like the carb overflows?

Thanks.

First ride of the 750 today, took it for MOT and it passed.

However, there were 'issues' LOL.

Bike stutters, power comes in fits and starts. It did smooth out a little after a while, but not great.

Then, it cut out and wouldnt re-start. It did this a couple of times, cutting out dead when pulling up to a junction.
It would re-start, but only with a bit of choke, then off choke imediately as it doesnt like running on choke.

First thing felt like it was lean, or maybe ignition.

Then, stopped for petrol and it wouldnt re-start. Eventualy drained the battery. There is no way this bike will start on the kickstart, but normaly starts straight away on the starter.

Got it trailored home, pulled a plug, and its properly sooted up. Didnt get a good run on the bike so hard to tell, but my guess is its fouling up the plugs to the point where there not firing.

Air filter is suspect, ill remove it for now, see if that helps, but ill look into the carbs again.

Do you think the dodgy power thing could be running rich?, plugs fouling? It did feel a bit like that.


When i went over the carbs i noticed i have 2 different types of emulsion tubes. One set where the row of 4 holes are all the same, and another set where the bottom 2 holes are a fair bit smaller than the top two.
Any idea which ones my 750F1 should have?

As the chains are a bit noisy, and the starter clutch chatters, the AA man thought it had slipped the timing chain. I find this highly unlikely though. I think he just didnt want to know.

Ill look into the starter clutch though.

Just a quick question about plugs.

First of i have dr8EA in it at the moment, but i also have some of the recomended DR8ES.

Whats the difference?

Also, long or short plugs? My factory manual suggests both were used over the years but it doesnt say which ones for the F engine (presuming my engine is origional, engine number starts 25 i think, can check if needed.

It has long plugs in it at the moment, if these were wrong would they be clipping the pistons?

Its a 1976 F but who knows whats been changed.