Honda-SOHC

Welcome aboard

Seems to be the rule that US imports are better on the outside. I guess they don't decay the same as UK bikes.

Easiest thing to do is buy a bolt to do the job, M20x1.5 thread, say 60mm length, you can buy pullers on e-bay, but they rip you off price wise for what is basically a bolt!

Thanks for that

I went and had a look, and found something that fitted so I could check the thread size. Interestingly...the oil filter bolt is exactly the same thread. I wouldn't use it for hte job...but it was easy to measure it and it is indeed M20 x 1.5 and screws into the thread. With the bolt out, I could see exactly what you meant. I will go and hunt a bit to see what I can get hold of to do the job

Peter ...everything these days is plus postage

But....I know I need a bundle of things, and postage is one of those things that get easier to bear when you buy more.

Currently I am trying to find a diplomatic way of explaining to the missus that the head is going to need an overhaul, with new valve guides, probably new valves and having the seats looked at. Then there is the possible need to sort the cam carriers. Haven't looked at the crank yet....but I can already see £500 in bills

NgggggGGNGggnnsngngdfkgnfdgngngnnn.....

that was the noise I made when I started cleaning the rest of the odds and sods off the frame. A random set of 'earth' wires seem to have been bolted on, which may have been related to the electrical issues I was told about before I bought. Especially the one by the coils..

The loom is quite corroded on the terminals and the wires seem to have lost a lot of the flex they should have. It's also been unwrapped around the headstock...which is usually an area of concern with a loom. That's where wires tend to break internally leading to all sorts of interesting 'amusements'. I had a Moto Guzzi that did that to me. First the horn would sound on full lock...then the lights would go out when you turned....and finally when I went to swap the head bearings...I found it had been arcing across the ball bearings...which it was using to earth everything up front.

I might go crazy and buy a pattern loom from Dave Silver Spares so I can refit a good set of fresh unbroken wires for the inevitable electrical fault finding. That's one to bear in mind.

I have enough stuff off the motor to make it light enough to get up on thw workmate now...so I can crack on and strip the gearchange side. I also need to get a 3 leg puller.... I did have one, but it seems to have gone AWOL. No idea where...but I must have lent it out, and not got it back. That's the danger with tools you use rarely. I presume it's a 3 leg job to shift the rotor off the end of the crank...

I also need to consider what I am going to do with the alternator end cover. It's a bit scuffed and needs either replacing or refurbishing as it is pretty grotty. Someone has tried to repaint it black with matt paint. Now...the screws holding the fixed magnet on to the case are chewed. One certainly is already pretty rounded off and I doubt it will shift. Not sure how much bolt length is going to be left if I drill it....and I can't use heat

The jobs and parts list is growing....but the whole thing is breaking down into smaller and smaller assemblies, and the amount of 'bike' left is pretty reduced. Soon...I am actually going to have to start spending money and doing stuff other than taking it apart!

Those look so nice. .... getting all the little springs, washers and such plated and looking good as new just makes such a difference.

I guess the oil strainer is where all the missing bits of ...well...everything... ends up. Bits of crusty camchain tensioner, bitsof o-ring, bits of gasket goo, bits of whatever fell in there. At least I know the pump was still working as the top end was wet with dirty old oil, and the restrictor oil jets were clear. I hope.

At least with the head and barrels off...the motor has got to the point where I can lift it up onto the bench without risking injury.....so I can wrestle with the chewed screws on the side casing and open up the bottom end.

In the meantime, though.,....I found a use for that old seat. Makes a perfect place to park my backside while I was working on the top of the motor.

In the red corner........the CB750 lump.
In the blue corner ....... the ameteur mechanic.

After 2 falls and a submission....off with it's head was the cry! Yes....we got it done finally.

As always, these things have good and bad...so lets kick off with the bad.

1) I am not the first guy in here, and there was a little tell tale mark where someone had pried the head off before. Nothing serious...but of note for me.

2) The 4 bolts under the pucks were different. 2 were clearly replacements lacking the cast in washer and being fully threaded rather than a plain shank.



Now...the better stuff.....well...for me anyway!

The bores look really nice. No rust marks, no scoring and no discernable ridge at the top of the bore. I could see the horizontal hone marks but no evidence of vertical scoring or marks that looked anything like wear.



The o-rings around the studs were incredibly shot. One looked like a dead slug, and the others were crunchy. All will obviously want replacing. Going to need to clean out the muck around them too.



With the head on the bench,I did the old seal test.... pour a little fuel into each head..and see if it stays there. 2,3 and 4 were good as gold...but pot number 1 dribbled it's contents out through the exhaust valve. Not a surprise....I was told more than once on here that the exhaust valves were wear prone. The heads were pretty coked up, with quite a bit of carbon on the valves, but underneath things looked pretty good.



The barrels neweded a good clean from the oil I had dripped down there, mixed with some loose carbon...but once cleaned, things look nice. The pistons all look quite carboned up, but it all rubbed off pretty easily. Barrels off next, so I can check the piston skirts for wear. For now...I got some more oil soaking down the studs ready to lift the barrels tomorrow.

Thanks Trigger 😀

So far, I have o my got halfway down .. but the list is:

8 tappet inspection o rings
6 pucks
4 small ovrings for the oil jets and the other 2 oil holes.
O ring on cam chain tensioner plunger shaft

That's so far ..  the list will grow as I haven't reached the cam chain guides, guide wheels, crank oil seals, gearbox oil seals and suchlike

The cam chain tensioner rubber block is pretty rock hard, but I suspect that would mean replacing the whole shaft. The metal plate has very little wear though.

Dennis ...thanks for the tip. I have doused the areas I can with penetrating oil, and will let it sit for a day or two. I have undone all the bolts shown in the picture, so it is just gasket grip or something corroded in place. Could be time to start making some wooden wedges.....