CB750F2 .... silk purse from a sows ear.

[hairygit]

A 3 legged puller wont stand a chance getting the rotor off, you need a tool (or a bolt of the correct thread) that screws into the rotor body, you will see it has a thread in it for that purpose, which screws in against the crank itself and pushes the rotor off. As regards the loom, if you can afford it and can get one, best plan with something this old that already has issues.

[SumpMagnet]

Oh cool...so I just undo the bolt on the end, and screw in a longer one to pop it off. My old Guzzi used a similar approach, only you had to put a 6mm rod in and then screw the original bolt back in to pop the alternator off.

https://www.davidsilverspares.co.uk/CB750F2-(Single-overhead-cam)/part_326959/

It's £95 by the time the government has had it's 20% ... so it might be on the Christmas present list.....

[hairygit]

No, the extractor is a larger thread than the one that holds the rotor to the crank. If you look inside the rotor after removing the crank bolt you will see the thread inside the actual rotor. The extractor bolt screws into the larger thread in the rotor, and when it hits the end of the crank it uses the crank to force the rotor off.

[hairygit]

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!

[petermigreen]

Oh cool...so I just undo the bolt on the end, and screw in a longer one to pop it off. My old Guzzi used a similar approach, only you had to put a 6mm rod in and then screw the original bolt back in to pop the alternator off.

https://www.davidsilverspares.co.uk/CB750F2-(Single-overhead-cam)/part_326959/

It's £95 by the time the government has had it's 20% ... so it might be on the Christmas present list.....

Plus postage

[SumpMagnet]

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

[Trigger]

Contact a member Paul G, i thick he bought a few bolts to get the fly wheel off.

If you need the valve seat done, do not let any engineer cut them. They like to be ground 
And if the valve guides need replacing, then you will need the head skimmed. All this will need doing after any paint .

[SumpMagnet]

Trigger...thanks for that. I definitely want the valve seats done, as they are not sealing like they should. It also seems silly NOT to swap out the valve guides while everything is torn down. Of course...they may be perfectly fine....but I have had several people tell me the exhaust valves are poor on these motors. With unknown mileage on the motor I don;t want to leave things that could result in a smokey, rattley motor.

Also...I would have painted the head AFTER I got the work done. I suppose it's better to paint then skim, so you don't have to worry about paint getting in the way and you know the surface won;t have paint ridges to cause sealing issues. Need a guy to do the work who won't scratch the paint

[Trigger]

Contact a member Paul G, i thick he bought a few bolts to get the fly wheel off.

If you need the valve seat done, do not let any engineer cut them. They like to be ground 
And if the valve guides need replacing, then you will need the head skimmed. All this will need doing after any paint .

Weird that in respect that the original tools in the front of the manual show cutters not the grinding machine we ended up using, never thought of that before.

That is a bit strange as was never sent cutters from Honda, only the grinding machine which i still have 

I have seen engineers try to use a Serdi valve machine and make a right mess 

[SumpMagnet]

Been a slow progress week.....so no pretty pictures to show for a few days.

Not been idle...but the pace has slowed.

I needed to go back througfh the bits pile, bag up, store and tidy the stuff I had dismantled. The cams were wrapped in clean rags, given an oil bath and then taped up in some thick plastic bags. Same for the cam towers, the head and the barrels. All the nuts and bolts have been freezer bagged, labelled and boxed up. It's made things a bit easier in terms of storage!

All the engine covers have been removed and I plan a visit to the family in a week or so. Dad has a stock of US spec paint stripper which I plan to raid. Stripper that still has hte old magic ingredient that strips paint...which apparantly is far too dangerous for us to use nowadays. He also has a small blasting cabinet. Going to take some sample parts down ( they are in Somerset...I'm in London....nice and local eh? ) and see how well I can clean them up.

Got to go out of town next week.....so I got to leave it alone for a whole week ...and just shop for bits

[SumpMagnet]

Back after a weeks hoiliday, and straight out to the shed to get the next steps done

While I was away, a package had arrived from Paul G. Many thanks!!!! It contained one M20 x 1.5 bolt.... and with just a short bit of spannering, this was the end result:



Popped off like a beauty. The starter motor gear parted as I slid the rotor off. Nice.

Not so nice was the 20 minutes I spent in the dirt and spider webs under the bench looking for the spring, little metal sleeve and roller that decided they would make a break for freedom. God...it's nasty under there! The bench I mean. Needed a sit down and a strong cup of tea once the parts were all cleaned of grit, swarf and I don't know what. Now for the fun task of putting them back in.

Some surface rust on the back of the rotor, but that cleaned up fairly easily. The rubber seal on the starter gear was rock hard....so don;t know if that needs replacing. At least the crank taper was clean with no signs of nastiness there.

Now I can get on to the other side of the motor and start pulling the clutch side apart.

Engine work wise....I now need to find someone to do the head/valve work I know needs doing. I have had some suggestions....all of which pointed the same way. To a certain very busy, overworked specialist with far too much work on. Plucking up the courage to ask....

Have not opened up the oil pump area of seen the crank bearings/shells yet....but want to try plastigauge and such myself. As long as the crank bearing surfaces are not scored or marked. If that is the case...then it's work beyond my meagre skills and will mean going back to the credit card/expert route.

Really am getting close to the part where I can start putting things together and painting...the parts I really like. Also.....the spending will commence soon. Normally I am as tight as a stereotypical Scotsman when it comes to cracking the combiination lock and waiting for the time-lock to tick over so the wallet can open. Once I have got it out from under the sleeping leopard that guards the Piranha tank I keep it in. But I am actually looking forward to buying shiny things to make her pretty again.

[Spitfire]

Good that you are cracking on with it, though it's making me feel guilty as my pile of F2 bits are still sitting there on the shelves in the garage.

Cheers

Dennis

[SumpMagnet]

Took the plunge today to have a look what lay within the sump....gulp.

Popped the drain plug and caught the stuff that came out. I'll call it 'oil' ..... but that's a pretty flexible description. Lets see....

colour..bleurgh. I think British Leyland painted Allegros this colour.

It still felt like oil, but it was pretty thick and had a fair amount of sludge. I passed it through a cloth looking for big bits, but nothing found. So far...so good.

Next, I tipped the motor up and took the sump pan off.

More sludge, thick  gooey and grey looking. It looked like instant gasket...but when I squished it...it was just grey/white sludge and not rubbery.

The filter mesh looked OK with just a few bits of muck in there.

Not sure what it is, but it wasn't metal and crumbled when rubbed between the fingers. Felt like gasket shavings. OK in my view...and nothing scary.

Lastly...I took the sump pan, and poured in a slug of white spirit to dissolve the sludge. Partly to clean it...and partly to see if it contained anything untoward. After it had been left and then scrubbbed with an old toothbrush, I dunked a magnet in there and swilled it around a bit. Picked up a very fine metallic 'sludge' which you can see on the magnet there.

PC hard drives come with a lovely magnet in them, so whenever I scrap one, I keep the magnet for this kind of job

So....pretty boring really. In a good way! Of course, the motor spent a week lying on it's side while my failed attempt at engine removal / finger removal healed and bits could have got elsewhere, but hte main thing is I have not found gear teeth, bearing fragments or piston rings lurking down here.

Less good is the chewed up state of the screw in the end of what I presume is selector drum. It's chewed to hell. I hope I do not need to undo it.......Also there is what looks like the signs of previous crankcase seperation just behind the large bearing. Looks awfully like a screwdriver applied to break the seal. Hopew not....but that's what it looks like. Ho hum.

[hairygit]

More good news, even though the Haynes manual tells you to remove that chewed screw and dismantle the plate and pins, I have NEVER done it on a 750 motor, there's no reason to!

[K2-K6]

Doesn't look too bad really at first approach.

Those four crosshead screws on gearbox bearing retainer are usually chewed if it's been apart but they look newer, so possibly been replaced as people generally butcher them.

The lever point by the bearing ordinarily come about either because someone hasn't taken all of the bolts out and tried to get it split,  or jacking up one side/end of the cases and getting them pinched on locating dowels. It suggests it's definitely been apart though.

That "sludge/paste" in the oil is what remains of the oil viscosity additive package that has broken down and dropped out of suspension in the oil.  10/40 multigrade oil is only ever a true 10viscosity and acts/simulates 40 when hot by use of the polymers used to give a pumped resistance equating to the higher number.  That's just the remnants of that chemistry laying around. 

Not scary so far,  just normal stuff. Be interesting to see as you get further inside.