Honda-SOHC

When you assembled the crankcase halves is it possible that an excess of Hondabond could have entered somewhere to lead to this problem? Could the crank seals be somehow causing the extra binding if they have distorted?

I'm assuming you have not fitted the block yet.

I think you will have to split the cases again to investigate further.

I have considered if the seals were the problem, but fitted well and tightening only happens on final torque of mains bolts.

I will try easing them off and re torquing.

You can turn the crank but do need a spanner on the alternator bolt.

Wondering if I am being too cautious.

Can you normally turn by hand on rotor without pistons fitted?

Does the crank have that free movement feel if you make a very small rocking action with the crank?

Do you have any doubts that the crankcase halves were a factory pair?

I will check for end float.

Pretty sure halves original

Im in the process of reassembling the engine on my 75 CB500K1 basket case that came already stripped.

Crankshaft checked for wear which was minor and well within spec.

Minor marks to crank main shells on 1 and 5 but replaced with new genuine Honda Green shells in line with calculations of housing and journal.

Checked with Plastiguage and all mains came out at 2 thou.

Reassembled with top case down and inserting primary shaft after cases together.

Bearings well oiled and fitted evenly.

Cases closed up easily with light taps with rubber mallet and gradually torqued up as per recommended order but on final torque crank becomes more difficult to turn.

It turns with a spanner on the alternator bolt but feels tighter to turn than I would expect.

I have rebuilt 3 CB750 enfines without this issue.

I have just checked and force required to turn crank is 9 lb ft.

Removed primary shaft and does not change.

Would be interested to hear if any similar issues .

Thanks

Martin

If anyone has the above available would be interested in buying.

A complete primary shaft would be ok as long as sprocket teeth are ok

Its the spring plate that holds main jet.

Let me know price and condition.

Thanks

Martin

Make sure you leave the sump & oil filter off off it's pretty maneagable just as the crankcase halves, plenty of space to fit the block upwards afterwards.

I used a piece of cardboard in the shape of the sump held in place with a couple of bolts to keep the dog hairs out until I fitted the sump etc.

Thanks Ted

Started to reassemble my CB500K1 engine and finding just the bottom end quite a lump to handle.

I wanted to double check that it is possible to reassemble everything in the frame once the crank case halves are together and installed and whether anyone else has tried.

I have a motorbike lift which means it is easier to work on at comfortable height.

I have rebuilt a number of CB750 sohc engines and no option other than to assemble up to cam cover, but I was a few years younger then 

The return spring on my 500 K1 was missing. I eventually sourced the correct return spring for my 500 the spring sits on the outside of the frame/swing arm as you have identified.

There is a photo by Simon (SPR) showing it fitted.
If link works its this:-  http://www.sohc.co.uk/index.php/topic,28739.0.html

Thanks Ted

Just wondered if any update on repro to match original availability?

I lashed out on new original down pipes and collector but waiting for silencer availability before fitting