Oil pressure issue / motor rebuild

[MrDavo]

The crank is definitely toast, all the main journals are scored. Ash has sourced me another, see earlier in the thread. I'm dropping the goosed one off with an engineer later to see if he can get the rotor bolt out after I get the points stud off.

The whole bike is that clean inside and out, with fresh pistons and bores as far as I can tell, it was apparently restored fully years ago and never used again. The failure was due to a kinked oil feed pipe, starving it of oil, again see earlier.

There is oil in the motor, I think its never managed to stay in long enough to start to get dirty. That said, I've found that one of the 3 oil pump dowels (with the o ring round it) is slightly distorted out of round, and not a great fit in its slot in the pump, I need to change it - CMS seem to have them. I'm guessing that that alone could be a cause of the low oil pressure, that combined with the kinked hose sealed the engine's fate.

[Bryanj]

The low pressure is simply the excess clearance on the mains, the real problem is what caused that

[MrDavo]

I think the mains were initially borked by the low oil pressure, caused by the kinked oil feed, it's a bit chicken and egg. Twice after start up the engine has suddenly found itself with no oil pressure at all for a few seconds since I got it as the cold oil hasn't fed the pump fast enough and the pump has found itself pumping fresh air. As the oil light stayed on at higher than expected revs on the first trip to the MOT, I assume whatever event killed the crank had already taken place.

Obviously once you have low oil pressure, it just makes itself worse. This is what I assume caused it, but I will check for a blockage in the oilways. There is an oil metering jet in the head, are there others? It is possible there is still something wrong, but I don't see what, the oil pump has drive and returns oil to the tank.

Another theory suggested is that the motor was completely  rebuilt (this is why its all so clean, it was vapour blasted like new inside as well as out, though not threads or gasket faces) then left for a long time  and was subsequently started up bone dry.

[Trigger]

The vapour blasting could explain why everything is toast. If any of the glass bead was left in any of the oil ways, it would of acted like grinding paste. Love to see what the inside of the oil pump looks like.

[Bryanj]

Takes quite a bit to remove all the white metal down to the copper, not just a couple of seconds

[Trigger]

Takes quite a bit to remove all the white metal down to the copper, not just a couple of seconds

He did say that he rode it to the MOT station, and most probably back.

[MrDavo]

A busy day Sunday. I polished the cam cover at last, stripped the carbs for an ultrasonic bath and the choke linkage for a replate.

I also removed and stripped the oil pump. The rotors and their fit together are like new, with slight scuffing, but the endplates are badly marked up. Some scratches in the body but not much. Trigger, are these toast or useable?

[Trigger]

Have not seen any used pump covers without slight marks but, it is hard to tell from a picture. Looks like something has been grinding away in there.

[MrDavo]

There's certainly been some grinding of swarf going on, I'm convinced the body and rotors will be OK, I was wondering if there was anything to be gained by finding new covers. As you say hard to judge from a photo, the scratches on the covers are quite deep.

If they're all a bit scratched up I might leave it, if you think they're a mess I'll look for newer ones.

[Trigger]

It is hard to measure the clearance. May be easier to find another pump and fit a new seal kit. just make sure that there is no glass bead left in any oil ways. It is a sod to clean and that is why I never vapour a engine.

[MrDavo]

I may get another pump for peace of mind, let me know when you get the seal kit in.

The pumps DK have for sale are unopened - they could be just as bad inside, so you are taking a punt unless they'll change them.

I just had a message to say the engineers have got the rotor and starter clutch off my old crank.

[bytio]

Ensure the 3 o rings are new, 2 large outer ones seen in the pic, plus the smaller one that the rotor shaft goes through ( a bit of a pig to get out) if these are not in good order oil will escape from pump and loose oil pressure


Sent from my iPhone using Tapatalk

[AshimotoK0]

As I said in PM I do have a spare pump but unsure of condition and model its off

[MrDavo]

As far as the pump goes, it all looks good in there as far as rotors and body go, I just don't know what is 'normal' for the scratching on the endplates. certainly the one they took apart in the Haynes manual looks just the same as mine inside. I was hoping Trigger could say 'good' or 'scrap' but I realise its not that simple from a photo.

A replacement may be wise, but a bit of a pig in a poke as far as condition goes. Maybe I should stick with what I've got, with new seals.

I am all too aware that I haven't yet found a definitive cause of why the mains failed, but that probably points back to the kinked feed hose, which would leave no clear evidence.

[MrDavo]

I've just been cleaning out the main horizontal oil gallery, once I'd manage to remove the end plug - IDK if mine's ben polished undersize, but the only spanner that would fit was that old Honda favourite of, er 1/4 inch Whitworth! Maybe its because oilways count as plumbing.

No glass beads or other nasties came out when I flooded brake cleaner up there, it ran out of the mains as it was supposed to do.