Hi guys
Unfortunately my reply to Cranky's post with the photos never reached the internet!
Apologies for my poor description of the oil system.
I meant that the outlet from the oil cooler goes directly to the cams then drains through the heads, barrels, casing in the normal way. Unlike the later 750's that have a return line to the oil pump area.
I will do a hot compression check for blow by. Hopefully that will be ok, as the cold leakdown check was good after I relapped the valves. But good to confirm.
And thanks for the photos. Very useful knowledge!
Cheers
Rob

Hi folks,

I ran the engine for about 15 minutes and the oil pressure reduced to around 6 bar (87 psi) at 3000 rpm and 5 bar (73 psi) at 2000 rpm. So hopefully there is no major blockage in the delivery system.
The oil was still foamed during the running but did seem to clear relatively quickly after the engine stopped.

The hot compression test showed 11 bar (160 psi) from the horizontal cylinder and 11.25 (163 psi) bar from the vertical cylinder. So things look pretty healthy in that respect.
(I have ~ 1.3mm squish with the Pistal HC pistons and plenty of valve clearance with the ST2 cams)

If the oil looks OK and I don't have the same magnetic sludge on the sump plug when I dump this fill, I'll assume all is OK and progress without stripping the engine.

Next will be to finish the wiring, then fit the tank and seat and run it through the gears down the road.
That should be fun. I'll let you know how it goes

Thanks for all the input.

Cheers
Rob

My little cure for helping with condensation is remove the oil filler cap after the engine has run, it seems to have helped.

Paul

Hello guys,
Apologies for bringing this up again. But I've been busy with other stuff and came back to thinking about this.
(I expect this is common to everyone )

I did find the attached photos of the 650 crankcases, after machining to accept the 750 barrels, which show the oil drain channels.
I've realized that in fitting the larger barrels I'll have lost about 3mm diametrically of the drain slots.

My question is, do you think the reduction in drain slot area could be enough to affect draining to the extent that the oil pump to loses suction and causes the foaming by drawing in air as well oil?

To me, the two vertical cylinder slots look like they ought to be adequate. But the single horizontal slot appears to be quite restricted. Or was the casting at the horizontal cylinder deliberately left partially unmachined to provide some form of guide for the oil flow?

Any opinions on this would be gratefully received!
Many thanks
Regards
Rob

Apologies, I attached the wrong photo of the vertical cylinder opening.
Here is the right one.

I have to say that the drain does now look very small. That could mean more oil now trapped and frothing in that rocker cavity. The H head is the "easy" one to pull and redo something. I'll bet you can figure out a clever way to block the inside of that spigot and then file out, or grind out, that flashing still there. It isn't that thick, and it is only aluminium - did i spell that right?. Just an afternoon of entertainment for you. Cheers, MikeV

Thanks for the thoughts Mike.

I hadn't considered excess oil frothing in head as being a possible cause.

I might try adding more oil when the bike is running to test the loss of pump suction theory.
But will need to be careful not to overdo it!

Either way, I think addressing the restricted drain will be necessary.

All the best
Cheers
Rob