AJS & Matchless Owners Club

Hello everyone, it's been a while since I've been on here life and other projects got in the way of finishing the 18s.

I've rebuilt the gearbox and now if I want gear oil on the floor I have to put it there meself.

I've had the barrel off to install a compression plate to compensate for the metal I had to take off the head because of damage.

She started easily yay, oil returning to the tank sounds nice apart form a noisy tappet.

I took her for a ride about 10 miles. She started to make hard work of everything and when I got home the primary case and crankcase were full of the oil that should have been in the tank. The good news is it did not leak a drop onto the floor.

But my question is could it be anything other than a blocked oil way or do I need to split the crankcase to get to the pump ?
I hope the vast experience on here could point me in the right direction.

Thanks in advance Harry

Hi there harry, the oil was returning after your rebuild, does it still? If it does then obviously it's not enough but at least not a total blockage. The only thing I can think of that's not a blocked oilway is an air leak on the return side (square flat plate) of the oil pump, maybe a faulty gasket, it doesn't take much of an air leak for air to be sucked in rather than to draw oil up.
Happy hunting!
Dave.

Thanks Dave,

After sulking last night my plan is to remove (if I can) the plate at the back of the oil pump. If I have my theory correct I can then turn the engine till the oil pump ports line up and squirt oil back through the pump into the crankcase. With the drain plug removed I'm hoping that will clear any blockage.

Harry

Has it been laid up, could it have wet sumped?

Duncan wrote:Has it been laid up, could it have wet sumped?

Hi Duncan, There is no doubt it wet sumped enough to also fill the chain case and contaminate the clutch to the point where I can't kick the engine over.

But I was riding it at the time

Hi

It sounds like this was your first ride post re-build, which would suggest to me the scavenge gallery has become:

Blocked, (not initially but at some point during the run), in which case you will no longer see a return.

Partially blocked with debris, in which case you may see a reduced return flow.

The air leak at the cover plate is also a possibility, in which case you may see a reduced return flow.

Also, have you checked you've assembled the oil pump plunger pin in it's correct orientation, larger diameter upwards?

Regards Mick

Mick D wrote:Hi

It sounds like this was your first ride post re-build, which would suggest to me the scavenge gallery has become:

Blocked, (not initially but at some point during the run), in which case you will no longer see a return.

Partially blocked with debris, in which case you may see a reduced return flow.

The air leak at the cover plate is also a possibility, in which case you may see a reduced return flow.

Also, have you checked you've assembled the oil pump plunger pin in it's correct orientation, larger diameter upwards?

Regards Mick

Exactly that Mick, Thanks, the pump is assembled right as I haven't touched that since the first build. I made some schoolboy errors. The first was to drain the crankcase into a dirty drain tray, so I'm unable to search for debris. Then having back fed to scavenge pump with brake cleaner then oil I know its now clear. I pushed the bike outside and it wouldn't start. Schoolboy error two the plug lead was off and once refitted the clutch decided to slip (due to the excess oil no doubt even though I had drained it off.) So it won't start.

So it is now back on the lift with the clutch lever cable tied to hold the plates open while every now and again I squirt it with brake cleaner. I'm working this week so I'll leave it till next week

Re :- wet sumping :- apparently if you leave the piston at tdc on compression stroke this does not happen.

without an oil filter there could be sludge stuck in the system, clean the gauze strainer. is the strainer on the correct oil line.

have you been able to confirm oil is flowing to the rockers? take inspection cover off with motor running. it could take a while.. if the motor starts to get too hot shut it down. the scavenge side of the pump could be to blame.

oil pump animation.

Allen_F wrote:Re :- wet sumping :- apparently if you leave the piston at tdc on compression stroke this does not happen.

without an oil filter there could be sludge stuck in the system, clean the gauze strainer. is the strainer on the correct oil line.

have you been able to confirm oil is flowing to the rockers? take inspection cover off with motor running. it could take a while.. if the motor starts to get too hot shut it down. the scavenge side of the pump could be to blame.

Tricky trying to keep the piston at tdc when the engine is running

Cheers Harry