Lack of oil to piston 1931 Model 9

jfrith · May 11, 2021, 08:50:29 PM

I have managed to source one. Thanks. All I need to do now is pay for it

singleminded · May 11, 2021, 07:39:47 PM

What size is your piston, standard or oversize..it looks like Sean Kelly at Sunbeamland is now out of stock of all the pistons he had made..i was lucky to get one off him for my 90.

jfrith · May 11, 2021, 08:10:27 AM

Great thank you
I have just found out that it has the wrong piston fitted, so I doubt that has helped matters, has a bottom ring below gudgeon pin which isn't like any Model 9 piston I have seen, (Not that I have seen many) Out of curiosity I am trying to find out what it is supposed to fit, Hepolite 812165

singleminded · May 10, 2021, 10:27:20 PM

Morris straight 40..i can't be bothered changing between 30 for the winter and 50 for the Summer..
I use the same oil in my vincent Comet and that gets it's neck wrung.

jfrith · May 09, 2021, 09:14:37 PM

Ok Thank you, I'll try and clean piston up or source another one and start putting back together. What engine oil do you use?

singleminded · May 09, 2021, 04:56:02 PM

I run my 9A on no2 all the time and have had no problems..You have to assume that if the oil returns OK that you have enough supply, assuming it's not just clearing any excess oil that sumped. These engines really don't need a massive amount of oil going through them to work properly. John

jfrith · May 09, 2021, 10:44:50 AM

Hi ignition set correctly and fuel mixture ok. I have excellent oil flow through return. I am wondering if it happened as my oil tap was set to 2 and not 3 or were the oil pipes pulling air in before I checked everything. Can I assume that if I have a good return flow everything is working as it should or do I need to investigate further?
Also I have noticed that the top of the inlet valve is practically flush with the valve retainer, it works but looks as though it is too short. I have tried to send a picture but won't let me as too large. Thanks John

singleminded · May 09, 2021, 06:19:23 AM

Have you checked that the ignition is not too retarded..you did advance it after starting?..Forgive the daft question but i don't know how much experience you have on old bikes....john

jfrith · May 07, 2021, 09:58:57 PM

Had partial seizure on piston. Cylinder bore looks serviceable after honing. Not sure if piston is salvageable. I have checked all oil pipes and gauze filters, oil pump no debris found and have an excellent oil return. Big end appears to be ok. There is approx 2mm end float in crank. Is there anything else I need to check to see what caused this problem. Thanks John