Hello Jampoters,
I have a 1954 G80S and the return oil to the tank seems a little low, maybe a cup a minute at idle, how much oil should be expected?
Denny
Re: G80S Return oil flow expected?
Posted: Wed Mar 04, 2020 8:55 pm
by SPRIDDLER
Drongo wrote:Hello Jampoters,
I have a 1954 G80S and the return oil to the tank seems a little low, maybe a cup a minute at idle, how much oil should be expected?
Denny
Welcome to the Forums, Denny!
You'll only get intermittent spurts/bubbles/flow at tickover. It's an oscillating plunger with one pumping stroke for every 4 revolutions of the engine, not a rotary vane or gear type pump.
Oil circ system.JPG
Oil pump scroll and plunger.JPG
Here's an animation:
You can find original Owner and Tech manuals and diagrams for your bike here under 'Books'...……….
I've never discovered any quantitative value for the return flow but I wouldn't worry if I was seeing a cup a minute at idle.
Regards Mick
Re: G80S Return oil flow expected?
Posted: Thu Mar 05, 2020 10:11 am
by Pharisee
Mick D wrote:
Drongo wrote:a cup a minute at idle
Hi
I've never discovered any quantitative value for the return flow but I wouldn't worry if I was seeing a cup a minute at idle.
Regards Mick
Once the engine has run long enough to clear any residual oil in the crankcase, the return pump flow will be the same as the delivery pump flow.
Assuming the delivery pump is 100% efficient... highly unlikely... it will pump approximately 50cc of oil per minute at 1000 rpm into the engine. That's equivalent to about 10 teaspoons. Quite a lot less than a cupful
(Feed pump diameter 1/2", stroke 1/8", 1 cycle every 8 revolutions of the crankshaft with the later 2 start worm gear)
John
Re: G80S Return oil flow expected?
Posted: Fri Mar 06, 2020 12:54 am
by Allen_F
another thought.
Re: G80S Return oil flow expected?
Posted: Tue Aug 24, 2021 9:01 pm
by Shelby-Right
Great reading thanks , could someone tell me the locating plunger and cap /bolt ? That locates into the swash groove........, My bike came with a Fibre washer on that bolt which is wrong according to YouTube dick Casey, I have just loosened it 1 turn and then snipped the washer off , question has the plunger got a spring , would this bolt thread be sealed with 567 pipe sealant ? , I thought I may remove front oil pump cap to confirm movement , and rotation. Cheers .
Re: G80S Return oil flow expected?
Posted: Wed Aug 25, 2021 9:18 am
by clive
Th plunger has no spring. It rotates and the pumping action is governed by a a guide pin and a groove in the pump that is angled. There is a gasket between the pump plates and crankcase which should prevent any leaks. The bolt thread is blind into the crankcase, I have never found any loctite or sealant is necessary on the threads but do use something either side of the gasket, not a slicing type though and not much of it.
