Please can i ask for some advise with a worry i have come across whilst recomissioning my long laid up Commando 750 in a slimline frame. During general tinkering and working i found the chaincase to be full of oil (its running a belt) i figured that the crankcase seal may have blown so i replaced it. Also, its had a recent barrels and head off for a rebore and head service by a local engineering company.All back together and the bike started reasonably easily, however i cant see any oil returning to the tank. Its a 'unity equipe' oil tank and not the easiest to view oil return. However in the past i can't rememember oil return been difficult to see. (The oil lines aren't reversed). i have run the engine for a few minutes at around 2000 rpm, but i can see nothing other than a few odd bubbles. I haven't had a chance to do any tinkering for a coupe of weeks until yesterday. The oil level has dropped, i drained the sump to find circa a pint of oil, may be more. (Not that uncommon as i remember in the past). My question is where do i start looking, is there any sensible checks i should be making or do i suspect the oil pump is at fault Your help and advice would be greatly appreciated . Kind regards Ant
If you only took head and…
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Thanks Robert for your tho…
Thanks Robert for your thoughts. i am reasonably sure that nothing dropped into crank case whilst rebuilding as it was carefully packed out, but not beyond consideration. Your air locked idea was a thought that had crossed my mind and i definitely want to check later today if get a chance that the oil level could be above the return. Thanks again, will keep you posted.
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Antony If you're sure tha…
Antony
If you're sure that the oil lines aren't reversed - btw the parts manual is incorrect, see the diagram in the workshop manual (Fig C29) which is correct - then I suggest checking the condition of the 'Feed Bush Sealing Washer' (aka Oil Pump Seal). Part No. 28 in the diagram here:
Needs removal of the timing cover and I'd recommend replacing both oil seals (28 & 21) and the gasket whilst here - assuming not already done following lay-up.
Hope this helps.
Andy
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Many thanks Andy, as per y…
Many thanks Andy, as per your suggestion i did check the oil lines. The infeed and return do have crimped fittings so you cant actually dismantle and mix up. The do look like fig C29. (the inside is the return).
Thanks for the help with the diagram and seal references, I am preparing to take a look inside the timing cover side and going to take the oil tank off completely as i am really struggling to see where the return pipe terminates (as per robert suggestion about overfilling).
Interestingly on removal of the point cover, there is oil at the base of boyer ignition back plate.
Kind regards Ant
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Check the pump suction oil…
Check the pump suction oilway from the sump to the pump, it maybe blocked at the change of direction. This can be done without removing the cases from the frame, just the timing cover and oil pump, remove the sump strainer and feed oil into the oil pump suction port on the RH crankcase - it should quickly drip from the hole where the oil is sucked from the strainer. Some check this with wire from both directions, but seeing as there is a change of direction, they mistake the wire stopping as the end on the hole when they hit a solid build up of debris.
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If you only took head and barrels off the only thing you could have done is drop rubbish in and blocked the pick up. But I suspect the oil draining down has left you with an air lock in the pipes. Its also possible if you drained the sump that a drained and tilted motor will take some time to sump enough oil to get the return working. Have you overfilled the tank above the return?.