Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: ace cafe racer on October 30, 2019, 10:26:25 PM
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As title its on one of the oil pipes from tank to engine
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It looks suspiciously like an on/off valve someone has fitted, presumably to stop oil draining back down into the engine.
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Agreed with above. I have seen this done before. It's a manual valve to shut off the oil supply to stop it wet sumping. They have spent more time rigging that up than it takes to fix the problem correctly. Plus, forget to turn it back on and see how long your crank and cams last. I would bet it's jammed solid anyway.
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Agree Roy ;D ;D worked with someone year's ago, had a Triton or Norton Dominator on which he did exactly that. Proud of his technical starting routine, forgot the oil line tap and siezed it on the way home :-[
It's funny that someone has sought to modify what is one of the best original specifications oil systems from that era, as above it should just be maintained correctly to work without extra equipment.
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Thanks for the input funnily enough not really taken much notice of it before until I decided to fit a new pump to prevent the wet sumping.
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Or it may have been fitted as an isolation for maintenance work. Saves draining down the tank if disconnection is required. I wish I'd fitted one to my '66 Triumph 500 when I built it.
I know the next thing to be said will be.... "but you could still leave it closed after maintenance by accident" True but then I've seen an engine changed at the track and engine oil forgotten to be filled, seized after burnout at the tree.
I have a NO OIL label that goes on my ignition switch for this reason.
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that contraption is not needed on any cb750 as all the oil that finds its way into the sump will get sucked back into the oil tank by the scavenger pump and the delivery pump will do the rest
like its already been said its not the case on any old britt bike and they all do it if the oil is not drained from the sump before starting with such a small crank case the surplus oil will be forced out through the engine cases and you will be welcomed by a huge puddle of black oil
i have a BSA a10 650 and if its not used for more than a few weeks it will wet-sump and i have to drain the sump and refill the tank but i still prefer to do this than fit one of them taps to the oil lines and it only takes a few minutes
i have heard so many stories of guys forgetting to turn the taps back on after a long lay-up and bang its too late
keep it simple guys the older we get the more we FORget :(
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My second ever bike was a BSA C15 that kept wet sumping because the non-return valve was stuck open. My Dad made a new non-return valve in his workshop and fixed it for me. That saved me a fortune in oil. ☺