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SOHC.co.uk Forums => CB750 => Topic started by: Arch stanton on March 19, 2019, 07:15:02 PM

Title: Priming oil pump?
Post by: Arch stanton on March 19, 2019, 07:15:02 PM
I have removed the spark plugs.
Put 3.5 ltr of oil in the oil tank.
Now how long should it take to notice the oil level dropping,
Using the Kick-start to turn the engine?
Your input would be as ever appreciated.
Sean.
Title: Re: Priming oil pump?
Post by: MrDavo on March 19, 2019, 07:49:22 PM
When you’re just changing the oil it’s never a problem, as the pump stays primed.

However, after my CB750 engine rebuild I had a nightmare getting oil pumping around the engine and up into the gallery with the hex plug at the end. I tried filling that with oil, and had built the oil pump immersed in oil, but it was not circulating, and I was very fearful of killing my engine - someone on the board had bought a freshly rebuilt bike with a ruined engine because it had been started without oil circulating. The previous owner had given up in despair after that, he wasn’t doing it again.

The solution, given me on this board as to remove the oil pump again, and pack it with Vaseline. That worked a treat, much to my relief. The Vaseline then dissolves into the oil without a problem.

I think Trigger may have some experience in this field.
Title: Re: Priming oil pump?
Post by: royhall on March 19, 2019, 07:54:24 PM
Ditto the above Vaseline trick, it works a treat. Trig giving away his trade secrets.
Title: Re: Priming oil pump?
Post by: Seamus on March 19, 2019, 08:14:43 PM
Old story that if you put the bike on the side stand as it helps the pump dispell the air lock. Worth a go.
Title: Re: Priming oil pump?
Post by: Arch stanton on March 19, 2019, 09:47:11 PM
It's OK Chaps.
I got it going & the oil is pumping around nicely.
Thank you for your replies.
Fill the pump with Vaseline eh. Well who'd have thought.
Anyway. That's the first time in 30yrs I have heard the bark of a Marving pipe. Nice tune.
Regards.
Sean.
Title: Re: Priming oil pump?
Post by: philward on March 19, 2019, 09:48:11 PM
Ditto with the Vaseline method - took forever when I built K2 but when built CR Rep I used vaseline method and it took no time at all
Title: Re: Priming oil pump?
Post by: Rob62 on March 19, 2019, 09:50:40 PM
Wow! Vaseline...is that a tried and tested method? Sounds a bit dangerous to me...wouldn’t want vaseline blocking up my oil galleries  :o
Title: Re: Priming oil pump?
Post by: Arch stanton on March 19, 2019, 09:54:07 PM
Just can't help wondering who thought of it in the first place. Clever. But still off the wall.
Title: Re: Priming oil pump?
Post by: Nurse Julie on March 19, 2019, 09:58:39 PM
Trigger has been using Vaseline for the past 30 years to prime CB750/4 oil pumps. Works every time, no risk to oil galleries as the vaseline just dissolves.
Title: Re: Priming oil pump?
Post by: paul G on March 20, 2019, 08:25:12 AM
Trigger has been using Vaseline for the past 30 years to prime CB750/4 oil pumps. Works every time, no risk to oil galleries as the vaseline just dissolves.
I'll second that worked for me.
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