Custom oil tank


New Member
Hey guys, I build a custum oil tank for my Cb750 and I have a few questions.

This tank mount under the seat so I'm gonna have to replace the original hoses. Do I need specials hoses or just something that will resist the heat ? Does the length of the hoses matter ? Will I have to compensate with a smaller diameter hose so the pressure is the same as with the shorter hoses ?

Also, on the original hoses, the fittings seems a bit overkill. Can I just use some strong pipe clamps ?



Over 10,000 Posts
Any hoses that are made for oil/fuel will work fine. If you make them longer than you just need to compensate for volume.


Over 1,000 Posts
if that tank sits flat i dont think it will work correctly
the original design is tall for a very good reason and internal design is very specific
nice work tho


New Member
Yeah I was worried about that, but my dad and I worked on the internal so the oil stays in the middle of the tank during acceleration and braking.

We also added a check valve to the oil cap.


I make things.
I'm not sure about the check valve, do you have an overflow line running to the crankcase? If not, you really should, and if you do, then you won't need a check valve. If you have a check valve and no line running to the crankcase, here's what'll happen.
1: the check valve is set to allow air in but not out - as the oil heats up in a closed space the pressure will build, forcing oil out of the tank, you may find the return line isn't feeding the tank but the oil is just building up in the sump
2: the check valve is set to allow air out but not in - as the oil circulates it foams, gradually the foam will wind up being pumped out of the tank, bringing some air with it, without air being let back in, the pressure will drop, foaming more oil and increasing the effect until the entire tank is filled with foamed oil, and thats what will be lubricating the engine


New Member
Hmm... Makes sense. What if I remove the check valve and just put a tube that goes to a little vented reservoir ? I'm not to worried about the crankcase vent, I'll just put a hose that goes in the atmosphere.


Over 1,000 Posts
i think you run into the real risk of feeding bubbly oil to the pump with such a shallow flat design
bubbly oil is compress-able which means you loose oil pressure which leads to crank failure
what was the reasoning in turning the tank into a flat shallow deal ?


Over 1,000 Posts
d4rkne33 said:
Looks man, looks !

How would the oil get bubbly with a flat design ?
i thought so, looks over function :'(
it may be somewhat bubbly on its return a deep tank lets da bubbles settle out
you never see flat shallow oil tanks used on dry sump systems it is the worst way to do it ::)
google dry sump oil tank and look what you find
it a terrible design don't say you weren't warned
the good news is you have the skills to build a really nice looking proper functioning tank


New Member
I get what you're saying. Anyone care to join in? I'd like to get a second opinion... I'm getting a little sad here...

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