Topic: custom oil tank design -- feedback, please

[the architect]

I've been working on my '75 K5 since buying it a few months back.  I've decided to try and streamline things a bit.  

I'd like some feedback on this design for my oil tank.  I've gone through multiple iterations, and this seems the most promising, so far.

My calculations tell me that it will hold just over 2 liters (translates to around 2.25 quarts).  I was planning to construct it from 16ga. sheet steel, using 5/16" x 18 threaded bungs for attachment to custom fabricated brackets.  A 1-1/2" O.D. oil cap will close things off.

Questions:
  - Any general critiques on functionality of this design?
  - Suggestions on hoses / fittings?







There's a bigger image with all three views here:  http://farm4.static.flickr.com/3583/3762250071_075a4d530d_b.jpg

[HavocTurbo]

So what you're going to do is run it the width of the bike?

If it holds as much or more as the stock tank you should be fine. Some guys have even made oil tanks out of rear inner fenders and so forth.

Looks good to me!

[lrutt]

With that small amount of oil you'd have to keep an eye on it and change it frequently. There is a reason race bikes expand the oil capacity instead of shrinking it.

[nokrome]

i also have built a custom oil tank that is a little short on capacity so i will be running an oil cooler and big automotive style filter and -10 lines to try and make up for some of it......something to consider
      looks good....go for it !

[the architect]

i also have built a custom oil tank that is a little short on capacity so i will be running an oil cooler and big automotive style filter and -10 lines to try and make up for some of it......something to consider
      looks good....go for it !

Curious, where are you installing your oil cooler and filter adapter plate?  I'd like to install a cooler, too, but I can't seem to find a great, stealth location for it.

I really like your gas tank, btw.   



I can't remember where I found it, but I was thinking that the stock oil tank held 2 liters, so that was the number I was aiming for.  Perhaps I need to revise the design for some added capacity.  I really like the look of the CR oil tanks, and they kind of inspired my design.  However, since I have no plans to race the bike, I opted to not increase capacity.

Thanks for the great input, so far.  Keep it coming!   

[Gordon]

I would think that with something as important as oil volume you would want to go on better information than something you sort-of remember hearing somewhere.  Here's what Hondaman had to say on the subject a while back:

The stock CB750 tanks after K0 will hold 4.25 quarts. They will leak some out of the breather at that volume, though, until it drops to 4.1 quarts. When the engine is shut off, then drained immediately, there is approximately 0.5 quart in the engine at that moment, if the oil pump is new: typically on our aged bikes you will find closer to 1 quart down there, as the pump loses pickup efficiency.

   

[azuredesign]

I wouldn't be comfortable with so little circulating oil. Even if you could get an extra quart in an oil cooler, you're still down about 15% in volume.

[bucky katt]

needs an extra quart and a half to be safe.

[the architect]

I would think that with something as important as oil volume you would want to go on better information than something you sort-of remember hearing somewhere.  Here's what Hondaman had to say on the subject a while back:

The stock CB750 tanks after K0 will hold 4.25 quarts. They will leak some out of the breather at that volume, though, until it drops to 4.1 quarts. When the engine is shut off, then drained immediately, there is approximately 0.5 quart in the engine at that moment, if the oil pump is new: typically on our aged bikes you will find closer to 1 quart down there, as the pump loses pickup efficiency.

   

I'm not really prone to rushing to conclusion, so I wouldn't base my decision on "something I read on the internet".  Turns out my source was my factory shop manual:



Please forgive any possible misinterpretation, but this seems to be telling me that 2 liters of oil live in the oil tank, while 1.5 liters live in the engine and associated plumbing, at any given time.  Can this be correct?

I don't want to go 15% (or even 10%) down on capacity.  I'd like to break even, just taking up a better, more preferrable (to my tastes, anyway) form factor.

[Gordon]

Don't tell me Hondaman was wrong!  That would thoroughly disrupt the sohc4 space-time continuum!

[Zaipai]

I would bet on the shop manual. Personally I think its a dandy design and worth going for.

[the architect]

Don't tell me Hondaman was wrong!  That would thoroughly disrupt the sohc4 space-time continuum!

Oh, I make no mistake about it:  Hondaman has definitely secured his place as a SOHC Honda deity 

[nokrome]

Curious, where are you installing your oil cooler and filter adapter plate?  I'd like to install a cooler, too, but I can't seem to find a great, stealth location for it.

  the cooler will be located in the standard spot mounted to the frame behind the forks just below the steering neck and the adapter plate mounts in the stock oil filter location.

   i understand that if you are doing some serious racing you may want extra oil capacity but it looks like you will be well within the acceptable limits according to the manual

   in theory what difference does it make how much oil you have in the tank as long as you have enough in the engine and it is kept within the proper temp range?

[HavocTurbo]

I did some checking... visual on a lot of different bikes..

I have yet to come across a 750cc or close bike that takes more than 3.75 quarts.

I did find a 1200 that took 4200cc, but that thing was a big twin.

[myhondas]

what part of that chart did someone mis-read?  2 liter on the right side equaled 4.22 pts which = 2.1 quarts. It's hard to believe that Hondaman would post 4.25 quarts. I sure that pints is the correct volume.

[the architect]

I'll move forward with a +/- 2 liter oil tank -- thanks for the added comments!

In looking at so many other tanks, I'm thinking my proposed design may have the added benefit of keeping the tank lower on the bike, and (hopefully) transmitting less heat to the underside of the rider's seat.

[MCRider]

I'll move forward with a +/- 2 liter oil tank -- thanks for the added comments!

In looking at so many other tanks, I'm thinking my proposed design may have the added benefit of keeping the tank lower on the bike, and (hopefully) transmitting less heat to the underside of the rider's seat.

Manuals have been wrong before. I'd simply take the stock oil tank, plug the holes, fill it up to the full mark on the dipstick, pour it out and see. I'll bet its closer to 3+ quarts. With some dead air above the full mark that can be slimmed out, but it probably serves a purpose of some sort, venting or some such.

I may do that in my next shop session this weekend, just to answer the question.

[754]

When crossing deserts at 100 degrees or more, or sitting in traffic in those temps...
 sure is nice to be able to throw another Quart in..

[the architect]

When crossing deserts at 100 degrees or more, or sitting in traffic in those temps...
 sure is nice to be able to throw another Quart in..

Plenty of traffic and heat, here (Houston, TX).  Maybe I'll see about working in a little extra capacity.

[HB-1fan]

I say as long as you have the volume, go for it!
 Lower center of gravity is always a good thing. Consider bleed back/overflow if you mount a oil cooler higher than the tank! Which might give you an idea how worn your pump is, as I'm guessing it should work as a check valve to some extent.

 Was considering building cr replica tanks! Anyone out there ever seen one cut open. I heard there was some tubes routed behind the inlet and/or outlet. Maybe a baffle or two??

HB

[myhondas]

When crossing deserts at 100 degrees or more, or sitting in traffic in those temps...
 sure is nice to be able to throw another Quart in..

Plenty of traffic and heat, here (Houston, TX).  Maybe I'll see about working in a little extra capacity.

+10 on the volume  can never have too much when you are dealing with heat.

[754]

CR tanks?
 There is 20X the demand for a nice alloy CB 750 bucket, with matching alloy left sidecovers... but that is JMO..

[HB-1fan]

754,
 Do you mean a stock type oil tank in alloy? What a concept! Never thought of it. Always wanted to reproduce the vintage race stuff.

Had my eye on some large alloy heat sync(big fins) material and wondered what I could do with it. Maybe use it as side cover and weld half a tank to the back side. What ya think?

HB

[754]

Now we are talking.. any way you look at it changing that area cost money.

I think A nice alloy tank would look good and maybe cool better. I am thinking of one with a bit of a  change to it, but wont work with stock frame.

[Alan F.]

Now we are talking.. any way you look at it changing that area cost money.

I think A nice alloy tank would look good and maybe cool better. I am thinking of one with a bit of a  change to it, but wont work with stock frame.

I've been kicking the idea around too, but it'd have to be simple to make and fit stock frames easily without having to move the battery or electrics.  I've got some time on my hands this weekend, maybe I'll come up with something to post later.