Topic: Question for Hondaman re: Oil Capacity

[Bob Wessner]

Hmm, I was half hoping it was some later model tank with lesser capacity. Since that isn't the case.. 

[upperlake04]

congratulations  Bob - not often someone stumps the entire group   I have no ideas either - pic of a 78 750F3 tank

[HondaMan]

Upperlake: where did you get my High School portrait? I looked just like that...

Bob: here's some pix of a K4 dipstick and tank, same as my K2. It appears to be 3.625" from bottom-of-cap to top-of-oil mark on the dipstick. The tank is more rounded than yours, which makes yours the K0 tank. Does this give any clues?

[Bob Wessner]

Does this give any clues?

Mark,

No, not really. I would assume the older tank might have a bit greater capacity, but not that much and the dip sticks appear identical.
My decimal conversion skills suck, but my "full" mark is 3-9/16 in. from the base of the cork casket. Is that the same as 3.625 in? If so, maybe the tank capacities are identical, just slightly different shapes.

[HondaMan]

Hmm...too many years in a machine shop, I guess... the .625" is 5/8". Sorry.

When I last added the recommended 3.7 quarts. it just touched the full mark. When I pour in the rest of the 4 quarts, it's only about 1/4" above the full mark, and has no side effects that I've ever seen.

Now, the mystery goes on. I have another K4 tank. Maybe I'll try to measure its odd dimensions and we could compare that? I just can't ever remember using less than 3.7 quarts in any of the 750s I worked on. Even Jim Chamberlain's K0, the 2nd one sold in Peoria, IL in 1969, held the 4 quarts with ease. He and I worked together and fell for the 750 together... 

[Bob Wessner]

Hmm...too many years in a machine shop, I guess... the .625" is 5/8". Sorry.

When I last added the recommended 3.7 quarts. it just touched the full mark. When I pour in the rest of the 4 quarts, it's only about 1/4" above the full mark, and has no side effects that I've ever seen.

Now, the mystery goes on. I have another K4 tank. Maybe I'll try to measure its odd dimensions and we could compare that? I just can't ever remember using less than 3.7 quarts in any of the 750s I worked on. Even Jim Chamberlain's K0, the 2nd one sold in Peoria, IL in 1969, held the 4 quarts with ease. He and I worked together and fell for the 750 together... 

So far, the benign tumor occupying space has the lead. 

Just for my own sanity, here is my oil change routine;

1) Center stand the bike after a ride while the oil is hot/thinnest
2) Remove plug from oil tank and drain, when no more comes out, put the plug back in.
3) Remove oil pan drain plug and oil filter housing and let all the oil that will drain, drain.
4) Kick over the engine a couple times and let a little more drain (I probably repeat this 3 or 4 times over 15-20 minutes, can't believe a Honda service tech would wait this long).
5) Reinsert pan plug, install new filter and "O" rings and remount the filter housing.
6) Pour 2.5 qts into the oil tank and turn the engine over enough for the oil level to drop, then add the remaining .5 qt.
7) Start the engine and let it run a minute or two checking to make sure oil is circulating through the tank.

When I shut it off after this routine, the oil level is literally right up to the top mark on the dip stick. It uses no oil, so this is the same level I find after a ride until the next oil change is due. Anything amiss here? 

[HondaMan]

The only thing you note that's different from my usual routine is the clearing of the pump by kickstarter. I think that whole volume amounts to around 2 ounces of oil, nothing significant there.

You're not using imperial quarts, are you? It holds 3 of those... 

[Bob Wessner]

You're not using imperial quarts, are you? It holds 3 of those... 

No, wish it were that simple. 

There are only two things I can think of that might have any bearing on this at all. Would it make a difference if I were to leave the tank plug out while kicking it over during the draining process? Isn't some oil being pumped, or trying to be pumped back up to the tank. Granted, it may be a very small amount. Also, I don't think the center stand is correct for my bike, I think it sits a little too high. Could this affect how much oil can be gotten out? It did not have a center stand when I got it, I added it but never gave it much thought, figured a 750 center stand is a 750 center stand.

[cbjunkie]

what was the question again...?

 

[HondaMan]

There are only two things I can think of that might have any bearing on this at all. Would it make a difference if I were to leave the tank plug out while kicking it over during the draining process? Isn't some oil being pumped, or trying to be pumped back up to the tank. Granted, it may be a very small amount. Also, I don't think the center stand is correct for my bike, I think it sits a little too high. Could this affect how much oil can be gotten out? It did not have a center stand when I got it, I added it but never gave it much thought, figured a 750 center stand is a 750 center stand.

Even if you were to drain that remaining oil, it would not be 1/2 quart. The pump itself holds less than an ounce, the hose about 1-2 ounces, which won't make it to the oil tank, anyway, because it's uphill.

The K0 centerstand issue was manifestly different from the later models, but not because of parts. I remember hearing a lot about how hard the K0/K1 (even my own) centerstands were hard to mount. I've never looked into WHY they got easier to lift, because the stand never changed, to my knowledge. I suspect the mounting point rose a little under the bike (the pivot points) in the K2, because I distinctly remember how much easier my K2 was to lift than my K1. I also remember (briefly) aftermarket springs that were not so strong (for the centerstand), and a real $#@%! to install.

If you think there might be some oil hiding (although I doubt it could be much) toward the front, you could try draining it by holding the bike upright from the sidestand while draining the engine. There are also 2 "plug caps" on either side of the engine, but I think they are unreachable when it's in the frame: I'll go look at mine. These caps appeared in late K0 (non-sandcast models), and I've never understood their specific function, because the oil pan drain is lower than they are. Each cap holds about an ounce of oil: they look like smaller versions of the valve cover caps, and I think the socket is 14mm. And, they are fragile, not meant for frequent removal.

I'll have to measure the K4 tank, just to compare... 

[Bob Wessner]

Thanks Mark. For giggles, I'll do an oil change in the near future and not replace the tank plug right away and I can level the bike by shimming the front wheel while on the center stand. I can tell you mine is a b_tch to get up on the stand without my "cheater board." I'm no Arnold S., but I'm 6'4" and 230 and can manage to get a 750 engine out of the back of my car alone (though doing so often is not recommened or enjoyed  .) This time I will precisely measure the total amount of oil retrieved. Hell, I'll even take a picture of said retrieved oil. 

[USN20]

I don't think the center stand is correct for my bike, I think it sits a little too high. Could this affect how much oil can be gotten out? It did not have a center stand when I got it, I added it but never gave it much thought, figured a 750 center stand is a 750 center stand.

You may have a different center stand ...

The good news is that my CB750 Honda parts book (dated 1974) shows that all the center stands up through and including 1974 share the same part number: 50500-300-020B (I don't know about '75 and up)

[CB750F2]

Bob, it is almost as if you are using imperial measurements. 3 qts imperial is very close to 3.7 qts US. If this is not the case I suggest that you blank off the tank outlet and fill the tank to the upper level of the dip stick with a measured volume of oil and do this with other models for comparision. My Honda manual shows the same volume for models K0 to K4. Tank shape is not necessarily an indicator of volume. Pat

[HondaMan]

Thanks Mark. For giggles, I'll do an oil change in the near future and not replace the tank plug right away and I can level the bike by shimming the front wheel while on the center stand. I can tell you mine is a b_tch to get up on the stand without my "cheater board." I'm no Arnold S., but I'm 6'4" and 230 and can manage to get a 750 engine out of the back of my car alone (though doing so often is not recommened or enjoyed  .) This time I will precisely measure the total amount of oil retrieved. Hell, I'll even take a picture of said retrieved oil. 

Can you take a picture of the centerstand mount? It's visible from the left side, just above the pipes. Mine is angled about 40 degrees off of the frame, it does not go straight down. I seem to remember that the toe tab for the centerstand moved, and the result was that the K0/K1 pipes, when used on K2-later, would cause the centerstand toe tab to hit the pipes, missing the rubber bumper. If yours is directly below the frame, this would add about 3/4" to the height of lift. Heck, the bike's only 540 lbs, anyone can lift that...

As long as we're playing with things...   

[Bob Wessner]

Mark,

Here are some pics. The center stand (left and right). I've known it was not the correct center stand as the toe kick hits just below my left passenger peg and does not contact the bumper on the muffler. However, I never really gave the height much thought, much less the affect it might have on draining all the oil, though I can see how a change in angle might, but to what extent, who knows. By the way, when extended, the rear tire is approx. 1.5" off the garage floor.

However, the plot thickens. I haven't done another oil change yet, but decided to mark off qts on an empty gallon plastic milk jug to I could measure how much comes out when I do the change. As I was doing this, I was using my wife's kooking measuring cup. Thought, hmm, can't get four qts in this gallon jug. My wife walked in as I was doing this and I pointed it out to her there was 1/3 cup left over that would not fit. She said. "Is that a liquid measure cup, or a dry measure cup?" I said, "Hell, I don't know it's your cup."  Anyway, did it again with a different milk jug, same results. Either I am using the wrong kind of measure, or the dairy industry has been screwing us all out of 1/3 cup of milk in every gallon. 

Anyway, after marking the jug, I remembered I hadn't disposed of the last change's oil, so that is the third picture, a comparison of what I got out vs. a jug marked in 1 qt. increments. If I'm using the correct measure to mark the jug, I'm getting out what appears to be about 2.5 qts. but can put in 3 qts.  There might be some small amount held in the filter itself, but can't imagine it's much.

See what you get to spend time on when you're retired. 

[CB750F2]

Bob, have you read my reply? Pat

[upperlake04]

Your wife on to something - just checked a conversion table http://www.onlineconversion.com/volume.htm
1 US quart liquid=.86 US quart dry

[Bob Wessner]

Bob, have you read my reply? Pat

Yes, I did, not Emperial qts.

[Bob Wessner]

Your wife on to something - just checked a conversion table http://www.onlineconversion.com/volume.htm
1 US quart liquid=.86 US quart dry

All her measuring cups work out the same way, and they are HER cups  so I don't know what to say. None are marked as either liquid or dry measures.

[Bob Wessner]

Your wife on to something - just checked a conversion table http://www.onlineconversion.com/volume.htm
1 US quart liquid=.86 US quart dry

I' making the assumption (falsely perhaps) that liquid measure cups have the pouring spout and dry measure cups have a straight/flat rim all around for leveling. I know we have at least one chef here, maybe he could straighten me out on this earthshaking assumption. 

[Bob Wessner]

OK, here's the final verdict, finally got around to a ride followed by an oil change. Pretty much three qts out after three qts in. It's just shy of the mark, could be my marking the container, the oil in the filter or minimal dribbles when I drain the oil.. need a better shaped container. After draining everything, and leaving all plugs and filter housing out, cranked over the engine 3-4 times over a period of 15-20 minutes. Nothing more came out on the last crank-over. I also shimmed the front a bid in case the current center stand, which is incorrect for a K0, might be sitting at and angle of some sort. It did not seem to matter. I did satisfy myself that after draining the oil tank, nothing more will come out during cranking. It was mid-eighties today and the engine was good an hot and oil thin after about a 50 mile ride. So, unless Mark (Hondaman), someone, anyone can figure out what the diff. is, I have a 3 qt. 750 and no explanation of why that is. 

[cbjunkie]

that's what mine takes...

dude, bob, man this thread is totally faq-worthy

[HondaMan]

Finally got to check the K2/K4 tanks. The "depth" of the tank is 4-5/8" where it goes between the triangle of frame rails, toward the battery.  The very curvy "face" of the tank is only an inch or less depth: this is how the K1-later ones felt "narrower" because they did not bump into your thighs while standing still.

What I'm wondering is: how "deep" into the frame does your K0 tank go?

And, this is a little off-the-wall, but I saw 2 unique "750" bikes that were not 750s, back in 1970-71. They had a longer stroke and narrower bore than the stock 63x61mm. They were real "mystery bikes", also screaming performers, and the little "label" cast on the front of the engine on those two bikes did not have "736cc" cast onto them. They were blank. Their gas tanks held only 3.8 gallons (I think it was, but I know less than 4.0 gallons) because the coils were different (bigger, with replaceable wires that screwed on with caps) and the tanks were indented (at the factory) to clear them. Now, I wonder about their oil capacity, but never knew at the time. They had bigger-than-CB750 intake valves, too.

Does your K0 show "736cc" on the front of the engine?    

[Jonesy]

I think it's safe to say Bob has finished his basement remodeling project, because now he obviously has waaaayyy too much time on his hands! 

[Bob Wessner]

Attached are a couple of more pictures. One gives some idea as to how far the oil tank intrudes into the frame. Yes, I have the 736cc cast into the engine between #1 and #2. While out there, grabbed some shots of anything that could otherwise impact oil capacity (e.g., oil pan, filter housing, etc.). Nothing seems out of the ordinary. One thing I would note, not that it would affect anything..I don't think, is that I'm assuming the engine suffered the infamous "chain through the case" scenario as the VIN plate on the engine has no number stamped and the depth of the border around the area seems deeper than on an original case. I have a spare engine with a VIN # quite close to mine in the garage.

Edit: Actually, the basement is not yet finished  but it is in a phase where there are, or I feel I can take some breaks... painting is boring. 

Hmm, don't know why the pics didn't attach the first time..