Topic: How does the A model accomplish its wet sump?

[Shenanigans]

I would really really like to lose the oil tank from a K. I have searched and have not come across anything significant other than a reference that there used to be a kit to wet sump the bikes via HondaMan.



Is it really as simple as making the pan deep enough to hold enough oil and lowering the pump? I checked the Auto's sump pan and it is massive (and seemingly incompatible) with the K bikes.

What does the A' got that the K's dont!

[JLeather]

The A has an entirely different oil pump.  It's technically two pumps in one (two rotors).  It's off to the left-ish side of the engine and it pumps a whole lot more oil than a K pump, but that's mostly because it uses oil pressure to lockup the clutch packs (like a real auto trans).

As for wet-sumping a K, the kit was a spacer to lower the existing pan like an inch or so, and an extension for the pump.  I'd recommend installing a baffle of some kind as well.  The A pan has a baffle that allows oil to run into the area the pickup is in, but not out of it so under heavy braking the oil doesn't run forward and allow the enigne to run dry for a moment.

[HondaMan]

JL has it right: there were actually 2 "kits" out there in the late 1970s for the wet sump. One was a "ring" arrangement, shaped like the existing oil pan, that just dropped the pan down. It had an adapter plate that the pump bolted to, with passages for the pump to lift the oil through. This version did away with the screen, though, and I think it had some problems, as it disappeared after a couple of years.

The other version was a whole dropped pan casting with built-in pump mount and a dropped pickup channel for the screen. It was hard to install and typically leaked, but more common. I have seen these in boneyards from time to time, on grimy bikes.

Neither one allowed much oil, dropping the oil quantity down to about 2.5 quarts, I think it was. Here in Colorado, owners who wet-sumped often also installed oil coolers (at least most of them that I noticed), as it did make the oil run quite a bit hotter without the tank to help cool it down. It also caused drag on the transmission gears, losing a little torque in the process, but undoubtedly increased the gear lube action. This is where some baffling could help. Also, install a crankshaft windage tray if you go wet sump, or it will cause considerable drag on the crank. I don't think there would be a way to install a windage tray for the trans gears, though: just not enough room in there...

[Shenanigans]

Thanks, I always wondered about the A's and now I need wonder no more. It sounds to me like I will be staying away from the wet sump. Maybe I could hide it in the back of an extended gas tank.

Which brings me to another question, could the oil pump handle the longer lines of the oil tank being moved to about where the end of the stock gas tank would be?

[MCRider]

Thanks, I always wondered about the A's and now I need wonder no more. It sounds to me like I will be staying away from the wet sump. Maybe I could hide it in the back of an extended gas tank.

Which brings me to another question, could the oil pump handle the longer lines of the oil tank being moved to about where the end of the stock gas tank would be?

I'm sure it was someone here but i can't remember who so i apologize, tweren't me, thinking of a CB750 cafe tank as so. A relatively flat rectangle that would lay inbetween the frame rails replacing and doubling as the plastic inner fender. It could be 2 inches thick or more and hold a lot of oil. Then if its a kick only, a flat battery could be mounted about where the airbox was, between the frame rails, and the misc electrics in the seat bubble. Then you'd have that see thru look.

I just can't bring myself to hang the battery back there too, but if you're OK with it, one would have that open look.

[Shenanigans]

The only 750 I have seen with the oil tank completely out of the way was this. The lines run all the way to the rear cowl. I dont think that is a true functioning bike however. "Art" and all... but still cool none the less.

[NitroHunter]

Some of the way cool custom V twins pump the oil into the frame rails to use as the sump. Makes them very clean, ya gotta really look at them to find it. Wish I'd of thought of it...

[JLeather]

Didn't the JapAuto or one of the other endurance racers run an additional oil tank in the seat cowl?  Frankly, it isn't that much more work on the pump.  You might wanna run larger diameter oil lines, but I think it'd be fine.

[Don R]

There is an A engine for sale on the St. Louis /Craigs list for 100.

[HondaMan]

Some of the way cool custom V twins pump the oil into the frame rails to use as the sump. Makes them very clean, ya gotta really look at them to find it. Wish I'd of thought of it...

I think it was BSA who did this in the 1960s, and Triumph (and I think Norton) did it, too. I remember seeing Dunstal bikes with tiny oil tanks being raced, and the owners talking about how hard it was to hollow out and clean the frame pipes to pass the oil. It let them cool it without the extra weight and wind resistance of a cooler, always helpful on the track. Dirt racers on Brit Twins did it, too, to prevent lost oil lines from flying rocks in dirt track roundy-rounds.

IIRC, wasn't this shown on a movie, like "On Any Sunday", too?   

[MJL]

http://www.tanksbytigman.com/index.shtml

IIRC the rear part of the tank is an oil tank.

I have also heard of people using the swingarm as an oil tank.

[MCRider]

SNIP
http://www.tanksbytigman.com/index.shtml

IIRC the rear part of the tank is an oil tank.

I have also heard of people using the swingarm as an oil tank.

I like the elegance of the oil tank part of the gas tank, but that might get a little warm between the legs.

Buell sports bikes use the swingarm for an oil tank. Again elegant on the surface, but its unsprung weight. Though close to the pivot so minimized.

The 70s era triumphs had the oil in an enlarged backbone tube, hence the "oil in frame" tag, but it did not run in the frame at large, as some might think. And it raised the center of gravity. The 70s era Triumphs had higher seat height and COG than their pre-70 brethren, a step backwards in my mind.

Custom bikes using the traditional frame tubes as the oil tank is by far the coolest, and hardest to accomplish I'm sure. No extra hardware, (perhaps slightly larger diameter tubes) and no interference with design principles like keeping the heat away from the rider, or adding unsprung weight.

It would be hard to convert a traditional bike, like our CBs to oil in frame as the tubes weren't designed with a continuous flow in mind. Like at the steering head.

[HondaMan]

It would be hard to convert a traditional bike, like our CBs to oil in frame as the tubes weren't designed with a continuous flow in mind. Like at the steering head.

Roger that! I would be helpful, though, to the handling of the CB750, to replace the lower frame cradle with larger tubes, while also arranging them somehow to handle oil. I can visualize a nice, smaller (like 2 quart) oil tank just above the swingarm crossmember, and using 1.25" diameter frame tubes for a 1" ID volume, but the enbine mounts could be welded to the top of the lower cradle, making the frame lower...Hmmm....

[MCRider]

It would be hard to convert a traditional bike, like our CBs to oil in frame as the tubes weren't designed with a continuous flow in mind. Like at the steering head.

Roger that! I would be helpful, though, to the handling of the CB750, to replace the lower frame cradle with larger tubes, while also arranging them somehow to handle oil. I can visualize a nice, smaller (like 2 quart) oil tank just above the swingarm crossmember, and using 1.25" diameter frame tubes for a 1" ID volume, but the enbine mounts could be welded to the top of the lower cradle, making the frame lower...Hmmm....

If one were obsessed with the notion... coming off the oil filter adapter, with tubes underneath as you mention, and a built in oil cooler, piggy back some tubes here and there, large tube or flat container transverse underneath,  hmmmm. Glad its beyond my poor powers to add or detract.