Oil cooler on an '80 750?

[reddirtrider]

Do you think that an oil cooler is going to reduce the temperatures you see between cooling fins? What's your oil temperature?

As for adding a cooler, to do it right you're going to need to understand exactly the path of your lubrication system as it exists now. Tapping into the plug on your oil filter cover is extracting oil on its initial path to the engine for lubrication. You cannot dump this back into the sump using a cooler. IMHO, it would create a low pressure path and the engine will suffer from a lack of lubrication.

The correct location of a cooler is shown in Billy's diagram. It's in line with the filter/pump and prior to being sent to the general lubrication system. If you add a cooler, there needs to be some restriction on the internal route that this oil normally flows, else it will not choose to flow through your cooler. You also need an injection point after the oil passes through the cooler on the other side of the restriction.

Unfortunately, I would guess there are more wrong ways of doing this than right.

[makenzie71]

While not ideal, as I've admitted, it's still going to be close to actual head temps. I did, however, discover that my temp sensor fits in the sensor port on the filter cover so I installed it there...not sure if it's working as of yet as I let it idle for about 5 minutes and still got no reading. I don't know what the min reading is for my Vapor.

Please understand first that I understand how a cooler system should work and where it should get oil from and where it should return it to. That's not in question here. It's a simple thing to do when the bike comes from the factory either setup for a cooler it's self or is based heavily on other models with coolers. This bike is neither of those. No cooler ports.

Also please understand that I'm not talking about running a 1" line off the cover into a 1-gallon cooler. I'm looking at 1/4"...actually, 1/4" is big in my opinion and may go smaller...because I understand that there needs to be a restriction in the flow to prevent it from being the universal "path of least resistance". I'm also trying to find ways to dump the oil that put it back into a proper area of flow.

[reddirtrider]

Ok, all good.

The restricion you want, however, isn't in the feed to the cooler, but in the path the cooler is circumventing. That will insure that oil actually flows to the cooler.

[chef1366]

Can you tap the oil from under the ignition cover? You'll have to make a return port. On dragbikes I've seen returns on the crankcase under the carbs and on the clutch cover.

[makenzie71]

Returning to the clutch cover is what I figure is easiest...returning to the head somewhere would be ideal but I don't know how to make that work properly.

Is there supposed to be a port under the ignition cover or do you mean drill and tap the case? I'll have to look up the oil flow again to know if that would be a pressure area.

[Nessism]

On the 8V engines the oil pickup point is behind the cylinder where the oil pressure sensor is. These systems send 100% of the oil to the cooler and then return it back into the engine at the same location so it can go where it needs to - the bigger the lines the better. I don't know how the 2nd generation oil system works but your idea of only using a small amount of oil through the cooler may not be valid.

[chef1366]

On the 8V engines the oil pickup point is behind the cylinder where the oil pressure sensor is. These systems send 100% of the oil to the cooler and then return it back into the engine at the same location so it can go where it needs to - the bigger the lines the better. I don't know how the 2nd generation oil system works but your idea of only using a small amount of oil through the cooler may not be valid.

His sensor is on the filter cover. He does not have this option.

[chef1366]

Returning to the clutch cover is what I figure is easiest...returning to the head somewhere would be ideal but I don't know how to make that work properly.

Is there supposed to be a port under the ignition cover or do you mean drill and tap the case? I'll have to look up the oil flow again to know if that would be a pressure area.

There is a bolt under the ignition cover. This is a direct line to oil flow. Find out how to tap this. Same theory as plumbing an oil pressure guage.

[makenzie71]

gotcha chef...there is a source there. So...how do I plumb that to a cooler without killing too much pressure from the rest of the system? I'm not worried about dumping...I can tap the clutch cover, tap the top of the crankcase, or build a fitting to run it through the filler cap hole. As people here have stated, I'm just concerned about creating a permanent path of least resistance which has the system pushing all the oil through the cooler just because that's convenient and easy while the head gets sacrificed. I think a lot of the concern is cured through using small lines.

Opinions?

[TheCafeKid]

gotcha chef...there is a source there. So...how do I plumb that to a cooler without killing too much pressure from the rest of the system? I'm not worried about dumping...I can tap the clutch cover, tap the top of the crankcase, or build a fitting to run it through the filler cap hole. As people here have stated, I'm just concerned about creating a permanent path of least resistance which has the system pushing all the oil through the cooler just because that's convenient and easy while the head gets sacrificed. I think a lot of the concern is cured through using small lines.

Opinions?

I thought that id read somewhere that some guys used the 1100/1150 oil filter covers that had tapped holes for lines on the 750s...Maybe im mis-remembering.

One of the problems ive noticed in doing anything on the 2nd gen 750 motors is that the gallery bolt is at the BOTTOM of the cases. Not UNDER but on the side at the bottom...you know what i mean damnit.

Anyway, ive often wondered if this has anything to do with the oil flow problems on that particular motor. They're somewhat imfamous for losing cams, conrod bearings, crank bearings etc to starvation. My theory, and its just that, is a poor flow mapping design from inception. At any rate, YOU"RE question is one I will ponder. With the 8v motors and the low pressure 16v motors (1100) its not so important how fast the oil is pushed, just so long as there's enough volume to keep it flowing, and to keep the pump from cavitating. On the 16v 750 motor, its a low volume, high pressure design.... so is volume even more important?

[makenzie71]

The 1100/1150 cover thing on works on bikes that are plumbed for it. Mine doesn't have feeds behind the cover like the 1100's do.

I always consider volume important due to temperature. It's not so important due to need of lubrication...look at things like wheel bearings. They see a lot of use without much in the way of lubrication. Engines produce a lot more heat, though, so the same doesn't quite apply. If you don't have enough oil moving over the moving parts, they'll heat up and begin to cook what is there which causes all kinds of other problems. I base my ideas of this on my experience with turbochargers. High oil pressure motors have issues with custom turbo setups because if you plumb a line to them that provides no restriction it can pop the shaft seals out, but if you plumb in too much restriction the thing cooks itself.

Ultimately there will be an 8v 750 motor in this bike...with the fancy schmansy 850cc setup. In the mean time, though, it'd be nice the have a proper cooler for this one.

[makenzie71]

Kinda ****es me off...I installed my temp sensor in the port on the oil filter cover and ran bike but temp never registered. I had to extend the wires...I may have botched it but I have resistance at the contacts on the connector. Oh well...I guess I'll wait and see what happens.

[TheCafeKid]

Kinda ****es me off...I installed my temp sensor in the port on the oil filter cover and ran bike but temp never registered. I had to extend the wires...I may have botched it but I have resistance at the contacts on the connector. Oh well...I guess I'll wait and see what happens.

Gonna be a trick getting that 8v motor in that frame. They are wholey different. Id say it would be easier the other way around. The 16v 750 motor is slightly smaller than the 8ver and as such the basket and mounts are smaller/closer together as well. Not saying it cant be done, just saying it will be a chore.

[makenzie71]

well finally got my new sensor location to work and she runs 190~195*f down the highway and running around town yesterday, with lots of idling at red lights back to back, she only got up to about 220*f. A little warmer than I would like but it eases my mind to work on my charging system.