Oil cooler on an '80 750?

[chef1366]

Where does it take oil from and return it to?

I pm'd you some pics

[makenzie71]

Could you post pics? I've been trying to find info on this on the forum with no luck.

[reddirtrider]

Usually the oil system is in this general configuration.

sump -> pump -> filter -> engine oil passages

If you add a cooler in the configuration that I believe you suggested:

sump -> pump -> filter -> engine oil passages

filter -> clutch basket or stator (same as sump)

(Sorry about the diagram but I can't space the second line over to the filter with this posting system.)

You've effectively removed lubrication from the engine.

I could be wrong on what you're suggesting however.

Quite a while ago we went into great detail on the lubrication system on an 1100 and how to add a cooler. I'll see if I can find it.

[chef1366]

The oil cooler may be sold though. I'll let you know.

[posplayr]

What he said

+1 what he said.

You can't just take oil away from the system and dump it back into the engine where ever you like. Do some research to figure out the standard method to plumb a 2nd gen 750 is. Didn't the 750 Katana come with an oil cooler for certain markets? Figuring out how they did it would be a good start.

I have not pursued the GS750 cooler plumbing, but it is entirely possible to do it wrong and by pass or render ineffective your oil filter.

The manuals show a schematic of the oil flow. Understand it.

Pos

[Nessism]

Chef's photo shows a cooler for an 8v engine, the 16v 750 is different and can not be plumbed the same way.

The 16v 1000/1100 have oil port access on the bottom front of the engine cases - maybe in the oil pan, not sure exactly. Maybe the 750 is similar?

[chef1366]

You can tap into the two bolts on each side under the oil flter cover and plug the left port under the cover. I do believe an 1150 cover will work but you'll lose the oil sensor.


I made a plug out of a bolt with rubber washers and washers and holding it together with a nut. Just pop it in the port and install cover. Forces oil out the bottom left tap and the bottom right is the return.

[posplayr]

cooler

Chef's photo shows a cooler for an 8v engine, the 16v 750 is different and can not be plumbed the same way.

Ed, while generally this type of adapter is used on the 8V almost all of the Japanese 16V bikes do it the same way. Check out Katman's photo gallery almost every bike from Japan has the oil cooler lines on 16V motors running back under the carbs.

The only thing I can figure is it looks like a side mounted Samurai sword , else why not use the stock setup?

If you capture part all or part of the flow , send it to the cooler and then return it to close to the same place it will continue on. The problem as you know is getting the neck right so you don't pypass too much and render the cooler inoperative (no diffferential pressure across the two ports).

I remember seeing a bunch of post 83+ GS700/750 oil coolers that all seemed to have the same banjo configuration as the GS1150 a simple check of the micro fiche and the manual should confirm. Why re invent the wheel as you mentioned before.

A link of OEM oil coolers

http://www.thegsresources.com/_forum/showthread.php?t=130435

I don't remember but I don't think my 81 GS750 has banjo bolts installed at the oil filter. In that case the 8V adapter approach maybe best.


Here is the warning I posed before about trying to return to the oil filter cover.

http://www.thegsresources.com/_forum/showthread.php?t=122837

Pos

[reddirtrider]

Chef's photo shows a cooler for an 8v engine, the 16v 750 is different and can not be plumbed the same way.

The 16v 1000/1100 have oil port access on the bottom front of the engine cases - maybe in the oil pan, not sure exactly. Maybe the 750 is similar?

Correct.

Here's what I know.

1) The 16v 1100/1150 motors have oil outlets on either side of the oil filter cover. They use different oil filter covers, however. The 1150 cover has ports nearly blocked off to divert oil to the cooler, while the 1100 cover doesn't (since it has no cooler).

2) The 750ES model uses an oil cooler and has ports on either side of the oil cooler much the same as the 1100/1150 motors.

Here's what I don't know.

1) If the 750E motor has the same ports on either side of the filter.

Here's speculation

1) The 750ES oil filter cover has ports blocked to divert oil to the cooler in the same way the 1150 cover does it.

2) If this is true, and if the 750E motor has the same ports on either side of the filter cover, then simply swap the filter cover on your E for an ES, and hook the cooler to the oil ports.

[Nessism]

The '83+ 750/700 engine is a 3rd generation GS engine and significantly different from the 2nd generation 750 engine. I don't know how the oiling system differs other than I know the later engine uses external oil lines instead of internal passages which can lead to head gasket leak issues.

[posplayr]

80-81 gs750e 16v

Here's what I don't know.

1) If the 750E motor has the same ports on either side of the filter.

80-81 GS750E 16V doesn't have any ports and the oil pressure sender is in the middle of the filter cover.

Pos

[reddirtrider]

The '83+ 750/700 engine is a 3rd generation GS engine and significantly different from the 2nd generation 750 engine. I don't know how the oiling system differs other than I know the later engine uses external oil lines instead of internal passages which can lead to head gasket leak issues.

If that's the case, and there are no external oil ports on either side of the oil cooler - then my hypothetical solution won't work.

Just one more reason to be thankful that the 750 sitting in my garage is an ES.

[gearhead13]

This is what the front of my engine looks like:
Under the chrome cover is the oil pressure sensor and an oil temp sensor. The temp guage is not accurate, it shows 100C after 5 min idling

[Billy Ricks]

Here are the pages covering the lube system on '83 and up 700/750 models.

[makenzie71]

On bikes designed with coolers from the factory...like the ES and the '83+ models...that's great, but for a 1981 model it's kind of pointless.

I've checked: My bike does not have ports aside the filter cover. One of the bolts under the pan may be a potential return but I don't believe any of them are plugs sans the drain...and I'm leery of having cooler lines UNDER the engine for obvious reasoning.

The USDM 16v 2nd Gen engine does NOT use the same kind of mounting for an oil cooler as the 1st gen engine, UNLESS it requires drilling the case in the same general location...which I am unwilling to do.

Here's the thing: I feel I really need an oil cooler. Temperatures exceeded 290*f while in traffic today. Now, I do not take my sensor's word as it is...I admit, the temperature reading is from a cooling fin, between the cams, so it is picking up a little more heat that usual, but I am not comfortable with what I am seeing.

I have a cooler kit for an 8v engine...if someone knows of a magic way to make it work with the 16v engine then fricken sweet I'll do it. Otherwise, I would like to sort out something else for the sourcing oil and where should it be returned.