Oil cooler project for '81 750e

[GregT]

Okay, I'm curious. I was interested in the oil cooler thing for a while and finally decided it just doesn't matter on the 8v engine. Where is the benchmark at which an oil cooler might be a good idea? I'm rocking a 1979 GS550. I use Kerker pipes, shortie pods, retrofit electronic ignition with slight advance, 10% ethanol in my fuel (thanks a lot CA), and I twist it up close to 5 digit rpm in 100-110 degree temps as well as sitting at some streetlights. I'm still in the zone without an oil cooler, imo. Or would it make a difference for me? I think knowledge of the point at which the cooler becomes worth having might be useful to the OP and me. "Never" is an acceptable answer.

In my experience, the 550 has a very good fins to capacity ratio - ie it's well cooled as stock. The low pressure moderately high volume oiling system on the roller motors works well too. The ethanol - if it's jetted correctly - should actually help cooling also. So a probable never...

The 16V plain bearing 750 is just plain awkward. It suffered from low pressure as introduced - which was fixed to a certain extent in later versions. But oil gallery size and design are against it. Fitting a cooler has drawbacks incl as has been noted, pressure drop. The GSXR's did it right with a separate pump for the cooling circuit. I've noted here before that i've seen them used in speedway TQ's with a 3 stage external pump and cooler - and even with MUCH higher pressure than stock they've still done rod bearings...
Use them gently and change the oil frequently and they last acceptably.

[GSCafe]

In my experience, the 550 has a very good fins to capacity ratio - ie it's well cooled as stock. The low pressure moderately high volume oiling system on the roller motors works well too. The ethanol - if it's jetted correctly - should actually help cooling also. So a probable never...

The 16V plain bearing 750 is just plain awkward. It suffered from low pressure as introduced - which was fixed to a certain extent in later versions. But oil gallery size and design are against it. Fitting a cooler has drawbacks incl as has been noted, pressure drop. The GSXR's did it right with a separate pump for the cooling circuit. I've noted here before that i've seen them used in speedway TQ's with a 3 stage external pump and cooler - and even with MUCH higher pressure than stock they've still done rod bearings...
Use them gently and change the oil frequently and they last acceptably.

Thanks Greg. I know how to calculate for ethanol. (fun with turbo, but that is another story) It is just that it is *up to 10%* so sometimes more ethanol, sometimes less. Never mind that ethanol is not good for my rubber parts. I think it runs me lean sometimes. I try to stick to specific gas stations. I'm tracking with you. Probably no need for oil cooler without internal mods.

[Prescot]

Not exactly came across a video on youtube on gs750 and it looked like Suzuki techs working on a prototype or experimenting but in was all in Japanese so couldnt be sure.

looked like it ran from the filter cover>oil cooler> back to crank case.

Think will pass on this even though the oil cap gets hot was riding in stop and go beach traffic without any problems, may just think about changing the oil more often.

[dorkburger]

NJ beach traffic can be a beast... Sound like your best bet is avoid the cooler..... and stay off of Rt 35 /36.....