GS750 GS650? Oil Pressure

[renobruce]

Does anyone know what the oil pressure level should be on a GS750 or GS650? I think all the 750's have the higher volume oil pump gears and maybe the 650's too? What does the manual say should be the operating oil pressure? Does anyone have a manual and can you take a look for me? I'm most concerned with the models that have the oil gallery plug UNDERNEATH the points cover, which is some of the 750's and 650's. Any info would be very helpful. Thanks!

[Dave8338]

Does anyone know what the oil pressure level should be on a GS750 or GS650? I think all the 750's have the higher volume oil pump gears and maybe the 650's too? What does the manual say should be the operating oil pressure? Does anyone have a manual and can you take a look for me? I'm most concerned with the models that have the oil gallery plug UNDERNEATH the points cover, which is some of the 750's and 650's. Any info would be very helpful. Thanks!

I'll check tonight and let you know...I hope! :-D

[Tarbash 27]

suzukicycles says "Oil pressure: 1.42 psi @ 3,000rpm" for a 2 valve 750. Mine is about 1 psi at idle after fully warmed up, and about 4 psi at around 5,000 rpm, thanks to your gauge. Thats from what i can remember roughly. My guesstimates might be a little off.

[wharrah]

suzukicycles says "Oil pressure: 1.42 psi @ 3,000rpm" for a 2 valve 750. Mine is about 1 psi at idle after fully warmed up, and about 4 psi at around 5,000 rpm, thanks to your gauge. Thats from what i can remember roughly. My guesstimates might be a little off.

Does your gauge "peg' past the 15psi indication and stay there for any length of time? If it has ever done that, did it come back down ok, with no damage to the gauge?

I'd be interested in knowing if the indications for anyone with a 30psi gauge are in a similar range too. I'm nosy.

[Nessism]

Plain bearing crank motors, like the 650G (shaft model), require quite a bit more oil pressure than a roller bearing motor 650e (chain model). Make sure you are comparing apples to apples.

[wharrah]

Plain bearing crank motors, like the 650G (shaft model), require quite a bit more oil pressure than a roller bearing motor 650e (chain model). Make sure you are comparing apples to apples.

I thought that all of the GS series engines except for the 450 all had roller bearings? Is this not true??:shock:

[Tarbash 27]

Does your gauge "peg' past the 15psi indication and stay there for any length of time? If it has ever done that, did it come back down ok, with no damage to the gauge?

I'd be interested in knowing if the indications for anyone with a 30psi gauge are in a similar range too. I'm nosy.

When I first start my bike and the oil is cold, i get very high oil pressure. It usually pins it on choke because it revs to about 4,000 rpm. Pressure slowly drops as the oil warms up because it expands. But once the bike is fully warmed up, it goes no where near 15 psi. maybe 6-7 psi at high rpm.

[renobruce]

Plain bearing crank motors, like the 650G (shaft model), require quite a bit more oil pressure than a roller bearing motor 650e (chain model). Make sure you are comparing apples to apples.

Do you know by how much? what should the pressure be? What's the manual say for the shafty?

[renobruce]

I just got off the phone with wharrah... he has the 650 with plain berings. His manual states 43-78 psi @ 3,000 rpms. So now the question is: which GS's came with plain bearings?

[Hap Call]

I just got off the phone with wharrah... he has the 650 with plain berings. His manual states 43-78 psi @ 3,000 rpms. So now the question is: which GS's came with plain bearings?

All the 16 valve 750 motors have plain bearings, all the 8 valve 750 motors have roller bearings.

Hap:-D

[wharrah]

oil pressures for 750s sought

I just got off the phone with wharrah... he has the 650 with plain berings. His manual states 43-78 psi @ 3,000 rpms. So now the question is: which GS's came with plain bearings?

Actually, Bruce and I found that my CLYMER manual for the 1981-1983 GS650 Suzuki FOURS states:

All CHAIN-DRIVE models (GS650) have low-pressure high-output pumps, and run from 1.42-7.11 psi @3,000 rpm.

Then it states:

All SHAFT-DRIVE models (GS650) have high-pressure oil pumps. Normal oil pressure for these is 43-78psi @ 3,000 rpm.

I was totally under the impression all GSs had roller-bearing mains... what a revelation. Now we're wondering if the GS750s are similar to the 650s in this respect.

Anyone know if the oil pressures match these based on bearing type? :? (edit: just saw the post on 8 and 16 valve 750s... wondering if the pressures printed in that bike model's manual match these...)

I'm always learning something here.

[renobruce]

All the 16 valve 750 motors have plain bearings, all the 8 valve 750 motors have roller bearings.

Hap:-D

So it seems maybe the indicator is whether the oil gallery bolt is above and behind the ignition cover = roller bearing and below the ignition cover = plain bearing?

[Nessism]

Simple way to tell is look at the cam caps on the valve cover - round is 8 valve, square is 16.

[Dave8338]

WOW...late to the game as usual, but have learned a pile. I was happy to find that the book states 43-78psi on the shaftie, this comes as a pleasent surprise, BRING ON THE REV's....

[Hap Call]

It should be noted that the oil pumps are the same for the 16 Valve GS1100 and the 16 Valve GS750. Also, the oil pump gear sets are the same for the 8 valve GS750 and the 16 Valve GS750.

Hap