750 oil pump gears on GS1000

[Anonymous]

Has anybody been running a GS1000 on the road with GS750 oil pump gears for a good few thousand miles?
I am about to rebuild my engine after a slight accident (crank twisted) and have some Star racing gears I could fit, but a couple of points have occurred to me:
1. As far as I can see there is no mention of uprated oil pump gears in the description of the Yoshimura race bike. (GS1000 Performance Portfolio)
2. Is there any risk of cavitation, or decrease in pump efficiency, at high RPM?

My bike is mildly tuned, with "stage 1" cams (about .389 lift, not that radical). I do not have a cooler fitted.
Should I fit the gears, or stay with the standard stuff? Will the 750 type gears make any difference.
Any advice much appreciated, don't want any more expense!

[Anonymous]

Cavitation is caused by fluid being pulled rather than pushed. My guess is that cavitation does not apply here. I don't know about any of your other questions. The Yoshi article is interesting though. Notice that he uses the stock head gaskets also. Suzuki designed a pretty good motor to begin with.

[Billy Ricks]

Hap Call can answer your questions.

[Anonymous]

You guys are quick!!

Swanny the fluid here is being pulled (as well as pushed) ---- up from the sump.

Thinking about it, all pumps must pull as well as push!

[saaz]

I also have a street modified 78 GS1000..great choice!

The oil pump gears are probably not crucial for the 1000 as it uses shims. Oil tends to hang around the cams in the shim oil pockets. If you have the gears, may as well put them in.

The best things to do for oil life and engine life is an decent size oil cooler, at least if you run in hot weather. The modified engine runs hotter quicker than standard, and if the rebuilt is good quality the tolerances can be kept tighter if engine cooling is effective.

I have 80,000kms on my rebuilt motor and it runs great still. I rebuilt it at 70,oookms, as I think it had run too hot too often without a cooler. The only problem I may have, but not that great or worrying, is the valve stems seals may have hardened a bit with age (15 years!) so a bit of oils creeps past them.

[Hap Call]

The 750 gears that are often used are from the 4 valve 750 motor which has a different design of oil pump than the two valve motors...I do not think they will fit.

Hap

[Anonymous]

Hap, the gears I have used are Star Racing type. They are identical to GS1000 gears in appearance and to 2V GS750 gears in the nuber of teeth.

I was assured they would fit by the UK's best known GS specialist. I have run the motor with them fitted.

I am now confused. I thought the 1000 and 1100/1150 oil pumps and gears were the same. Anyone got the 4V part no's?

1000 2V pump 16400-49011
driven gear 16331-49990 33T
drive gear 16321-49990 34T

750 2V pump 16400-45013
driven gear 16331-45000 29T
drive gear 16321-45002 38T

[saaz]

The 4V 750 has a high pressure pump, so it is of different design. I did look this up at home in the GS750 manual I have. I think from memory that the various GS models may have different drive/driven gear combinations to allow for the speeds at which they rev. From memory I think that the primary gear ratio on the 750s is different to other models, hence they put in different oil pump gear ratios.

[saaz]

If you do a search on oil and gear and pump there is a previous thread on this.

[Hap Call]

1100 4V pump 16400-49210 superseded to 16400-49220
driven gear 16331-49990 superceded to 16331-49000 33T
drive gear 16321-49990 superceded to 16321-49000 34T

750 4V pump 16400-49220
driven gear 16331-45000 29T
drive gear 16321-45002 38T

According to the schematics from Bike Bandit, the pump on the 2V 1980 GS1000ET is different from the 4V motor:

http://houseofmotorcycles.bikebandit.com/partsbandit/showschematic.asp?dept_id=151163

This pump (16400-49011, superceded to 16400-49020) appears to be more like the pump on the shaft drive motors, but the driven gear (16331-49990 superceded to 16331-49000) is the same part number. The drive gear (16321-49990 superceded to 16321-49000) is also the same.

So, in conclusion, the pumps are different, but the drive and driven gears are the same...at least according to the schematics on Bike Bandit.

This is very interesting... I learned a lot here!

[Hap Call]

Additional info to determine pump speed:

1980 GS1000ET 2V motor:
primary drive gear on the crank 21111-49002 49T
primary driven gear on the clutch 21200-49002 87T

1981 GS1100EX 4V motor:
primary drive gear on the crank 21111-49002 49T
primary driven gear on the clutch 21200-49201 87T

1981 GS750EX 4V motor:
primary drive gear on the crank - unknown
primary driven gear on the clutch 21200-49400 93T

No data on the 2V 750 motor

[Paul]

GSX750 oil pump drive gears ARE identical to the uprated gears from Star Racing, (or Orient Express or any other aftermarket tuners)
But they are from the air-cooled 750.
I used to get them from breakers and they were from the original GSX750. Whether they uprated the gears/pump in later incarnations I don't know.
The aftermarket gears came on the market after the GSX750 - so they were obviously copied & sold as an upgrade. Bear it in mind that all they do is speed the pump up and so increase the oil flow - not oil pressure.
When Pops Yoshimura tuned the GS1000, the GSX didn't exist, so he wouldn't have had the gears available to use!
I have never heard of anybody having a problem with using these in a road engine (no matter how highly tuned)

[Hap Call]

Paul makes a point here but not quite in the way he intended! I believe some of the confusion is from the fact that the US market called all the 2 and 4 valve motors "GS" while the rest of the world called the 4 valve motors "GSX". That gets even more confusing when you consider the air-oil cooled motors that followed our beloved air cooled dinosaurs.

Hap

[Paul]

Yes, I keep forgetting that you guys in the US have to be different!!

[1100ED]

Yes, I keep forgetting that you guys in the US have to be different!!

True oh so true.
Look how we improved the metric system of measurement.