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750 oil pump gears on GS1000

  • Thread starter Thread starter Anonymous
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Anonymous

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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!
 
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.
 
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!
 
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.
 
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
 
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
 
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.
 
If you do a search on oil and gear and pump there is a previous thread on this.
 
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!
 
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
 
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)
 
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
 
Yes, I keep forgetting that you guys in the US have to be different!!
:lol:
 
Paul said:
Yes, I keep forgetting that you guys in the US have to be different!!
:lol:
Click to expand...
True oh so true.
Look how we improved the metric system of measurement. :lol:
 
So to sum up, it would seem that fitting these Star Racing gears is as valid on the 1000 as on the 1100.

My question's are:
1. Is there any possibility it could do more harm than good?
2. Would I be just as well served by fitting the stock items?
3. Is it necessary?

Thanks for everybodies input so far. :)
 
brit7.11 said:
So to sum up, it would seem that fitting these Star Racing gears is as valid on the 1000 as on the 1100.

My question's are:
1. Is there any possibility it could do more harm than good?
2. Would I be just as well served by fitting the stock items?
3. Is it necessary?

Thanks for everybodies input so far. :)
Click to expand...

1. There has been some debate on if this is a good upgrade. One guy believes that it spins the oil pump too fast, leading to premature failure. Another member has stated that he has seen several failures in bikes that use the gears but cannot confirm if it is the gears that are causing the problem or something else.

2. Several of the top motor builders use the 750 gears - Greg Cope and Byron Hines to name a couple. They are generally considered the best in the business and have faith in them. Like Paul said, you will have a increase in flow but due to the design of the oil system you will see little or no increase in pressure. That is not a bad thing - just the way it is. It will get more oil up to the cams where there are no roller or needle bearings supporting the cams...that is were you want it.

3. Is it necessary? If you are running stock or mild cams with stock valve springs, it is not really necessary, especially with the shim and bucket valve arrangement you have. But it sure can't hurt. I have been running them for three years with no problems in my 16 valve motor.

Hap
 
I went back and asked Kim Barringer at Carolina Cycle what was the deal when we saw so many sheared teeth on the overdrive pump gears in the late 80`s. His answer was that it was improper heat treatment of aftermarket gear sets. His answer was also both star and ape had a problem so as a whole all of us quit using them. He thinks possibly at that time they had a gear set that was even a higher drive ratio than what is used now. I asked his opinion of using them now...several do...he just uses external oiling kits on engines and will if asked put the gears in. To his knowledge there have been no recent failures with the current gears. Hope that clears that up a little. Also his opinion is without high seat pressure on the valves stock is fine...thats mine too. I`m not saying Kim is the best or anything just seen a lot of engines and been around a long time. He does excellent work but my grandpa moves faster 8O I`m in the process of doing a engine now...I`ll probably run the gears and pray its right. 8O
 
I don't think there is a risk of anything going wrong if the gears are decent quality. The GSX motor probbaly needs more oil due to the different valve train (adjustable rockers) exposing any oil problems to the cams etc. If you have the gears put them in...a side benefit may be more oil cooling effect from a bit more oil circulating. I do notice that when you rev the motor hotter oil comes through the oil cooler than at idle, so it is probbaly removing more heat than standard. Welcome to an oil cooled motor!
 
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