750 Oil pump in an 1100

[Anonymous]

I've seen several references here about using the oil pump from a 750 in an 1100. Is this as straight forward as it sounds (no shims, machining, beating with a large hammer, ritual sacrifice, ect..)?
I'm in particular interested in doing this with my 82 1100E.
Is there any possible gotchas involved? Too much pressure/flow causing problems?

Thanks.

[earlfor]

Re: 750 Oil pump in an 1100

I cant offer any info about the parts fitting together, but I can tell you that the GS750 series went from an all ball bearing engine in 1979 to a plain bearing engine in 1980 and afterwards. For 1979 and earlier, the oil pump was very high volume and very low pressure to match the ball bearing engine. 1980 on was a low volume, high pressure oiling system to match the subsquent plain bearing engines. Even if it fits perfectly parts wise, you need to be very sure youre installing the correct TYPE of oil pump that matches your engine requirements.

Earl

I've seen several references here about using the oil pump from a 750 in an 1100. Is this as straight forward as it sounds (no shims, machining, beating with a large hammer, ritual sacrifice, ect..)?
I'm in particular interested in doing this with my 82 1100E.
Is there any possible gotchas involved? Too much pressure/flow causing problems?

Thanks.

[Anonymous]

Just curious! Is there a good reason for forcing 40 lbs of oil pressure thru an engine designed for 3 to 5 lbs? I've heard of this modification for years, but so far I haven't found the reason. Full race or turbo engines would be exceptions.

[Anonymous]

I can't seem to locate the post(s) anymore but I was sure I'd seen it here. I just remember it being presented in a positive manner and that it seemed a logical thing to do.

But ya, know sometimes all the other lemmings get in the way and just aren't sure whats what.

Really though, if anyone remembers this and feels it's a reasonable modification, can we here from you.

Thanks.

[earlfor]

Ball bearing engines do not require high pressure, but they do require high volume. Plain bearing engines require high pressure, but not a lot of volume. So, I guess the answer is NO!
An oil pump MUST be matched to an engine design and its requirements.

Earl

Just curious! Is there a good reason for forcing 40 lbs of oil pressure thru an engine designed for 3 to 5 lbs? I've heard of this modification for years, but so far I haven't found the reason. Full race or turbo engines would be exceptions.

[saaz]

Putting the early GS750 oil pump gear in a GS1000/1100 does not make it a high pressure engine. It pumps a bit faster and raises the oil volume. I have the relative teeth sizes written down at home in my workshop manual...it is something like 10% increase or so.

[Anonymous]

I can't seem to locate the post(s) anymore but I was sure I'd seen it here. I just remember it being presented in a positive manner and that it seemed a logical thing to do.

But ya, know sometimes all the other lemmings get in the way and just aren't sure whats what.

Really though, if anyone remembers this and feels it's a reasonable modification, can we here from you.

Thanks.

Perhaps you are referring to just changing the ((OIL PUMP GEARS TO GEARS FROM A 750)) THIS MOD IS SUPOSED TO GIVE A PROX 30%INCREASE IN VOLUME. tHIS IS A COMMON AND INEXPENSIVE MOD AND WILL SERVE YOUR TOP END WELL BUT IT ISNT NECESSARY

[Hap Call]

Here is the deal: The oil pump on the four-valve GS1100 and the four-valve 750 are the same pump (even the same part number from Suzuki). The 750 pump has a lower ratio gear so that it spins faster to produce more oil pressure to the plain bearings on the bottom end. It is a simple bolt-in job to replace the oil pump gear. You do have to pull the clutch basket to get to it.

As far as higher oil pressure, Scotty is on the money when he says that increases oil volume...it does not make a sufficient difference in oil pressure since the oil system is designed as a low pressure system. I saw only about a pound or two increase in pressure.

There is some debate that the pump will wear out faster, but I have been advised to do it from such shops as Ward Performance and Cope Racing. I have it in mine and have not had a bit of problem.

Again, Scotty is correct in saying that it is not necessary on a stock bike. If you do go with higher lift cams I would definitely look into it.

Hap

[massakins]

A common weakness in the 4v top end is rocker arm and cam lobe wear. Not a big deal on stock motors, but as spring rates, seat pressures and valve lifts increase it becomes a problem. GS750 oil pump gears from the '79 and earlier 2v GS750 is the first step. Next step are rocker arms that have been welded on the cam lobe contact surface and ground back to their original profile; this results in a much harder surface than OEM.

Remember, oil has 5 functions in our vehicles. It serves to 1)prevent moving parts from making metal to metal contact, 2)cool the parts by transferring heat away from the source, 3)seal mating surfaces that aren't flat (on a microscopic level), 4)cleans the engine by flushing away dirt and contaminants and 5)provide a cushion when transfering load.

Kind of makes you feel guilty about belated oil changes, huh?

[Anonymous]

I guess I'll jump in now,
Hap said to use the 4 Valve 750 gears and Massakins said to use the 2 Valve parts. Which ones should we be using? I figure I'll get myself a set since I'm already on the lookout for a top end oiler as well as an oil cooler. Both of these should lower the pressure a bit so I may as well get a quicker pump.

Steve

[massakins]

To further cloud the issue, Hap and I put the 2v gears, or an aftermarket equivalent, in one of his motors. Clear as mud?

[saaz]

I have a GS1000 and GS750 workshop manual, but they dont give the gear sizes (I counted my GS1000 years ago - 33 to 34 teeth). I am guessing a bit, but the GS750 2 valve is geared down a bit in the primary reduction ratio (crank to clutch). It revs more for the same speed. To get oil volume through the motor at the same revs, the 750 oil gears have to turn it faster to achive the same oil pump speed for the same revs as the 1000. The gsx4 valve is a high pressure plian bearing motor, so woul have to have a high pressure pump.

In normal use an oil cooler would be the first thing to do, then pump etc.

My guesses!!!

[massakins]

I stand corrected. Hap says they were 4v gears. The gears I've used from the 2v GS750 motors have 29t on the pump gear and 38t on the clutch hub gear. This compensated for the different primary drive ratio on the GS750 compared to the GS1000/1100 to restore the pump speed.

[saaz]

This would increase oil volume a fair bit.

Out of interest, what are the 4v gears in terms of sizes?

[Hap Call]

If you go to Bike Bandit and look on the parts drawings the parts description will have the gear tooth count for the primary gears and oil pump gears.

When we were putting my engine together, massakins was modifying a dragbike frame and installing a turbo on his GS1000L. It was a fun and interesting experience. I learned tons from him. He worked for several years in a bike shop while working on his mechanical engineering degree. Let me tell you, this guy knows his stuff. Very much a detail kind of guy. Not only that but his family is great also!

Hap