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Speed Freak
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Discussion Starter · #1 ·
Hi all, thought I'd share this to anyone who was looking to raise their oil pressure.....

Oil pressure is regulated threw the relief valve in our engines, most all are found right on the bottom of the motor in the oil pan. These relief valves are a simple ball or collar and spring set up that has a certain pop off pressure. Raising the spring pressure will raise the amount of pressure it takes to over come the spring which equals more oil pressure

All you need to do to slightly raise the oil pressure is shim the spring which entails dis-assembling the relief valve and adding a small washer to the set up

Here is the Relief valve out of my zx-12r along with a snap ring pliers



A closer look at the relief valve, first remove the snap ring and pull the assembly apart



Here is everything in the system. Housing, collar, spring, spring holder and circlip


Here is a washer that is just the perfect size diameter wise.



after cleaning the assembly reinstall everything but add the washer to the top of the stack



and here is the stack with the installed circlip




NOW VERY IMPORTANT!!! I do not know how much pressure this will adjust the oil pressure with a given washer thickness so its a trial and error... I'm going to do a before and after test on my 12r when its all together but no hard data.

Hope this helps anyone who is looking to raise their oil pressure when needed! :thumbsup:
 

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Will raising the pressure use more engine power to pump the extra oil? If not, why wouldnt Kawasaki have that higher pressure already? what would the draw back be?
 

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Speed Freak
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Discussion Starter · #3 ·
in theory yes it would draw slightly more power from the motor since its gotta create more oil pressure. I'm doing this because oiling a big stroker motor is very important to me. I've even tapped and installed a plug to the counter balancer oil so not to waste any oil going to the mains.

Trochoid oil pumps are VERY efficient oil pumps though and it doesn't take much to make massive amounts of pressure though so slightly raising the oil pressure a few psi shouldn't be to much of a concern.

In my application oiling is more important than a 1 horsepower draw, I'd prefer the motor to last
 

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Speed Freak
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Discussion Starter · #6 ·
as soon as I get my 12r going I might run the stocker for the break in oil and then once I'm done breaking in and change oil I'll pull the pan and do the test again.
 

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I did exactly this to my Yamaha FZR400 race bike engine the last time I had it apart. If you can figure out how much the spring is preloaded (measure its free length and then the compressed length) you can figure out roughly what percentage that the washer would increase the pop-off pressure. In my case, it was something like 10% - 15%.
 

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If you doubled the oil pressure, maybe that would be an issue, but a minor increase should not be a problem.
 

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pretty common mod to the zx-11 engine.

there are dangers of too much pressure in the oil system, though. if simply more oil pressure is better, wouldn't the factory have spec'd a stiffer spring? No difference in cost to them... :dontknow:
 

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shnitz racing sells a regulator to do this for around $80. good mod for big bore or turbo. it raises oil pressure from 75 psi to 110 psi. i was told that going over 120 psi or so could cause a problem. blowing out the sealant that seal the oil gully's where the crank case halves meet, so i would hook up a oil pressure gauge and make sure your not too high.
 

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Garth, whats the thickness of the shim?

A higher regulator pressure would require that the engine be warmed up more than usual or you will see those higher pressure spikes.

How hard was it to plug the oil galleries for the balance shaft?
 

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Speed Freak
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Discussion Starter · #13 ·
Garth, whats the thickness of the shim?

A higher regulator pressure would require that the engine be warmed up more than usual or you will see those higher pressure spikes.

How hard was it to plug the oil galleries for the balance shaft?
I'll measure it tomm, I might have a way of checking pop off pressure tomm on the bench, I rigged up a way how to test fuel pressure regulator's release so maybe I can do the same with this and do a before and after.... :thumbsup:
 

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^^No Bike Bum^^
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pretty common mod to the zx-11 engine.

there are dangers of too much pressure in the oil system, though. if simply more oil pressure is better, wouldn't the factory have spec'd a stiffer spring? No difference in cost to them... :dontknow:
i agree it is common on the ZX-11 motor for this type mod..

yes too much oil pressure is bad, due to blow out seals and causeing unwanted leaks... however, a slight boost in pressure will help keep the motor lasting longer with a little less wear and tear.. the factory does just enough for it to work properly and do its job.. like the air filter for example.. how much more would it cost to go ahead and throw in a K&N filter than use a cheap stock filter.. bet K&N would give them a heck of a deal on the filters and not cost the consumer $15-$20 more on the bike asking price. (note this is only my opinion) :hello:

oh yeah... nice post Garth
 

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Speed Freak
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Discussion Starter · #15 ·
ok guys I did some tests today.... stock oil pressure relief valve pops off at 62.5psi roughly.... the shim (washer) I have shown above measures 1.58mm thick (or 0.0622")

with that shim installed it pops off at right at 85psi! so almost 20psi of pressure for thwat 1.58mm thick washer.... sounds good to me!!!
 

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now that is on the ZX-12 right... anyway u could do the test for a 1st Gen 10R??
 

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Speed Freak
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Discussion Starter · #17 ·
I might have a bud who has some spare engine parts I might be able to get one and test it, most of the valves ive seen are pretty similar in shpae and size though.

the 12r reliefe valve is the same part number for a buncha other bikes like 6r's 11's zx7s, zx9s and on and on....

I'll try to get one from someone though

or if anyone has one laying on a bench somewhere and wants to send it to me let me know!
 

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I might have a bud who has some spare engine parts I might be able to get one and test it, most of the valves ive seen are pretty similar in shpae and size though.

the 12r reliefe valve is the same part number for a buncha other bikes like 6r's 11's zx7s, zx9s and on and on....

I'll try to get one from someone though

or if anyone has one laying on a bench somewhere and wants to send it to me let me know!

I got a stocker I can drop off to ya, but it is probaby the same as the 12.
I shimmed my 05 .120 over stock and run 80psi hot using straight 50wt. I broke a new autometer 100psi gauge by revving a cold motor, it stuck on 25psi when I turned the bike off so Im guessing it made 125psi cold?
I just finished a rebuid but didn't document it with photos. I can post some pics of the finished engine if anyone wants to see them.
 

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Speed Freak
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Discussion Starter · #19 ·
yeah man, if ya could bring one buy I'd like to do a quick bench test just to compare. hit me up!
 

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Speed Freak
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Discussion Starter · #20 ·
*** UPDATE ***

ok 1 I'm stupid, the valve in the pictures above is actually for a jet ski motor STX15f that was dis assembled, I was poking around in my 12r stuff and I found mine!

ok so they are both pretty much same in dimensions but the 15f's has a 14mm thread and the zx12r has a 12mm thread

I rigged up the valve to a pressure gauge and I got the following readings

Stock valve no shim read 55psi
Shimmed valve read 75psi

so it looks like the 1.58mm thick washer bumps you roughly 20 lbs...

I also tried to stack 2 washers and it was giving me inaccurate readings but was over 85psi, I honestly don't want to go over board on oiling but I think the extra 20 psi should defiantly be a great improvement in my application.

hopeful my bud Shameless can drop off a stock 10r one I can do the same experiment on just to let us 10r guys know what exactly were looking at.
 
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