Results of ZX10R Valve Spring Testing - Kawasaki ZX-10R.net
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post #1 of 16 Old 05-21-2007, 06:11 PM Thread Starter
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Results of ZX10R Valve Spring Testing

Results of ZX10R Valve Spring Testing

For testing I purchased 1 new stock intake spring, 1 new stock exhaust spring, and 1 new "race" spring to test on my RIMAC spring tester (see photos) to verify the statements made numerous times on this forum that the "race" springs are actually softer than the stock exhaust springs because presumably the race exhaust cam has less lift and therefore needs less spring.

I can tell you this is simply NOT true and is born of assumptions and guessing, or speculation and not actual testing.

There are 2 spring measurements of interest to engine builders.

Installed height, sometimes called seat pressure or the amount of pressure the spring exerts when the valve is fully closed and the cam is not lifting against it, and then the amount of pressure exerted when the cam has fully lifted the valve open. In this case I am not concerned about installed height, but about the spring pressure when the valve is fully opened.

The results are below. For a comparison purposes I am compressing all 3 springs to 1" inch, about the average height the spring would be compressed at full lift.

Stock Intake 120lbs (Green Paint Mark)

Stock exhaust 84 lbs (Purple Paint Mark)

Race 120lbs (Pink paint mark)

So as you can clearly see the RACE spring is not only NOT softer than the stock exhaust spring, but at 1" inch compression exactly equals the stock intake. The Race and Stock intake springs also look identical, but they are not. Compressing both springs just .050 (50 thousands of an inch more) about the extra lift of the race intake cam reveals that the RACE spring is actually 5lbs stronger than the stock intake.

Stock Intake 135lbs (compressed to .0950")

Race Spring 140lbs (compressed to .0950")

So the race spring is working exactly as designed. Stock pressure up to stock cam lift points, and then greater pressure at lifts greater than the stock intake cam.

Kawasaki use every trick in the book to get the most power out of this engine. They used lightweight titanium exhaust valves so they could use as little valve spring pressure as possible to control these lightweight exhaust valves. Strong valve spring tension must be overcome by crankshaft horsepower and using just 84lb springs on the exhaust side was probably good for a few horses. But that in my opinon is really cutting it close.

I would think you would be safe using the stock INTAKE springs with the race intake cam, but probably safer using the RACE springs with the RACE intake cam, especially if you plan to use the rev extend function of the Power Commander ignition box.

Bottom line, the RACE springs are NOT softer than the stock springs, they are equal to the intake up to the stock cams maximum lift, then stronger than the stock intake at greater lifts. They work just as designed.

For us street riders, I would recommend the race intake with the race springs if using rev xtend, or stock springs with normal redlines and leave the exhaust stock.

JJ
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Last edited by JimmyJam; 05-03-2008 at 12:52 PM.
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post #2 of 16 Old 05-21-2007, 06:51 PM
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now that thar is some quantifiable results if'n i'd ever seen it.

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post #3 of 16 Old 05-21-2007, 10:44 PM
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wow nice job man, Sal from ACE performance said that the race exhaust springs werent any good and they went with custom ones outta japan of some sort i believe.

I wonder what his findings were and how he measured them as well.


now using their race exhaust camshaft which is smaller than stock what would the benefits be????? or would increasing the lift be a better gain? I made my own exhaust cam from a stock intake modified one time and had little results but was worth the R&D I wonder now if i have a more stout motor if i would see more gains with it. That or what about a custom camshaft bigger than the stock intake on the exhaust side?
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post #4 of 16 Old 05-21-2007, 11:06 PM Thread Starter
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Quote:
Originally Posted by garth285 View Post
wow nice job man, Sal from ACE performance said that the race exhaust springs werent any good and they went with custom ones outta japan of some sort i believe.

I wonder what his findings were and how he measured them as well.


now using their race exhaust camshaft which is smaller than stock what would the benefits be????? or would increasing the lift be a better gain? I made my own exhaust cam from a stock intake modified one time and had little results but was worth the R&D I wonder now if i have a more stout motor if i would see more gains with it. That or what about a custom camshaft bigger than the stock intake on the exhaust side?

I haven't got a RACE exhaust cam to measure yet, to compare to the stock exhaust cam, but the RACE intake has .6mm more lift than the stock intake. I like that.

I would imagine the RACE exhaust has more lift, not less, than the stock exhaust. Until I get one to measure, I don't have a clue.

Up until recent years the Japs always used the same 16 springs on all the valves. But recently they have gone to weaker springs on the exhaust (with light weight titanium valves) in an attempt to squeeze a few extra horses out of the engine.

Lack of valve springs at all is one reason why Ducatis make so much power. But alas they do use a little tiny spring to insure the valve stays shut.

Think about degreeing cams and turning the engine over by hand, how much power off the crank it must take to turn those cams at 13000 RPM fighting the valve spring tension. 84lbs on exhaust springs is scary little.

JJ
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post #5 of 16 Old 05-22-2007, 05:56 AM
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From the race kit manual- exhaust cam less lift and duration, maybe it works better on high compression pistons for exhaust velocity?

Camshafts, Sprockets
Camshafts, Sprockets:
Camshaft Duration Lift
49118-0008 (STD) (Intake) 300 9.1 mm
49118-0045 (STD) (Exhaust) 292 8.5 mm
49118-0034 (Kit) (Intake) 310 9.7 mm
49118-0077 (Kit) (Exhaust) 280 8.0 mm
�� Use the kit valve springs (49078-0049) when the kit exhaust camshaft (49118-0077) is
used.
○ Install the kit valve springs facing the rough coiled side (pink paint end) to the retainer.
�� Adjust the valve clearance within the specified value. Intake: 0.15 ~ 0.24 mm, Exhaust:
0.17 ~ 0.22 mm
�� More performance is expected when adjusted from middle value to upper limit between
adjustable range.
�� If you can not adjust the valve timing for racing, install the camshaft sprocket to the
camshaft using the round bolt holes and adjust the cam chain timing according to the
Ninja ZX-10R Service Manual. If you adjust the valve timing, install the sprocket to the
camshaft between the adjustable range of the long bolt holes.
�� Tighten the camshaft sprocket bolts to 15 Nm (1.5 kgfm, 11 ftlb) of torque.
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post #6 of 16 Old 05-22-2007, 06:16 AM
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This is my set up Race inlet cam/stock springs, Race exhaust cam/race springs degreed to 107/104, thin head gasket, stock exhaust- cat removed rebaffled mufflers no exhaust valve, power commander with map etc no dyno run, should be interesting
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post #7 of 16 Old 05-22-2007, 07:09 AM Thread Starter
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Quote:
Originally Posted by technic View Post
From the race kit manual- exhaust cam less lift and duration, maybe it works better on high compression pistons for exhaust velocity?

Camshafts, Sprockets
Camshafts, Sprockets:
Camshaft Duration Lift
49118-0008 (STD) (Intake) 300 9.1 mm
49118-0045 (STD) (Exhaust) 292 8.5 mm
49118-0034 (Kit) (Intake) 310 9.7 mm
49118-0077 (Kit) (Exhaust) 280 8.0 mm
�� Use the kit valve springs (49078-0049) when the kit exhaust camshaft (49118-0077) is
used.
○ Install the kit valve springs facing the rough coiled side (pink paint end) to the retainer.
�� Adjust the valve clearance within the specified value. Intake: 0.15 ~ 0.24 mm, Exhaust:
0.17 ~ 0.22 mm
�� More performance is expected when adjusted from middle value to upper limit between
adjustable range.
�� If you can not adjust the valve timing for racing, install the camshaft sprocket to the
camshaft using the round bolt holes and adjust the cam chain timing according to the
Ninja ZX-10R Service Manual. If you adjust the valve timing, install the sprocket to the
camshaft between the adjustable range of the long bolt holes.
�� Tighten the camshaft sprocket bolts to 15 Nm (1.5 kgfm, 11 ftlb) of torque.

Historically the Race Kit Manual is not written by KHI (Kawasaki Heavy Industries) but has been written by a British race team which is why the wording sometimes sounds like a Brit when you read it. And the ZX7 Superbike Race Manuals over the years have been full of mistakes as well.

That being said, I can concur that the stock and race intake cams measure to the specs you have posted. I have not yet measured a race exhaust cam. to verify those specs, but I will be soon.

It however makes little sense to me to go to a weaker cam and stronger springs. Maybe they are concerned that the stock exhaust springs are borderline weak (I have confirmed that) and they will be using a higher redline with the race ECU. Short of that it makes little sense. Maybe the 8.0 published spec for the RACE exhaust cam is a is a typo in the race manual?

That is the next thing I want to verify myself. What the race exhaust cam really measures out to. If it is less than stock they can keep it.

I plan to use the RACE springs on the exhaust side because I have received my unlock code from Dynojet for the rev xtend function.

JJ
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post #8 of 16 Old 05-22-2007, 07:14 AM Thread Starter
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Quote:
Originally Posted by technic View Post
This is my set up Race inlet cam/stock springs, Race exhaust cam/race springs degreed to 107/104, thin head gasket, stock exhaust- cat removed rebaffled mufflers no exhaust valve, power commander with map etc no dyno run, should be interesting
I had a NASCAR engineer one time draw me up a chart that he claimed would tell you the theoretical perfect INTAKE lobe center for any engine based on 2 factors. Length of connecting rod, and the stroke of the engine. I know what the stroke of the ZX10R is, but have not measured a connecting rod. If anyone has one on a work bench and can measure it from the CENTER of the big end to the CENTER of the little end, kinda of a funky way to measure, then I can tell you what this chart says the intake lobe center should be.

Further more, I can scan this chart and post it for everyone to use.

He states there is not a mathematical way to determine a perfect EXHAUST lobe center, (to many variables) but YES on the intake.

So if someone (Garth maybe?) has a 10R rod lying around and can measure it, we can see how close to 107 this matches up for intake.

JJ
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post #9 of 16 Old 09-15-2007, 02:44 PM
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JJ Wrote:

"...The Race and Stock intake springs also look identical, but they are not. Compressing both springs just .050 (50 thousands of an inch more) about the extra lift of the race intake cam reveals that the RACE spring is actually 5lbs stronger than the stock intake.

Stock Intake 135lbs (compressed to .0950")

Race Spring 140lbs (compressed to .0950")
"

Don't you mean, you compressed them to .950"? I think compressing them to .0950 is way way past coil bind.

Maybe I didn't pick it up in your writeup, what was the pressure of each intake spring at max valve lift for the race cam? I'm not doubting your results, but you only have two data points, valve closed, and .050" open. The 5 pound difference in pressure of the race intake spring at .050" open is only about 3% more, and is perhaps in the margin of error or repeatability for the spring tester. Is that enough to get excited about, given that you only tested one spring? If you saw a large difference at max valve lift I'd probably call this a closed issue.
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post #10 of 16 Old 09-16-2007, 12:01 AM
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