Thanks for posting up! It's nice to see the differences, power curve wise when its adjusted differently!

Added more details to original post.

Thanks again for all the info and help Jerry!

I only ran the K&N with the stock carb, before the HRD build.  I started with a Lectron 44 and a 4x8 Uni dual layer foam filter.

600 main was about ideal running China Wall last winter.  620 would not pull the hill in 4th, but 600 would.  This was then F&L 111 w/Amsoil Dominator 40:1.

where did you have it dynoed at?

Well, they didn't account for the guys that thought 10 more turns would give them more power...after all, it is a POWERvalve 

"so long story short, Suzuki Engineers knew their stuff when the designed our power valve. In fact the owner of the company was very impressed with how Suzuki over engineered the spring"


Wish they spent more time on the transfer ports where it would of really counted

I had posted this information on a few sites, so I thought I would put it up here.

Alright, I've read all over about the power valve issue.  Does it work?  Does it make a difference?  Any dyno hard results? etc., on and on.

Well I have some dyno charts for my setup and we specifically were playing around with the PV setting.  From blocked off thru 1.75CC (counter clockwise).

The following charts are for a HPR#19, taper bored TM38, dune porting, open intake, VF2 reeds.  The charts show torque and I will not post Q vs HPR pipe HP numbers because those always get into pissing matches.

I just wanted to show that on the 500, the PV does impact your power curve.  I've highlighted all curves since they are hard to read if I didn't.

FYI... I've heard and it makes sense to me that based on oil temp, the PV will open at different points.  My test results for my engine seemed to like 1CC PV setting when running the Hall HPR#19.

These are Torque numbers only as I don't want these threads to start any HP wars.

PV blocked closed:


PV set to 1.25CC (Q pipe recommended setting):


PV set to 1.50CC:


PV set to 1.75CC:


PV set to stock 1.00CC (best for my bike):


So in short, if your a drag racer running only WO, then blocking it off closed won't impact top end RPM / Power.

If you do anything else, it can greatly impact your power below 6k RPM.... you can even screw up and set it to 1.75CC or more and it will kill your top end.

EDIT 10/16 - Adding run info.

These were all from Hall's dyno in Phoenix, AZ on June 27th, 2011.

My Setup:

500 Fanatic - HRD porting (HRD rebuild completed 8/2010), Ears re-inforced
Head - Squish fixed & o-ringed
Trans - M102
B8ES .020 gap plug w/5k plug cap
OEM stator, coil, ECU, stock timing
HPR#19 Pipe
VP110 w/927 @ 20:1
TM38 bored to 41mm carb w/640 main
Open Intake w/ 4x8 Uni Dual Layer w/Outerwear
Q cut piston
Vforce2 reeds

Dyno Info: (Dyno tires used, Absolute Pressure: 28.5 in-Hg, Air Temp: 90.5* F (Outside temperature in Phoenix was 115* F), Humidity: 27%, Altitude: 1100 ft; engine warmed to same CHT for each pull set, multiple pulls taken to confirm curves)

Jerry Hall is adding a little more information for those that may have trouble understanding the graphs and what effect the power valve closing has on the power curve. 

Graph # 1
Pale green line is the result of the power valve (PV) being closed through the whole RPM range

Graph # 2
Wide Blue line is the result of the PV closing @ 6400 to 6500 RPM

Graph # 3
Wide Pink line is the result of the PV closing @ 7300 to 7500 RPM

Graph # 4
Wide Pink line is the result of the PV closing @ 7600 to 7800 RPM

Graph # 5
Wide Green line is the result of the Optimum setting where the  PV closes @ 5750




I also have some graphs of some PV tuning on a LT250R Suzuki.  I will try to post them in the next few days when I get them transferred from the dyno computer. 

 

I do not know what the stock closing RPM was.

You are right, every engine's power valve governor assembly operates slightly different.  Transmission oil viscosity affects the closing RPM.  We see different closing RPMs on the dyno when doing many back to back runs due to the change in transmission oil temperature.

The optimum closing RPM does need to change with different pipe and porting combinations.  5700 RPM was the optimum point for this porting/pipe combination.

If you look closely at the 1st dyno graph one can observe where the two dyno curves cross at about 5700 RPM.  One graph the power valve was closed the whole run and the others the power valve stayed open until 7300 and 7600 RPM.

..........A setting of 1 turn (5700rpm) with a PT pipe would have a dyno run that looked like 1.25 turn with a Q pipe. You held the PV open to long

I am not am not quite sure of what you are asking. 

Different pipes may need to close at different RPMs to optimize the power curve, but one turn on a particular engine will always close the valve at the same RPM regardless of of the pipe that is installed.

The effect that the Suzuki power valve has on the power characteristic is for a completely different reason as the effect the the power valves that change the port timing and blow-down area on most two stroke engines.

The Suzuki power valve changes the helmholtz resonance.  The engine thinks the engine has one exhaust system at the lower RPM and then switches to a shorter exhaust system when the valve closes.

Power valves that change the timing and port area have multiple reasons that they change the power characteristics.  The change in port height (port duration) affects the tuned length of the pipe. 

A Low port (short duration exhaust port) makes the engine think that the pipe is long and turned to produce power at a low RPM.  As the power valve raises, the timing edge of the exhaust port makes the engine thinks the pipe is being shortened and will produce more power at the higher RPMs.

At this point of comparison of the Suzuki PV and timing/area type valves, the valves effectively change the length of the exhaust system.

The Suzuki valve essentially changes exhaust systems on a given porting scheme when the valve closes.  It puts a torque pipe on an over ported cylinder at lower RPMs and puts a short pipe at power valve closing  on a cylinder that is hopefully ported to match the high RPM pipe.  The Suzuki valve will not perform as much magic on the power curve as a timing/area type valve.

The power valves that change the timing and area of the exhaust port more closely simulates a mildly ported cylinder matched up with a long torque pipe at lower RPMs.  As the RPM increases the porting is gradually increased to match an exhaust system that is gradually being shortened.  When this type of valve is operated properly, a much wider power band with more peak power can be obtained.

Regardless of which type of valve is used, the basic pipe design has the major influence on the power characteristic of the engine.  You cannot put an ultra high RPM pipe on an engine with a LT type power valve and try to set the valve to produce a ton of power at the lower RPMs as believed by so many engine and pipe builders.  Proper testing will make this fact very obvious. 

Hey Jerry, one item missing what year cylinder was he testing? 87 or 88 and up?  Now I would like to go back and re dyno myself with different Spring tensions, when I did testing my PV was set at 2 turns, due  that Mat Shearer stated that his testing the longer the P/V stayed open the more low end / mid torque, I guess is come down to how the pipe design is to work with the P/V, Again Thank You Jerry for your time and patience for doing this.

The 3 graph shows the inconsistency of the Power Valves closing RPM made back to back over a time period of 30 seconds.  The zig zags are produced when the valve closes at a RPM where the closing point is not at the optimum RPM.