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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 small reed Top end ,HPR#19, taper bored TM38, dune ported, open intake, VF2 reeds. The charts only 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) -
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Thanks for posting up! It's nice to see the differences, power curve wise when its adjusted differently!
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I think Im going to go back and double check where mine are set at!!
Thanks for the info!! -
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Added more details to original post.
Thanks again for all the info and help Jerry! -
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Are you running a 640 main with the UNI? what main did you run with the K&N?
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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. -
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Sweet, that verifies my butt dyno
It's also why I never understood the powervalve removal on drag racers...so what if you're not normally running below 6,000RPM, it makes sense that you'd want any and all available horsepower wherever it's at, right?
So long as it doesn't affect top end where you're normally running, it sure couldn't HURT anything by having a bit more power below the normal RPM range. -
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where did you have it dynoed at?
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READ THE F'N POST!!!!!
j/k At Jerry Hall's shop in AZ. Phoenix AZ. -
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Well, they didn't account for the guys that thought 10 more turns would give them more power...after all, it is a POWERvalve
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The more you wind it the more it rips, right?
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"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 -
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mine works best at 1 1/8 turn
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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.
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Can't wait to see this
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Wasn't the factory setting 4000rpm?
I use to set mine with a quick rpm induction clip on the plug wire. Slowly rev the motor and watch the sight glass on the PV to close. Just lock it down at 4000rpm. Never did count turns. Don't see how any two would be the same. How clean your PV is, how old the spring is, what start point to turn..
Wouldn't the PV setting move with the pipe? So a 5700rpm close wouldn't be best for someone that runs a FMF, PT or non high rpm pipe.
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 -
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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.
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So what is the consensus on this 1 turn?
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..........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. -
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We are on the same page, you just said it way better.
One turn is 5700rpm on his bike, with that oil, at normal temp. It was the best rpm for his setup. Take the same bike and put a FMF or PT pipe on and one turn will not dyno well. In short it's not a good idea just to count turns. Clean the PV window, get a induction tach and set it to close by rpm. As a base, I'd close the PV on low rpm pipes at 4000rpm and high rpm pipes at 5500rpm. Fine tune from that. -
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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.
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Rogue1970's cylinder was a small reed.
The easiest method to find the RPM where the power valve needs to close on the LT250s and LT500s is to make a dyno run with the valve fully open through the whole RPM range and then make a dyno run through the whole RPM range with it fully closed. The point where the two graphs intersect is where the power valve needs to close.
I do not agree with Mat Shearers theory. There is only one optimum closing RPM on the LT power valves. You cannot arbitrarily close it or hold it open to build a smooth power band. If you open or close it too early or too late it will make a distinct zig zag in the power curve. If you close the valve before the intersection point (RPM) on the graph, you loose power from that RPM to the RPM where the two graphs intersect. If you leave the valve open past the intersection RPM of the two graphs, you loose power from the intersection point of the two graphs to the RPM where you finally close the power valve.
The 1st graph shows:
Green line a run with the PV closed the whole run.
Red line a run made with the PV fully open to 7600 RPM.
The two graphs intersect at approximately 5700 RPM.
The 2nd graph shows:
Blue line is the optimum setting where the valve closes at approximately 5700 RPM. -
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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. -
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Jerry, I guessing these test are done with your #19? Maybe I am not seeing things correctly, But looking at the first graph (Green and Red) the Red with P/V open and was making more Bottom end and good Mid and then signs of sharply, Then I think Mat was correct on that he stated more bottom end with more spring tension, But now I understand from your graphs is you need to be in both worlds, have the correct spring tension to take full advantage of the power band of any P/V quad with a performance exhaust, Any chance you could have someone with your guidance take a video to show the correct adjustment to power valve and RPM, maybe bug Dale? Again Thank you for the Info.
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