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Author Topic: Power valve delete  (Read 1614 times)

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Power valve delete
« on: August 10, 2013, 09:26:34 pm »
What all is involved in deleting the power valve on an LT that will be used for hill shooting? Is this something that can be done with common hand tools?

I'm just trying to help out another zilla rider.
Brian
1988 Suzuki LT-250R (The HPR test mule)
1987 Suzuki LT-500R
1990 Suzuki LT-500R
1982 Honda ATC-185S
1982 Honda ATC-250R

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Re: Power valve delete
« Reply #1 on: August 11, 2013, 01:00:27 am »
Im involved when the PW dosnt work !
you mean you want to turn off the Power Valve or make ineffective?
To drive only uphills ? 
To race uphills .......     you need a big midrange power!
Spend a little time to rebuild the PW ......and you have a better uphillshooter! O0
under-steers is when you see the tree the goes in. overrides is when you hear the tree which you were going on.
"Walther Röhrl "

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Re: Power valve delete
« Reply #2 on: August 11, 2013, 05:38:35 am »
You will need it coming DOWN the hill. Lower RPM.  :))

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Re: Power valve delete
« Reply #3 on: August 11, 2013, 07:46:58 am »
Diableo,
I think JH, bends the arm/tab coming off the PV, the one you see in the window, so that the PV is stuck with the closed.

I believe you have to disconnect the arm and most likely remove it also but I'd check with him.


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Re: Power valve delete
« Reply #4 on: August 11, 2013, 09:01:31 am »
Diableo,
I think JH, bends the arm/tab coming off the PV, the one you see in the window, so that the PV is stuck with the closed.

I believe you have to disconnect the arm and most likely remove it also but I'd check with him.

Exactly what I was told, but was to chicken sh*t to try it yet
87 HPR LT500
04 Roll LOBO II TRX250R
06 LTR450
87 LT500
85 & 86 LT250
86 & 87 TRX250R
07 & 09 Husqvarna TE450
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Re: Power valve delete
« Reply #5 on: August 11, 2013, 09:32:44 am »
Could try sbl designs power valve block off kit
91 Lt250r Bartlett port and head mod v force 2 Hinson Clutch Basket Cool Head Scp Pipe and silencer ,KN air filter ,EBC clutch, Ohlins  Triple rate Shocks Redone by PEP Shocks,Stock Rear Shock Redone By Pep Shock,  DG nerf Bars , Lonestar axle 2+2,Lonestar Swingarm ,Douglas Red Label rims.

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Re: Power valve delete
« Reply #6 on: August 11, 2013, 09:42:39 am »
I will give Jerry a jingle & see what he says.

Bret, I'm working on the other 500 that showed up at glamis with me last march, the one that blew the head gasket. He wants to turn it in to a hill monster. He has a ported & reinforced 87 jug for it now and will be using the CT outlaw pipe. Hopefully it will be ready for dune season for him.
Brian
1988 Suzuki LT-250R (The HPR test mule)
1987 Suzuki LT-500R
1990 Suzuki LT-500R
1982 Honda ATC-185S
1982 Honda ATC-250R

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Re: Power valve delete
« Reply #7 on: August 11, 2013, 01:19:58 pm »
frank: need more hi rpm power!

that is el diablo on the i zilla
1985 Yamaha Tri Z 250
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Re: Power valve delete
« Reply #8 on: August 12, 2013, 12:25:40 am »
Blocking off the PV will give you a grand total of zero extra HP.
It closes right about the time the pipe kicks in, so it's basically blocked off any time your RPM is up there, and permanently blocking it off is redundant.
What it will do, however, is cause a loss of power in low-mid range.
That being said, why would you get rid of essentially free power, regardless of how you ride?
Rogue1970's dyno runs gave proof that the engine produces power better with a properly tuned PV.
With that in mind, do you think any type of racer would willingly give up power without getting anything beneficial from it?
Even in a pure drag or hillshooting scenario, the PV is going to get you on the pipe just a tiny bit faster, and in the world of racing those tiny little bits are what add up to winning races.

If the guy is having trouble with the PV or it isn't working right, it's better to fix the PV rather than block it off.
That being said, remove the spring on the PV, stuff something solid in place of the spring, make sure it's CLOSED, then tighten the cover down on it.
That'll hold the barrel in place, and the arm can be left attached.
The actuator is only forced back by spring pressure, so it's fine if it stays connected and won't harm anything internally.

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Re: Power valve delete
« Reply #9 on: August 12, 2013, 01:49:20 am »
Im not saying the motor will make more hp
Imo the 500 makes good tq just by being a 500.deleting the pv would just simplify the motor and it would just be one less part that could go out of adjustment. Up to the end user to decide.
1985 Yamaha Tri Z 250
2006 Suzuki LTR 450
2011 Suzuki Hayabusa

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Re: Power valve delete
« Reply #10 on: August 12, 2013, 05:03:26 am »
A functioning power valve is way better than not having one. 

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Re: Power valve delete
« Reply #11 on: August 12, 2013, 11:41:34 am »
NO!!!!!!!!!!!!!!You cannot get more low end by keeping the valve open longer.Closing the valve too late will cause power to dip at the higher RPM and can lead to destructive detonation.There is one correct spring tension setting for your porting and pipe combination that will give you the best overall power everywhere if the system consistently repeats the engagement RPM. 
Quote"  Jerry Hall  " !
under-steers is when you see the tree the goes in. overrides is when you hear the tree which you were going on.
"Walther Röhrl "

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Re: Power valve delete
« Reply #12 on: August 12, 2013, 12:06:21 pm »
Power valves are designed to optimize low end performance up to about the 4,000 rpm range. Since most hillshooter & drag bikes are launched at a high rpm anyways, the power valve would be ineffective right from the start. Especially when you shift at 7,500 + rpm. Your rpm drop might be down into the 5,000 rpm range if you are short shifting.

Mr Hall would be better to provide the specifics.
Brian
1988 Suzuki LT-250R (The HPR test mule)
1987 Suzuki LT-500R
1990 Suzuki LT-500R
1982 Honda ATC-185S
1982 Honda ATC-250R

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Re: Power valve delete
« Reply #13 on: August 12, 2013, 12:15:40 pm »
When was the last time u short shifted anything Brian
1985 Yamaha Tri Z 250
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Re: Power valve delete
« Reply #14 on: August 12, 2013, 12:51:13 pm »
Aaaahahahahahahhahaa!!!

 

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