power valve missing

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unclefista240

Member

Apr 23, 2007

36

0

• Jul 13, 2007

• #1

rem

 

Last edited: Oct 29, 2008

IndyMX

Crash Test Dummy

~SPONSOR~

Jul 18, 2006

5,548

2

Amo, IN

• Jul 13, 2007

• #2

You should be able to get the parts at bikebandit.com

 

sick 96 250

Damn Yankees

Member

Jul 16, 2004

1,207

0

• Jul 14, 2007

• #3

if you run without the power valve you will have no top end. Did you buy this bike cheap or something recently? Dont just replace the piston and rings without doing the PV.

Just out of curiosity, which O-rings are you speaking of that leak? If your talking about the head then yeah, your bike may fire up for a second then die, your pulling coolant down into the bottom end and cutting out the spark.

Still confused on how you have a bike with the PV missing and never noticed it.

 

S

sixds

Member

Mar 25, 2007

779

0

• Jul 14, 2007

• #4

if you run without the power valve you will have no top end. Did you buy this bike cheap or something recently? Dont just replace the piston and rings without doing the PV.

Click to expand...

i thought the powervalve opened up to make more top end? and when its closed that helps with bottom end, no?

 

sick 96 250

Damn Yankees

Member

Jul 16, 2004

1,207

0

• Jul 14, 2007

• #5

if the power valve is disconnected, when you get into the higher RPM's it will not open to give you the flow you need for the higher RPM's, having no top end.

So no PV, no top end, unless something else crazy is going on

 

S

sixds

Member

Mar 25, 2007

779

0

• Jul 14, 2007

• #6

yes, but he said the powervalve was missing completely, not just not working.

 

IndyMX

Crash Test Dummy

~SPONSOR~

Jul 18, 2006

5,548

2

Amo, IN

• Jul 14, 2007

• #7

if the PV is completely missing, as the OP said, you'll have no bottom at all.. Top end won't be affected.

 

D

dirt bike dave

Sponsoring Member

May 3, 2000

5,348

3

• Jul 14, 2007

• #8

Check to see if the bike has big bore conversion. Not sure about the RM, but a large over bore on some bikes requires removing the PV.

 

J

_JOE_

~SPONSOR~

May 10, 2007

4,697

3

• Jul 14, 2007

• #9

dirt bike dave said:

Check to see if the bike has big bore conversion. Not sure about the RM, but a large over bore on some bikes requires removing the PV.

Click to expand...

My 02 just needed shaved down for a 265(2mm over). I dont see why one would remove it completely.

 

D

dirt bike dave

Sponsoring Member

May 3, 2000

5,348

3

• Jul 14, 2007

• #10

_JOE_ said:

My 02 just needed shaved down for a 265(2mm over). I dont see why one would remove it completely.

Click to expand...

Maybe his is bored to 310. If you needed to shave it to go from 250 to 265, do you think you could go to 310 without removing it? BTW, his '95 also has a different motor than your '02.

I'm just throwing out ideas why someone would remove the powervalve in a dirt bike. Besides accomodating an over bore, the only other thing I can think of is the PV was worn out and busted, and they did want to spend the money to repair properly.

The poster said the 'bike seemed to run OK' even with a worn out top end and no PV. Would it run OK in this condition on a stock bore? Maybe not, but it could with a 310 kit.

 

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unclefista240

Member

Apr 23, 2007

36

0

• Jul 14, 2007

• Thread starter
• #11

yes its completely missing. i havent owned a bike this new nor have i been on a bike in a while so it seemed to run ok to me. does anyone have a head complete with the valve?

 

U

unclefista240

Member

Apr 23, 2007

36

0

• Feb 24, 2008

• Thread starter
• #12

finally done

so i bought powervalves for a 1995 rm 250 (since mine were missing) only to find out that my cylinder was from a 1992. i bought a new piston and waited a few months till i came across a cylinder with powervalves like new,a few hours but in great shape, so i got it all together ,after cleaning measuring and lubing, couldnt get it to start by kicking so i drained the gas put it where it could get warm then pull started it behind my three wheeler. i had to put it in third to get it to turn over. its got the most compression ive ever seen. igot it started but only ran it for a while . when i mixed the gas out in the cold it was like a wad of molasas? thats why i warmed the gas first( heated porch, not blow torch) im gonna do a compression test when shes broke in . form what i could tell its a completely different bike. kansas weather sucks.

 

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mox69

Member

Mar 26, 2007

236

0

• Feb 24, 2008

• #13

Well normal gas won't thicken when its cold out. Even gas mixed with oil should not be noticeably thicker when cold. I would say you have bad gas or oil. I would go pickup brand new gas, and mix in some good 2T oil.

Also, if this thing is freshly rebuilt and put back together correctly it should fire right up. If you have to tow it behind something to get it to start, that indicates there is probably something wrong still. Trying to start it like this will only make the problem worse.

 

B

Blink-182

Member

Feb 2, 2008

127

0

• Feb 24, 2008

• #14

if u left it for a few months with fuel wouldent that mean it would have gotten gunky in the carb?

 

B

BigRedAF

Member

Jan 9, 2005

739

0

• Feb 24, 2008

• #15

sick 96 250 said:

if the power valve is disconnected, when you get into the higher RPM's it will not open to give you the flow you need for the higher RPM's, having no top end.

So no PV, no top end, unless something else crazy is going on

Click to expand...

I think what your saying is improper power valve operation equals less power.

If it stays closed you will have less top end, bottom end will be unaffected.

Completely missing is a mystery. The channels that the valve rides in would cause turbulence and screw a lot of things up.

 

T

tyler_43

Member

Jun 22, 2007

126

0

• Feb 25, 2008

• #16

lol the only time I've ever heard of somebody completely removing the powervalve is when they use the engine in a shifter Kart :P

 

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unclefista240

Member

Apr 23, 2007

36

0

• Feb 26, 2008

• Thread starter
• #17

yeah like i mentioned the power valve was gone completely,and the cylinder was off of a 1992 and my bike and the power valve i purchased are 1995. and yes its all back apart to address the starting issue, its just too damn cold.oh i also found out that it has a hotrod crank so i figure whoever had it before suffered a catastrophic? failure and patched it back together....

 

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tyler_43

Member

Jun 22, 2007

126

0

• Feb 26, 2008

• #18

freaky...

 

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mxcrazed

Member

Mar 1, 2008

23

0

• Mar 1, 2008

• #19

I bought a cylinder for my 89 cr250 it was ported and polished and bored to the largest size wiseco makes with a sleeve and the valves were removed and replaced with these aluminum plugs that were machined to fit the cylinder and port matched and they looked beautiful

also it appeared to have been run on alcohol I think it was out of a shifter cart but no confirmation i was gonna have it resleeved but then i would have to get port work done again maybe i can get by with a hone

 

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tyler_43

Member

Jun 22, 2007

126

0

• Mar 1, 2008

• #20

yes that sure sounds like a kart cylinder... the plugs give it away. That thing will be tuned of sheer top end so I'd advise the port work if you want it in a bike... maybe send it to eric gorr and get him to tune it a lil' more for bottom?