Is a powervalve worth rebuilding?

[glukasil]

hi guys.

kdx250

powervalve is still movable but stiff....
a rod for the valve in the clutch area is snapped.

does it worth doing anything with it ?

should i jam it wide open?
or half way and use 98 gas to prevent detonation?
change sprockets to have more bottom end?

any positive outcome would be appreciated.

thanx a lot.

[fatzx10r]

fix it before your powerband breaks :blink:

[glukasil]

what do you mean by "breaks"?

[steve_t]

He's taking the piss :corn: "Powerband" around here is like those Power Balance bands for athletes

[Jay GTI]

what do you mean by "breaks"?


'tis a long-standing joke round these parts... pretending that the 'powerband' is an actual band that is a replaceable part inside the engine, commonly found in 2 strokes.

[Latte]

'tis a long-standing joke round these parts... pretending that the 'powerband' is an actual band that is a replaceable part inside the engine, commonly found in 2 strokes.

What do you mean, pretending? Just coz you don't have the blue ones....

[Drew]

'tis a long-standing joke round these parts... pretending that the 'powerband' is an actual band that is a replaceable part inside the engine, commonly found in 2 strokes.

Created by an incredible number of people coming into bike shops asking for replacements!

[F5 Dave]

does it worth doing anything with it ?

Come again in Engrish?

KDX & indeed all PVs need maintenance. they will seize up & strip geared parts if they aren't cleaned once & a while. If you want to have decent power through the range then yes it's worth fixing it. If its a hack that you intend to ride till it stops & walk out of the bush as an ecological terrorist then you wouldn't maintain anything. They were an Enduro bike with a performance engine. Just because it is an old bike doesn't mean it has become immune from wearing out now they are no longer competitive.

[glukasil]

how about if it is not economical to rebuild the valve,..............
the bike does not worth that much money and it is not the bike i ride all the time.......
if there is a choice to trash whole bike or de-valve it .........and use it as a spare one or for friends use.......

[F5 Dave]

Does the 'is' button not work on your keyboard?:blink:

I can't remember the 250s PV exactly. The 200 had 2 systems, actually the aircooled one had one as well, but it's been too long. The pre 95s had a circular disc that uncovered a central opening & two geared shutters opening the ex sub ports (& a chamber). The gears would strip & they aren't cheap. Not crazy, just not cheap. May or maynot be avail now.

Many are riding around with valves seized. Dunno just grates me not to have stuff working. At least the early Kawi system didn't drop them into the cylinder.

[Edbear]

What do you mean, pretending? Just coz you don't have the blue ones....

I wanna blue one but they told me they didn't make a powerband for my bike... :crybaby:

I don't know how much power the valves put out though, seems to go okay up to about 170 then it stops going faster... :blink:

[Jay GTI]

What do you mean, pretending? Just coz you don't have the blue ones....

Nah I drive a fore-stroak, I have torks instead of a powerband.


Created by an incredible number of people coming into bike shops asking for replacements!

Not helped by people like we find one here... :psst:

[CRF119]

What is actually broken? The valve will cost nothing to clean it is normaly done at the same time as piston and rings because you can just soak the whole cylinder in cleaner. Is it just that rod broken that pushes the valve up and down? just get it re welded for a box of piss at any engineering shop.

[Edbear]

Nah I drive a fore-stroak, I have torks instead of a powerband.:

Oh, so that's why... :facepalm:

[Taz]

Feckin fix it ya tight arse.

[ellipsis]

...i can get a multi fit tool that makes torks fit in the space where the powerband sits ...i think they were being made under licence in Nepal by Tibetan monks as a bit of a trade off between themselves and them there Maoist types that dont get on well with them...but I dont agree with the yak butter lube system they recommend..

[glukasil]

a mechanic i showed the engine said it needs new one........
even it moves , just stiff.
the broken piece is easily available on ebay.......
dont know who to listen now , the mechanic or you guys :(

[Spearfish]

...i can get a multi fit tool that makes torks fit in the space where the powerband sits ...i think they were being made under licence in Nepal by Tibetan monks as a bit of a trade off between themselves and them there Maoist types that dont get on well with them...but I dont agree with the yak butter lube system they recommend..

They aren't that good though, they are turning up metric torks on imperial lathes.

[glukasil]

the broken piece is part of what is called power valve governor.....

[F5 Dave]

a mechanic i showed the engine said it needs new one........
even it moves , just stiff.
the broken piece is easily available on ebay.......
dont know who to listen now , the mechanic or you guys :(
Depends; what do you want to believe? The governor is a device to change rotational speed into a linear movement using centrifugal force. So what is the rest of the system like in the barrel? Take it apart & clean/inspect it. May as well measure the ring end gap while you are there & check for any other damage. Not looking won't make it any more reliable.

[Edbear]

Depends; what do you want to believe? The governor is a device to change rotational speed into a linear movement using centrifugal force. So what is the rest of the system like in the barrel? Take it apart & clean/inspect it. May as well measure the ring end gap while you are there & check for any other damage. Not looking won't make it any more reliable.

What you don't know... :shutup:

[ellipsis]

...i know nussing about anything to do with mental turks smelling of imperial leather..

[Taz]

the broken piece is easily available on ebay.......


Get it, Strip clean and reassemble power valve assembly (Barrel and head off) Check piston and rings. Reassemble and enjoy. Easy as that.

Oh and you'll need base and head gaskets, may as well just get a top end set and give it a birthday.

Is it a 200 or 250?

[ellipsis]

.....see...easy...

[glukasil]

thanx guys...........
the problem is i have never taken apart engine.........no special tools or knowledge.....

worked a lot with jetski and now bikes but strictly no engines....... i mean when it comes to crankes , pistons , rings , gearboxes

it is why i had to go to mechanic.............

[CRF119]

If you are real tight you could free it up buy removing the expansion chamber and spraying carb clean at the valve assembly. you should also be able to clean the other half from the inspection panel on the side of the barrel.

As for the broken rod that pushes the valve you may still need to remove gear box cover.

Jet skis are much worse then MX bikes. Hoses and shit going every where i have 3 in my shed that are in stages of rebuild

[glukasil]

i have bought the governor from ebay , will have it soon......
will clean the valve with crc/dw40 for sure - it is still moving but stiff.........

actually , how easy it suppose to move if it is ok?

thanx a lot

[ellipsis]

....i feel I must apologise for being a twat,:innocent:... carry on glukasil... welcome to KB...

[Furyos J]

I bought a 2000 cr250 around a year ago, from a guy who said it had heaps of porting work done and it went like a cut cat. I thought it went ok, but nothing spectacular,i got it for a very good price in the end, pulled the barrel off and replaced the piston and rings, and yes it had had porting work done,a mate noticed that the "crows foot" that connects the govener to the powervalve was broken and valve stuck closed (the last owner had the foot in wrong place, and torked the barrel down onto it, breaking it) put new foot in and connected it up properly,pulled power valve down and cleaned with white spirits, what a difference, now it DOES go like a cut cat!!

[CRF119]

The valve should be nearly friction less.