250r power valve

[badchevelleman66]

lets see if any of you can help me start a new project......

is it possible to power valve an 250R bottom end, ie just bolting on a power valve head

would it be cheaper less hasle to just bolt in a powervalved motor and change the kicker???



what would make this swap difficult. i know its not just bolting on a new head so what else is there.

thanks guys
eRiC

[Red Rider]

It can be done, but it's not easy by any means. On my website, I have pictures of most of the mods that I did to my clutch side cover, as well as a basic rundown of the mods necessary to make it a reality. The motor swap would probably be easier, good luck with reversing the kickstarter though.

[84KXTtecate]

Or you could buy the kit from ESR and save some time and hassle.

[deathman53]

I bought one of these, cost me a good bit, but it has way more power than I ever expected.

http://pictureposter.allbrand.nu/pictures/deathman53/310pv.JPG.html

[NOS_350X]

I got that 91 cr engine that i can make a deal with you for.

[Breastman569]

do all 88-91 CR250'S have pv's in them? if so why not just do an engine swap?

[Red Rider]

do all 88-91 CR250'S have pv's in them? if so why not just do an engine swap?Yes they do. There were 5 reasons:
1. I didn't have a CR250 engine & they're usually kind of pricey when you can find one.
2. CR250's aren't counterbalanced & I was worried about the vibration (I had ridden 86-87 Tecates before).
3. CR250's only have a 5 speed & I didn't want to lose my 6 speed gearbox.
4. CR250's kickstart backwards & I didn't want to modify my rear fenders to accomodate that.
5. CR250's don't have a lighting coil & I wanted to have the lighting option.

[disco]

What's the benefit to the powervalve? Is it the same kind of deal as a Holley Carb?

[Breastman569]

Yes they do. There were 5 reasons:
1. I didn't have a CR250 engine & they're usually kind of pricey when you can find one.
2. CR250's aren't counterbalanced & I was worried about the vibration (I had ridden 86-87 Tecates before).
3. CR250's only have a 5 speed & I didn't want to lose my 6 speed gearbox.
4. CR250's kickstart backwards & I didn't want to modify my rear fenders to accomodate that.
5. CR250's don't have a lighting coil & I wanted to have the lighting option.

wow thanks for the info this is somthing that im not very educated on and would like to learn a lot more about, but thanks again.

[NOS_350X]

What's the benefit to the powervalve? Is it the same kind of deal as a Holley Carb?

No, Its 2 little things in the exhaust port that open and close depending on your rpm's. It perty much gives a 2 stroke bottom end.

[deathman53]

typically for pv motors they do a drag type port to make max horsepower, but they use the pv so it makes low end, mid range and top end, without a huge snap.

[disco]

Other than the $1K ESR kit, does anyone else make one? Seems like it would be cool, but a grand is a bit much to handle.

[ridetrikes250R]

you wont find a cheap powervalve maker, they all are about 1k-1500 bucks.. but i can tell you that they frikin rip! i think you can find a 265PV for around 850 if you deal with a dealer and agree to some terms (wereing stickers on a truck passing out cards stuff like that) alot of guys will negotiate with you if you have cash... i personally put in for a 310,330, and a 265PV from a freind who is a dealer, he needed all 3 for the shelves but i get first pick of what i want... i was able to get him around my budget... most guys will do this.... anyways.. i ahve dealt with regular big bores and they are a blast... a PV just makes your ripp off the bottom like a 4stroke and rev like atwostroke.. i defently love PV's but i could be perfectly fine with a well built 310 or 330 cylinder.
adam

[Dammit!]

I've been wanting a PV top end for ages. Always wondered how the aftermarket ones work though. Factory PV setups have some sort of governor or gear that operates them that's located in the bottom end but the aftermarket solutions do not.

http://webserver1.dancris.com/~dammit/pv.jpg

I assume that's a vaccum line running off it? Where does it go? Somebody shed some light on this for me. :)

[ridetrikes250R]

if you look... the actaul valve assembly is somewhat on the outside of the cylinder. it sorta works like a BOV with a turbo, a spring on the aftermarket one spings shut under low pressure (bottom end on a twostroke) then as pressure builds it slowly opens till theres so much pressure its fully open.... thats the red assembly ont he exhaust side of the cylinder.
adam

[Red Rider]

I've been wanting a PV top end for ages. Always wondered how the aftermarket ones work though. I assume that's a vaccum line running off it? Where does it go? Somebody shed some light on this for me. :)I think you're right Dammit! I also assume that's a vaccum line. I would also assume that it runs over to the right side of the cylinder somewhere, similar to the Tri-Z's fuel pump setup. I know there's got to be somebody on here with a Pro-X PV cylinder that can settle this once & for all. How about you Deathman53? How does it function? Inquiring minds want to know.

[deathman53]

the cylinder I have is aftermarket, it works off of vacum pressure inside of the cylnder, there is no vacum lines or anything. It is almsot the same as a rotax powervalve, or better known as a rotax r.a.v.e cylinder. lrd, ct, cuncan use the rotax style, esr uses the other type, both cylinder are made by pro-x.

[Dammit!]

I've heard you have to clean out the powervalve assembly often (on CR250's anyway). Any truth to that with the aftermarket stuff?

I'm going to be refinancing my house in the next few months. I might treat myself to a new top end when I do. :demon:

[deathman53]

you don't need to clean it alot, the most important thing you can get put a pre-filter on the outside of it to keep crap out of it.

[Dammit!]

I don't suppose you or anyone has a link to a site that has an in-depth explanation of how these things work do you? I understand the principle but something with good pics and diagrams would be cool to see. Until your last post I had no idea it needed a filter. :chuckle:

[Red Rider]

I've heard you have to clean out the powervalve assembly often (on CR250's anyway).I took my pipe off the other day to install a billet exhaust flange, and while it's off I thought I'd pull all the PV covers & check for sticking valves due to carbon buildup. I'll let you know what I find when I do it. I've been kind of busy with other things, what with Christmas only a few days away and all. :D

[Mr. Sandman]

I've been wanting a PV top end for ages. Always wondered how the aftermarket ones work though. Factory PV setups have some sort of governor or gear that operates them that's located in the bottom end but the aftermarket solutions do not.

http://webserver1.dancris.com/~dammit/pv.jpg

I assume that's a vaccum line running off it? Where does it go? Somebody shed some light on this for me. :)

I may be wrong, but I don't think that ESR PV cylinder will fit on an ATC 250R due to lack of clearance between it and the down tube(s) of the frame. My non-PV ESR 310 cylinder and head fit extremely tight. The coolant hose was a bitch to get on and the spark plug is almost impossible to get to because of the thickness of the head and the lack of an angled spark plug hole like the stock head has. This set up will fit a Fourtrax with no problems, but you better confirm with ESR that it can be bolted on to a three wheeler before plunking down your $$$.

[deathman53]

my lrd works perfect in the atc, make sure you specifiy to them its going into a atc!!!!

[bigyellow4x4]

do the esr kits fit in to the 3 wheels with outthat pv assmbly hitting anything i herd some kit have clearance problems? need more light thanks

[ridetrikes250R]

esr 310-330 kits will fit fine.. even witht he power valve... its 350-up they start to hit...
adam