250 piston powervalve

[Tharrell]

I spotted a 2001 CR250 in apparent good shape with some extra goodies bolted on.
I already have one but my buddy Sam wanted one.
He looked at it and traded a 1996 XR400 even for it.
The guy was asking $1000 and Sam said he only had $700 in the XR.
Pretty good deal huh?
It ran and the guy rode it around. Sam never even cranked it. He's like that, he buys, sells and works on so many bikes. I didn't say anything, he's a big boy right?
After some personal experience on his part, the first things he checked were the radiator fluid and the powervalve indicator on the left side of the cylinder.
He fired it up and ran it some and I was looking to make sure the valve was turning. It wasn't. He started to rev it and I was more concerned with letting it warm up than anything else. The powervalve still didn't move.
Rev a little higher, higher-----bruuuuuuuuup!!!!!
Seized.
Here's the short part of the story.
Someone put the powervalve in and set it down on top of the little crows foot lever and not INTO the center.
That's not the bad part, they put the piston in backwards and the skirt snagged the rod.
When that happened it tilted the piston forward and snaggged the exhaust port. Entertaining huh?
He wasn't pissed at all, he just started laughing!
Anyway, I'm putting a new topend on mine today and we're going to recycle my old stuff to his because he thinks the cylinder is ok.
If not he said he was going to get an Eric Gorr big bore kit.
I'll add some pics later.
btw-He really likes to watch you ballsy hillclimbers. Put more videos out.
After examining the piston and thnking about it, the ring probably caught first and set the rest in motion.
The bike was ridden twice before it seized. It was under very high rpm when it seized.

[seanmx57]

ouch, freakin hacks

[100hp honda]

nothin wrong with doing a topend on the trail

[Speedway73]

Hell....I like the Maico banner in the background!!

[Tharrell]

Used bikes are like a box of chocolates..................

[NightBiker07]

Used bikes are like a box of chocolates..................

yep....i have been fortunate with my last two though!

[Tharrell]

The latest word is the cylinder has a crack in it.
He's gonna drop the sleeve tomorrow.

[Tharrell]

Here's an update for anyone interested.
My buddies cylinder doesn't have a crack. It's a line the ring cut just above the intake ports when it stopped abruptly.
Apparently it's the best damn sleeved cylinder I've ever seen.
My bike is back together except some misc stuff and the damn axle adjusters are froze up. We broke one trying to get it to move.
We're gonna heat it up and try to get it out today.
That's part of todays mission.
The rest is a new tire on the ATK, wash the bottom end of my buddies bike and install the topend. Then we're gonna rip up the neighbors yard.

[100hp honda]

i use antiseize on my axle adjuster bolts. on ktm swingarms its more critical because that end cap is welded into the swingarm, if the bolt gets corroded in and fucks up the threads your in serious trouble. honda isnt so bad because the end cap comes out and can be replaced, still a good idea to use some lube.

[Tharrell]

We got the new back tire on the ATK and it was sitting over there all day daring us to go rip up the neighbors yard but, we had work to do. Still, it was a bitch lookin at it all day.
We tried to slot it really deep but it just didn't work.
There was a stubb left to work with, just enough to weld a nut on.
We drilled small holes in the sides and put some PB Blaster in there and on the ends and let it sit overnight.
Anyway, PB Blaster, heat and some better leverage with a T handle and both came out.
Put some anti seize on them and we're good to go.
Needed to flush debris out of Sams bottom end and the swingarm bolt was stuck bigtime.
More PB Blaster, more heat and this time a bigass hammer and a piece of brass.
Sam hit his hand 4 times with that bigass hammer!
I would have walked away and come back after a few beers but after throwing shit around and a few choice words he kept at it and eventually it came out. The bolt was rusted in the engine case and wouldn't slip through the bushing.
By then it was 5 and we called it a day.
He'll probably have it together tomorrow.

[gregrobo]

you shouldn't use nickel based products on aluminium it causes electrolysis and will corrode and seize up anyway and cause you the same grief

[Tharrell]

The only nickel based product on my bike that I know of is in the cylinder.
The corrosion is between the aluminum swingarm and the steel adjustment bolts, and the steel swingarm bolt and the aluminum engine cases. The rust was really built up on the part that is inside the engine.
The steel rusts and tightens the fit and/or the aluminum oxidizes and that's just as bad.

Sam's bike was rebuilt with my old parts since his really needs to be bored.
I had 135 psi before teardown and he's getting 120 with my old piston/rings.
He's gonna ride it until the 2nd over piston comes in.

The standard main jet is a 420 but his had a 280 in it.
The only thing we could figure is, the squid that put the piston in backwards tried to rejet it to make up for the funky way it was running.
The biggest he had onhand was a 370 and it ran ok.
Mine has a 400 and it runs great.

Anyway, I understand the quest for an aluminum framed 500 now.
This 250 is so forgiving and it really instills confidence.
I was taking turns today that would have made me put a foot down and feather the clutch if it were my steelie 500.
I know the front end is gonna wash on me sometime but it will probably be the absolute worst hardpack turn ever.
This is the absolute best feeling bike I've ever been on, period.
Now a 500AF is on my mind.