Any idea how much...

[locksmith]

... a KTM 250 exc  "top end" rebuild might be.
Sons 2009 engine half seized. The KTM dealer investigated and declared the top end rebuild needed. They quoted £2000 just for parts but to be fair they said he could get it done a lot cheaper elsewhere.
I know it depends on how many of the parts need replacing but can any mechy types give me a ballpark figure? 

[Kosmic Kartman]

2 Grand for part seems a bit steep. 

Depending on how bad the the scoring on the barrel is, you could hone it or get it rebored if its realy bad. You need to find out what size the last rebore and piston size was then rebore accordingly. If I remember the should piston size should be stamped on the top of the piston. Once you've got your piston and bore size sorted you'll then need to gap your piston rings.

I used to send my 2 stroke bike and go kart barrels to Tabor Karking in Weymouth for rebores. They work to better tolerances than bike shops. Find out your next piston size then send your barrel to them letting them know what size you want the barrel rebored to.

[Captain Haddock]

It's not got a chrome bore has it? That can mean a new barrel rather than hone/rebore if it's scored, still leaves the option of resleeving as long as you can find the right set of rings.

[Kosmic Kartman]

Good point Captian Haddock.

[griff86]

I did a full rebuild on my YZ250 2005 about a year ago.
 
£100 for a new lining in the barrel
£165 for a complete Prox Crank
£100 for Piston kit(includes rings, pin and small end)
£25 for full gasket set
£20 for full seal set
£30 for big end bearings
£20 for coolant.
 
You could easily get it all done for £500 for the parts and thats doing a full rebuild yours might be cheaper depending if you just do a top end rebuild, may aswell do the whole thing on a 2009 model. I replaced everything, save yourself any labour charges and do it your self, 2 strokes are really simple.

[griff86]

I sent my cylinder to these people
http://www.langcourt.com/page27.html
 
Don't buy any Mitaka parts, they are cheap and won't last.

[griff86]

Oh, just checking, are we talking about the 250 exc or 250 exc-f?

[locksmith]

Its a 4 stroke griff.

The dealers have priced just about everything from a new cylinder to valves and springs.
We are asking around locally to find someone to do it, just waiting for a couple of friends to get back to us.
Once someone with experience has a gander I'm hoping they'll say "all you need is so and so" and get the job done.
I'm just trying to get a vague idea of what we might have to pay.

He got it back last night, the top end in bits in a box lol,  I'm definately no expert but a brief look using the car headlights and the cylinder bore had what looked like some heavy staining rather than gouge marks, but we will wait and see.

[griff86]

Ahh see why they quoted so much now.
 
My mate has an RMZ 450 and his full rebuild came to about £800 for parts but he had to replace 2nd&3rd gears and a shift fork, they came to around £300.
I reckon with new valves and a new top end it would be around £500.

[BIG MAC]

A 4 stroke top end seizure is a rare thing ...possible oil pump failure? 'Partial siezure' sounds like something redeemable. Was the bike running ok after it cooled? have you recently changed oil filter (oilways may be obstructed) If it's just witness markings you are seeing I would venture a new set of rings make sure lubrication system is as it should be (not familiar with the engine but pick up clear - strainer clear - oilways clear - new filter...

[locksmith]

He has only just got it. Had been "rebuilt" by the previous owner so we don't know feck all about the engine and it looks like the previous owner knew feck all as well.    Private sale, sold as seen etc etc. If it was local I think I had another way to resolve things so my lad has learnt one of lifes lessons I'm afraid!

[BIG MAC]

You sure it hasnt got a bent valve...take a look at the camshaft and followers

[Sunny Intervals]

Half seized Had me confused 

you saying top end rebuild also had me confused

But you saying that the previous owner rebuild it, not knowing what he was doing has cleared things up for me.

If it's a piston seizure in the barrell, that he hasn't measured and checked correctly, maybe the piston has twisted and sized.
Or he replaced rings, without re boring the barrel, and if  he didn't use a stepped top ring, it could have hit the wear ridge on the top of the stroke, causing the ring to break up and jam down the side of piston. or any number of things that  can cause.

could also be a dropped valve due to broken broken spring etc.
Or crank cam timing out resulting valves hitting piston.
Oil feed problems would usually result in crank seizure first, you get signs like smoke and a lot of heat before this happens.

A seizure is many different things,
until you say what the seizure is, It's going to be hard to say what the cost would be.

[Captain Haddock]

If it's through lack of oil the cam would be first to nip up I'd have thought, the bore will be mostly splash fed, a piston nipping up can be down to not gapping the rings properly although most standard rings are pretty much right as they come out of the packet, still need checking though.
I had an xt600 nip up after about 100 miles from a rebore and wiseco piston job, a quick clean up of the bore and piston and it's still going strong.
Without a close up look it's all guess work.