hi all. basically my engine has seized, (09 txt pro 250). iv stripped the top end down and theres damage to the piston and to the barrel, obvously i will need a new piston kit. my problem is the barrel, at what stage is it beyond repair??? if there is just some small scratches can it be repaired and still run a standard piston kit, or will i need a over sized piston, or would it be cheaped jus to get a new barrel, etc etc etc,just need to know my options. am fairly new to this stage of engine work so i appolagise for any questions that may seem abit obvious to you guys. all help appreciated,

many thanks,

will try and upload some pics if that will help

There's a company called Langcourts,they're in the West country[Google it]they will be able to fix it Definetly cheaper than new barrel,give them a call.

'

Hi

a seizure doesnt always = new barrel.

Firstly, Its important to remove any aluminium deposits to reveal the actual plating damage.

Scratches

Clearly if the scratch is deep (can feel a step with your finger nail?) then the games up and it needs to go for replating.

While you can hone Nikasil barrel, this is only relevant for very minor blemishes (Nikasil does streak this is not always terminal).

Very bad scores and more serious damage can be welded and replated.

General wear

Look closely at the top of the bore (where the top ring reaches TDC). Is there a significant step between the worn and unworn areas?

Are there any areas where the plating has worn through (normaly above the exhaust port and near TDC)

Get the bore measured with a bore gauge and compare ovality / taper against the manufacturers spec.

Piston sizes

For most bikes there are 4 sizes of piston for the plated barrel (A,B,C etc)

Often you can fit a larger piston into a slightly worn barrel (check the piston to bore clearance spec for your bike)

Barrel repair

A barrel has to be really bad to make it unrepairable. I've had cracks and gouges welded and repaired.

Try Lancourt cyl replating (UK)

Costs around £130 for a straightforward replate. Its best to send your piston and desired clearance for best results.

Dom

cheers guys, just the sort of replies i was hoping for. many thanks :thumbup:

what made it seize ? will the mains and big end be ok too ?

I had mine done by Splat Shop, send your barrel to them they send it off to Langcourts. When the barrel comes back to them they will select the right size piston and then post it back to you...

Its very easy but you will lose the barrel for about 3 weeks.

You'll not get the best results that way round joeninety. Barrel and piston to Langcourts so they can plate to suit what size the piston actually is, as opposed to what a piston is supposed to be.

The reason i would send it to Langcourts with the piston is they will have much much better bore gauges than your average mechanic. Also this way you can deliberately chose an A or B piston and know that you can go up a size or two in the future. It would be annoying get the barrel back and have to fit a C or D to a new bore.

Where pistons are scarce like classic bikes etc its often cheaper (or there is no alternative) to match the bore to a used piston rather than the other way round.

However, i wouldnt be anal about it. Like me, Chris at Splatshop has probably got a reasonably good bore gauge that's good enough.

Given that many barrels are tapered and / or oval from new (yep!!) you will potentialy also get a better component at the end of this.

Dom

Edited January 26, 201313 yr by dombush

well, i got my barrel back this week. didnt use langcourts in the end, used a company recomended by a bike mechanic friend of mine, and its like a new barrel, really impressed with the job and the turn around time of 15 days. they put it back to an "A" size so the new s3 piston i bought fits like a glove. :thumbup:

Put the bike back together today and seems to be running sweet. obviously still in a bit of a runnin in stage but all seems fine...... and so nice to hear the bike running again after 2 weeks looking at it in bits.......... Only bad bit to this story is iv now discovered a chipped kickstart gear so now need to buy a new one of them aswell. oh well only money i suppose, lol.

will try and get some pics of the bike up over next couple days as shes all clean and back together.

I know i didnt use langcourts in the end but thanks for all the comments and info, was much appreciated.

Also if any of you can point me in the direction of a cheap kickstart gear, that would be great aswell.

cheers