525 piston rings

As i'm sure a few of you have noticed my bike is in need of a set of piston rings or even a piston!
I  put a new piston in when the main bearings started grumbling about 200 hours ago which i think was a prox piston ( I can't remember now cos I didn't buy the bits myself, Reps got them!) so couple of questions, should i just replace the rings or should i get a whole piston? Will ktm rings fit the prox piston? Any help would be appreciated as i'm just a dumb electrician

I,d check the barrel doesn't need relining first. Other wise its not going to make much difference if the new piston is rattling its way up and down the bore.

steve wrote:I,d check the barrel doesn't need relining first. Other wise its not going to make much difference if the new piston is rattling its way up and down the bore.

Good call Steve, I'd better get it apart first before I buy anything!

At those hours also think strip it down first and have a proper look - including conrod/main bearings, because when I was trying to trade my WR in they all asked when the conrod had been done?
Then price it all up and decide weather best to fix it or flog it
(Just keep quiet about how much work it's done, and how tired it is on any off road bike forums though in case flogging it the best option    )

JTM525 wrote:

steve wrote:I,d check the barrel doesn't need relining first. Other wise its not going to make much difference if the new piston is rattling its way up and down the bore.

Good call Steve, I'd better get it apart first before I buy anything!

I am sure barrel is Nicosyl plated and doesn't  use a liner. This would mean only the one piston size! Order the rings for your piston from Prox...

I have never seen a piston being sold without rings and I have never put a new piston in without rings...

Remove barrel and just check ring gap and piston diameter for wear. I bet they be fine...

If she be a smokin and using oil try replacing the valve guide oil seals. I bet they have gone all hard and burnt and have started falling apart. That's if you can find them at all

But what the f@@k do I know...

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shocker wrote:At those hours also think strip it down first and have a proper look - including conrod/main bearings, because when I was trying to trade my WR in they all asked when the conrod had been done?
Then price it all up and decide weather best to fix it or flog it
(Just keep quiet about how much work it's done, and how tired it is on any off road bike forums though in case flogging it the best option    )

Wash your mouth out! That beast is going nowhere, i'll be buried with it
Once i get my tax bill out the way i'll give her what she needs. Bastard tax man ruins everything!

phil990 wrote:

JTM525 wrote:

steve wrote:I,d check the barrel doesn't need relining first. Other wise its not going to make much difference if the new piston is rattling its way up and down the bore.

Good call Steve, I'd better get it apart first before I buy anything!

I am sure barrel is Nicosyl plated and doesn't  use a liner. This would mean only the one piston size! Order the rings for your piston from Prox...

I have never seen a piston being sold without rings and I have never put a new piston in without rings...

Remove barrel and just check ring gap and piston diameter for wear. I bet they be fine...

If she be a smokin and using oil try replacing the valve guide oil seals. I bet they have gone all hard and burnt and have started falling apart. That's if you can find them at all

But what the f@@k do I know...

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Ay valve guides would be a good place to look, it certainly has no lack of compression, just smokes its tits off! Worse than the rooster so i've been told by those following
I want to do it tidy as i love the bike, i'll contact prox for a price on rings alone but if not i'll just get a piston kit
Cheers Joss

Nicosyl still wears out had it on a kx years ago.
You could also have scores or scuffs that need sorting only way to find out is to get it apart.

On two strokes if I remember right it always seemed to wear away just above exhaust port. Check for wear and tear but on a four stroke you would be unlucky if there was any damage...

If compression is good I would say it will be valve guide seals. If piston is relatively newish just measure piston and rings for any wear...

You will need valve spring compressor, valve grinding past and new valve stem seals. When grinding in valves use just the lightest of touches..

Make sure you check the inlet valves mine were fooked on my 450 just about to go through the valve seat
and you will need to check what size barrel you have on there a no 1 or 2