Husqvarna 254xp no compression but cylinder not scored

[Jonny Vee]

I had sitting on the shed an old Husqvarna 254xp for long long time. By memory stopped working and we parked there.

Before taking apart I checked compression and was 50psi. Decompression valve seems to close fine. Piston not scored through exhaust I the removed the head.

I can't see any score on the cylinder and piston.

Shall I still replace piston and ring?

Could be ring worn which make it lose compression?

 

[Burnerman]

Certainly you need to expose the piston completely just to see that the ring(s) are intact, and the piston isn't scored in a place you can't see. (Unless you've already done that - barrel off).
Decompressors are generally reliable but wire brush the carbon away at the same time.
For what they cost, I'd shove in a new piston and ring anyway.
I assume the cylinder liner coating - usually Nikasil - hasn't been deglazed by someone in the past?
John

 

[Jonny Vee]

The Cylinder seems to be a Mahle. Not sure if this is an oem or already replaced in the past. Attached photos on how look like.

If good I would rather keep a brand product instead of going Chinese.

 

[Burnerman]

The barrel looks absolutely perfect, is the piston the same?
I’d stick with Husqvarna, brilliant machines and the replacement pistons and barrels I’ve used in the past have been great.
GHS Ltd and L&S Engineers are good suppliers.
John

 

[Jonny Vee]

Here you piston photos

GhS got comet piston. Oem parts are very expensive

What do you think?

Piston seems okay unless they worn out

 

[Harry Bloomfield]

I would investigate the valve. Pour a dribble of oil down the plug hole, and if that doesn't help the compression, it's the valve passing.

 

[Burnerman]

That piston isn't as good as I'd like to see - it's a bit matt on the thrust faces. Ideally there shouldn't be any real abrasion there.
I'd go for the GHS piston, genuine ones are horrific in price....it will come with a ring, gudgeon pin and circlips - please use all of the bits!
John

 

[Jonny Vee]

I would investigate the valve. Pour a dribble of oil down the plug hole, and if that doesn't help the compression, it's the valve passing.

You mean the decompression valve?

 

[Jonny Vee]

That piston isn't as good as I'd like to see - it's a bit matt on the thrust faces. Ideally there shouldn't be any real abrasion there.
I'd go for the GHS piston, genuine ones are horrific in price....it will come with a ring, gudgeon pin and circlips - please use all of the bits!
John

Yeah I will get one from GHS. Are Meter piston good enough?

 

[Burnerman]

I've used them before with no issues....GHS often supply War-Tec which is also good.
John
P.S Harry will mean the decompressor valve.
J.

 

[Harry Bloomfield]

You mean the decompression valve?

Yes, that would be my main suspect and a cheaper fix if passing.