Stihl cylinder/piston kits. Genuine or non-genuine?

[Charles Ekin]

Greetings

I need to change the cylinder and piston on my Stihl FS400 strimmer. (There was no specific forum for strimmers, so I thought this was the best place out of the other options). Genuine part £160+vat, non-genuine part on e-bay or elsewhere around the £40 mark. Any ideas about what to look out for, tips, strong opinions, etc very welcome. All I've been told so far is that the same casting moulds that make the parts for Stihl will be used for other brands unless they are Chinese, and in which case, they make their own moulds which are more likely to be dodgy. Any thoughts?

Thanks

Charlie

[spudulike]

Greetings

I need to change the cylinder and piston on my Stihl FS400 strimmer. (There was no specific forum for strimmers, so I thought this was the best place out of the other options). Genuine part £160+vat, non-genuine part on e-bay or elsewhere around the £40 mark. Any ideas about what to look out for, tips, strong opinions, etc very welcome. All I've been told so far is that the same casting moulds that make the parts for Stihl will be used for other brands unless they are Chinese, and in which case, they make their own moulds which are more likely to be dodgy. Any thoughts?

Thanks

Charlie

 

I can't believe Stihl would let third parties, Chinese or other use their moulds?????

Typical issues of aftermarket kits are brittle rings, dodgy circlips and poor piston fit!

[Ray1]

Why do you need to change it, is it beyond repair? I would rather fit a second hand original top end on it than a copy. It shares the same piston as a 023 or 025 chainsaw, cant remember which one without looking at the books.

[spudulike]

The cylinder lining /plating very rarely wears out - only seen a couple that have gone and mostly due to inress of crap through the air filter.

 

If it has seized, then as Ray suggests, fit a new piston and salvage the cylinder. It is very rare where one gets scored that bad it cant be cleaned up with the usual methods.

[SawTroll]

I can't believe Stihl would let third parties, Chinese or other use their moulds?????

Typical issues of aftermarket kits are brittle rings, dodgy circlips and poor piston fit!

Poor casting and sloppy chamfering around ports as well. Mostly the porting itself is less effective than OEM as well.

 

Some aftermarkets top ends will be OK if you just want the mashine to run again, but don't expect it to run as well as an OEM top end would.

[Charles Ekin]

Thanks for your replies.

I bought the machine on e-bay. I could not bring the revs down by adjusting the high speed jet. (I later discovered the tamper proof plastic attachment on the screw put there because of Californian anti-pollution laws). Used it for too long probably on high revs, which may have happened before I bought it also. Power was low. Decided to take the cylinder off and have a look inside. Both piston and cylinder are scoured.

 

Does anyone know if I can get the cylinder machined and therefore just go with the expense of an original Stihl piston, rather than both?

 

Many thanks

Charlie

[Charles Ekin]

Thanks Spud.

When you say, "It is very rare where one gets scored that bad it cant be cleaned up with the usual methods", what methods would you use to restore a scoured cylinder?

Thanks

Charlie

[spudulike]

Thanks Spud.

When you say, "It is very rare where one gets scored that bad it cant be cleaned up with the usual methods", what methods would you use to restore a scoured cylinder?

Thanks

Charlie

 

Acid or alkali on the aluminium transfer to remove it, abrasive paper to remove the oxide residue and possibly a hone lightly used to finish.

[Charles Ekin]

Spud

Thanks for the details about restoring the cylinder. This is beyond my level of expertise. Do you know of anyone who might be able to do this work for me (paid of course!)

Many thanks

Charlie

[spudulike]

Whereabouts in the country are you? Options include dropping the whole machine off to one of the techs on here that may be able to work on it or just sending in the cylinder my way and I will clear the ally transfer, clean and lightly hone the cylinder.

 

If it is salvageable, I will charge a reasonable rate, if it is scrap, I will charge just the return fee!

 

You would need to make sure you check all the things that may have caused the issue in the first place on refitting though if I just clean the bore!