Non original pistons and cylinders

[Tommy Noddy]

What practical difference, if any, is there in fitting non original pistons and cylinders when rebuilding an engine. Is it a case of you get what you pay for or are the original parts just too expensive for what they are? Many thanks

[wyk]

I have spent a lot of time with a few aftermarket cylinders. The worst case scenario is the chrome comes off near the ports due to bad bevels and, well, bad chrome plating; assuming it is chromed and not NiSi.

 

Then there's the ports and the aforementioned bevels. I have only seen bevels as good as OEM on one AM cylinder, and I promptly removed and redid them all due to porting the thing. I will always redo the bevels on any AM before I install them. I have a few buds whom have been bit by them and have lost rings and some top ends due to it.

 

The castings are often a bit crude. I have one where the spark plug isn't a terribly tight fit, but perfectly serviceable nonetheless(and is the strongest saw I own). I had another come in that I spent about 15 minutes with a dremel cleaning up the intake and matching it to the intake boot because it was so off.

 

In my experience, for the money, HyWay does OK, and NWP do OK nowadays. But I still clean those up before installing them.

[wyk]

I forgot to add -

 

I do not trust the circlips or the piston rings that come with AM kits. I always get OEM rings and clips, or at least use Caber brand rings.

[spudulike]

Fully agree with what Wes said - the aftermarket bevels are pretty suspect as are the rings (brittle) and the circlips (soft)!