Husqvarna 162 top end question

[Warped5]

I've got two 162 cylinders here ... one is clearly marked 'A' and the other 'B'.

I've also got one 162 piston here with a single thick ring. It has no obvious markings and is cooking in the USC right now to remove carbon from the crown.

Can't find anything on the interwebs for this ... How do I know which cylinder the piston pairs with?

Thanks!

 

[Mark71gtx]

The ABC's all denote small differences in bore. I am not sure what the preferred clearances are, but I am sure someone here does.

 

[Warped5]

@Tor R perhaps?

 

[Mark71gtx]

@SawTroll or @Mattyo would likely know.

 

[Tor R]

I have no experience with 162, Ted
Not all of my 44 pistons was labeled with A, B, C, D even they all come from the era where those things where super important.

 

[Mattyo]

I think they are different tolerance pistons / cylinders. one is sloppier fit than the other, but I am not an expert on this topic

 

[huskihl]

.0025" to .004" difference in piston to cylinder for oil clearance is a good place to start if the piston isn't marked A or B

 

[Warped5]

In the Mac world, I'm pretty sure that if a piston isn't marked, it's a 'B' ...

 

[Mark71gtx]

Check the fit and ring gap and use the one that you think has the best clearance. Honestly, most people wouldn't have even noticed. It may make a difference in the long run, but I bet either would give good service for quite some time.

 

[jacob j.]

I dry fit the piston to the cylinder (after cleaning everything up) and try to rock the piston back and forth at various points. When confronted with multiple cylinders and pistons of the same model, I just match up pistons and cylinders that seem to have the best fit to one another. That system has worked pretty well.

 

[Motorhead]

I dry fit the piston to the cylinder (after cleaning everything up) and try to rock the piston back and forth at various points. When confronted with multiple cylinders and pistons of the same model, I just match up pistons and cylinders that seem to have the best fit to one another. That system has worked pretty well.

Me too,gotta work with what you've got.

 

[SawTroll]

@SawTroll or @Mattyo would likely know.

This is an old system, that originally was created before plated cylinders were common, so larger cylinders could be used when the bore was worn. However, it carried over to plated cylinders as well - but at that point to cover slight deviances in production, not really wear. The changeover process was gradual though, and the use of the system has diminished as production variances have decreased.

In the 2000s just A, AB and B was used as far as I know, not sure how it is today?

Anyway, it is the piston spring (usually called ring on US forums - but it actually is a spring as well as a ring) that actually rides the bore, so minor size differences between the bore and the piston size aren't that critical - as long as the piston isn't too large.

As I understand it, with a new cylinder the piston should have the same letter as the cylinder, or within one "letter" smaller, and originally you should increase the letter (size) of new pistons as the (iron) bore wore - but it obviously doesn't work that way with plated cylinders, as the bore size doesn't increase much.