Stihl 046/460 big bore kit questions.

[Mad Professor]

Search function here is useless as teats on a bull.

What sizes were they made in? I'm seeing 54 mm. Did they ever make larger?

Who made them and quality?

Trying to sort this out as put some parts on the trading post.

thanks

 

[rupedoggy]

54 is it. If they were much bigger they would be outside the cylinder. How big do you want? You know the bolt circle on the case will only go so big. If you need a bigger bore get a bigger saw.

 

[Mad Professor]

54 is it. If they were much bigger they would be outside the cylinder. How big do you want? You know the bolt circle on the case will only go so big. If you need a bigger bore get a bigger saw.

I'm just checking to see if the cylinders are 52mm and (could still be) are OEM.

If not OEM trying to determine what brand they might be. Hence markings on aftermarket, if not KS or Mahle

 

[drf255]

Most big bores are crap. Besides the general bad quality of most AM P&C’s, the bore increase tends to take up space in the transfer tunnels. Another problem tense to be that the larger piston’s skirt can’t clear the case opening at BDC (which I am 95% certain is the case on an 046), so the AM’s answer is to make the skirt deliberately shorter to clear the case. This causes freeporting and timing issues.

 

[deye223]

Most big bores are crap. Besides the general bad quality of most AM P&C’s, the bore increase tends to take up space in the transfer tunnels. Another problem tense to be that the larger piston’s skirt can’t clear the case opening at BDC (which I am 95% certain is the case on an 046), so the AM’s answer is to make the skirt deliberately shorter to clear the case. This causes freeporting and timing issues.

That and **** port timing .
Cc's not the primary indication of power port numbers are just as important never seen an aftermarket cylinder yet that was worth its weight of material that it was made of .

 

[Mad Professor]

Most big bores are crap. Besides the general bad quality of most AM P&C’s, the bore increase tends to take up space in the transfer tunnels. Another problem tense to be that the larger piston’s skirt can’t clear the case opening at BDC (which I am 95% certain is the case on an 046), so the AM’s answer is to make the skirt deliberately shorter to clear the case. This causes freeporting and timing issues.

That and **** port timing .
Cc's not the primary indication of power port numbers are just as important never seen an aftermarket cylinder yet that was worth its weight of material that it was made of .

I agree most big bore stuff is junk. Just trying to see what is on a couple of saws I'm putting on trading post.

The only aftermarket P/C I've used were Tecomec or Precision Tooling when they were made in Italy and OEM quality. Those weren't big bore kits.