Chainsaw Repair

How To Basics - Carb Fixes + Mods - IPL and Service Manuals => How To Basics and Fixes => Topic started by: KilliansRedLeo on February 20, 2014, 10:28:47 am

Title: QA on Aftermarket Cylinders
Post by: KilliansRedLeo on February 20, 2014, 10:28:47 am
A buddy of mine and I have built several of the same formula saws. Husqvarna 372 bottom end, Hyway BB 52mm C/P and a Meteor or Stihl 064 piston. We have both noticed that there is a wide variance in what if any base gasket will result in near optimum squish of 0.020.

I just finished one for myself and had to use 0.030 base gasket to get 0.020 squish, where Alan was able to run no base gasket and ended up with a squish of 0.025. The Meteor version of the Stihl 064 piston has a Compression/Pin Center to top of Piston 23mm and Compression/Pin Top to top of Piston 17mm. The standard 372 piston measures Compression/Pin Center to top of Piston 22.5mm and Compression/Pin Top to top of Piston 16.5mm. Hyway does not publish these specs on their BB kit pistons.

However in comparison  the BB kits from Baileys show Compression/Pin Center to top of Piston 22.75mm and Compression/Pin to top of Piston 16.75mm. So this shows that not all AM suppliers go by the same specs or even close.

I have been assuming that Hyway would have copied the stock piston measurements and only increased the bore. So if that is true then we cannot figure out why these things vary so widely. If I were to venture a guess it would be that the cylinders vary in height from deck to squish band outer edge.

Has anyone else seen this or have any thoughts?
Title: Re: QA on Aftermarket Cylinders
Post by: aclarke on February 20, 2014, 11:04:11 am
Is there an actual machine cut squish band on the hyway jug? A lot of the Asian AM jugs I've worked on weren't cut and the chrome is applied irregularly in that area
Title: Re: QA on Aftermarket Cylinders
Post by: KilliansRedLeo on February 20, 2014, 11:09:14 am
IDK, I have some on the way, I will check and post some pics!
Title: Re: QA on Aftermarket Cylinders
Post by: KilliansRedLeo on February 20, 2014, 11:25:26 am
3000FPS also hinted that there may be a deck height difference between a 365SP and a 371/72XP which would also create an issue. I think we will have to wait for SawTroll to chime in before we may know the answer to that. As I do not know how the factory gets this measurement nor do I know the tolerance limits and perhaps Nikko does!
Title: Re: QA on Aftermarket Cylinders
Post by: Cut4fun . on February 21, 2018, 11:37:27 am
Saving ole info

 March 2011 info shared by Gregg that was having them brought into Baileys back in the day.
Meteor cylinders are being cast in Taiwan. Machined and Plated by Gilardoni in Italy, and stuffed with a Meteor piston.
Regards
Gregg