Why would an old saw that still has cross hatching on the cyclinder wall have low compression??
good looking cyclinder but low comp??
- Thread starter 056kid
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Rings that have lost their tension or rings that are stuck in the grooves. How low are you talking about?
Check your ring end gap, should be no more than .012 thous.
End gap or stuck rings. The rings could be stuck due to caramelized/crystallized fuel due to sitting a long time.
You did not say which saw this was but back in the 056 day saws were fitted with individual pistons. The top of the cylinder (outside) was marked with a letter. A was the tightest and E was biggest. The piston was matched with the bore. The latest pistons are just marked a/b and are kind of a "fits all" fix. You may have a wrong piston/cylinder match or your piston may be excessively worn (in addition to rings).
The pistons are responsible for most of the compression in a two stroke. That is why I never hone a cylinder. The company manuals don't want you to either. My pleas fall on deaf ears because so many feel honing is a good idea.
The 056 saws seem more prone to this problem than others for some reason. I have had some saws run OK at 110# compression but the 056 seems to need at least 130# or more. Doesn't make sense but that is the way it is. BTW when an 056 runs good it is a good and powerful saw. Mike
The pistons are responsible for most of the compression in a two stroke. That is why I never hone a cylinder. The company manuals don't want you to either. My pleas fall on deaf ears because so many feel honing is a good idea.
The 056 saws seem more prone to this problem than others for some reason. I have had some saws run OK at 110# compression but the 056 seems to need at least 130# or more. Doesn't make sense but that is the way it is. BTW when an 056 runs good it is a good and powerful saw. Mike
SO, how do you get the rings to seat with out honing??????:monkey:
William Balaska
Addicted to ArboristSite
New rings will still seat without honing
Thank you William. You have a nice smooth cylinder wall. Why do you want to scratch it up? Mike
Cameljoe73
ArboristSite Operative
ok
tdi-rick
Addicted to ArboristSite
If an engine uses Nikasil or similar electroplating, you don't hone them.
Also, may mechanics use a ball hone on cylinders before reassembling during a top-end rebuild. Ball hones are used to create fine oil retention paths on cast iron cylinders. On Nikasil cylinders, however, a ball hone won't do this. Instead, a ball hone will knock the Silicon Carbide peaks from the coating which wrecks the surface's oil retention capability. Ball hones are a bad idea for use on Nikasil coatings.
http://www.electrosil.com.au/news1.htm
Also, may mechanics use a ball hone on cylinders before reassembling during a top-end rebuild. Ball hones are used to create fine oil retention paths on cast iron cylinders. On Nikasil cylinders, however, a ball hone won't do this. Instead, a ball hone will knock the Silicon Carbide peaks from the coating which wrecks the surface's oil retention capability. Ball hones are a bad idea for use on Nikasil coatings.
http://www.electrosil.com.au/news1.htm
Lakeside53
Stihl Wrenching
Even nikersil/chrome cylinders are honed when made. It's done with a diamond hone to set size. Check out a new cylinder sometime. The hone "cross-hatch" (not for oil retention as on cast iron) can usually be seen even on lower parts of an old cylinder if the piston has an open skirt.
I've honed tons of crappy cylinders with 320 grit silicon carbide ball hones... However... unless it "needs" cleaning up, there is no need to hone at. Rings will seat in a few tanks no matter what your do, or don't.
I've honed tons of crappy cylinders with 320 grit silicon carbide ball hones... However... unless it "needs" cleaning up, there is no need to hone at. Rings will seat in a few tanks no matter what your do, or don't.
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tdi-rick
Addicted to ArboristSite
yeah, but the point is Nikasil bores aren't honed with a 'standard' ball hone, and that the average bloke in his workshop shouldn't just run a ball hone through it "so the rings will seat".
Plateau honing is mentioned in the link above.
They are impregnated nylon brushes that don't remove any extra material from the measured bore, but clean out any debris and folded over material in the valleys, significantly decreasing irregularities in the bore finish.
