Recovery of a scored cylinder

[t_andersen]

Guys,

I have some scoring under the exhaust port of my Stihl 084. I checked with one of the e-Bay sellers of piston kits whether he would also have an aftermarket cylinder, but he didn't. Instead, he gave me the following advice which makes a lot of sense to me. Anyway, before going ahead, I thought that I would run it by you pros:

"Hi, there is no luck of getting any aftermarket cylinders for 084, the saw is too old. The cylinders I have are plated like originals. They are the same quality. But going back to your 084, you can try cleaning up the cylinder with sandpaper and get the saw run again. Here is how. Piston is made of aluminum, while the cylinder surface is chromed. When the chainsaw scores, the aluminum form piston sticks to the chrome surface. All you need to do is to remove the aluminum with sand paper grinding in spots where you can feel or see aluminum. It is always on the exhaust side. Use thicker paper first to speed up the process and finish with very thin one. Do not scratch the chrome for too long though, scratch only the aluminum.
When you are done, make sure that:
1. YOU CHANGED GAS IN THE TANK, 70% scores is cause by straight gas.
2. Clean the cylinder from all the dust and debris. "

So what's the verdict, does this make sense?

Tom

 

[retoocs555]

Yes it does.

Emmory cloth, works better than paper.

A ball hone works better than emmory cloth.

Try the search for quite a few really informative threads about saving cylinders.

 

[Lakeside53]

I would not use an aftermarket piston in an 084 or 088 (now the same piston). The Stihl piston has a heat dissipation disc make of steel cast into the piston top, and it's needed it particularly for milling... The aftermarket is just an up-sized 024 (for want of a better comparison) piston....


Use a ball hone... Don't use "sandpaper". The advise you got is misleading at best. A little more finesse is called for... If the scorng is just below the exhaust, it will likely clean up enough to give you good results with a new piston. Do you have a photo of the old piston damage?

Did you damage your 084 milling, or is this old damage?

 

[t_andersen]

Cylinder & piston

Andy, here are the photos, sorry they are a bit unsharp. Any comments are welcome. I haven't got around to milling with it yet, too busy with other stuff, so it's not from milling. I have fired it up though.

 

[t_andersen]

Forgot to say that I will buy a ball hone. I suspect that I can't get it from "Hone Depot" :biggrinbounce2:

 

[doc874]

There are some flex-hones on ebay for about $19 usd + shipping, make sure you get the right size for your cylinder. Just type in the word hone and go to additional items or buy-now at bottom of the page. The seller is bracketracer. Good luck.

Doc

 

[trimmmed]

a little gamma correction on the cylinder pics for you

 

[Lakeside53]

It look like it might take a hone and clean up... Seen worse that came to life.. The lines that go up into the combustion zone are more of a problem than those below the exhaust port.

Look carefully at your piston - you can see the edges of the steel disk just above the top ring. After market do not have these. Stihl had it put in put it in to protect the top ring from the combustion flame and to dissipate heat (stops the heat from melting a hole in the crown).

What's the small hole in the cylinder near the top of the bore above the transfer port? Can't remember seeing that before..

 

[Lakeside53]

It look like it might take a hone and clean up... Seen worse that came to life.. The lines that go up into the combustion zone are more of a problem than those below the exhaust port.

Look carefully at your piston - you can see the edges of the steel disk just above the top ring. After market do not have these. Stihl had it put in put it in to protect the top ring from the combustion flame and to dissipate heat (stops the heat from melting a hole in the crown).

What's the small hole in the cylinder near the top of the bore above the transfer port? Can't remember seeing that before..

 

[Lakeside53]

Forgot to say that I will buy a ball hone. I suspect that I can't get it from "Hone Depot" :biggrinbounce2:

 

[xander9727]

Before you go grinding on the cylinder with abrasives take some muratic acid and a cue tip to the aluminum that has transfered. Muratic acid is pool acid and can be had at any pool supply store. The acid will readily eat the aluminum but won't hurt the chrome. If you still have some metal/carbon transfer left you can use a cylinder hone (dingle berry hone) to remove it.

My $.02

 

[Finnbear]

Compression release? Just a guess. Never had my hands on an 084.
Finnbear

What's the small hole in the cylinder near the top of the bore above the transfer port? Can't remember seeing that before..

 

[buck futter]

Before you go grinding on the cylinder with abrasives take some muratic acid and a cue tip to the aluminum that has transfered. Muratic acid is pool acid and can be had at any pool supply store. The acid will readily eat the aluminum but won't hurt the chrome. If you still have some metal/carbon transfer left you can use a cylinder hone (dingle berry hone) to remove it.

My $.02

This is good info but dingle berry hone is destined to become a classic

hahaha, I like it.

Buck