STIHL 028 AV rebuild questions

[MDC]

I have a Stihl 028 AV - shop advised that the piston and likely the cylinder badly scored - muffler off - you can see the score on the piston - it is deep.  I would like to try to rebuild - put new cylinder / piston / rings etc.  How do I know the bore size?  42mm 44mm 46mm?  in order to order the right kit.  Also, where to buy a decent quality kit?  I live in Owen Sound, Ontario Canada.  

[sawguy21]

Welcome! As long as you are buying the piston and cylinder together the bore doesn't matter so go with the largest. Why did it fail? Straight gassed or an air leak? Make sure the bearings, crank seals and intake boot are in good shape so it doesn't happen again.
You are stuck with buying OEM parts from a dealer, Stihl does not sell online. They will be the best quality but also the most expensive. Aftermarket parts are available from U.S. suppliers but the exchange rate and freight make them costly and quality varies.
Welcome!

[MDC]

Thank you for the reply - so from your answer - all 3 sizes of cylinders bolt on to the 028 crankcase - interesting.  The shop did not indicate the cause - the saw would start up (little difficult) and run and rev up and then just die off or rev up and as soon as you put a load on to cut - it would die off.    I had the crank seals replaced a couple of years ago - does not get a lot of use.  Mix of fuel / oil is 40 - 1 using Stihl oil and premium gas.  

I asked the shop what the cause might be - answer they gave was - just old age - it is some 30 plus years old.   They quoted - $400 for the kit - from Stihl.  

There must be some supplier in Canada.  

Thank you again

[ZeroJunk]

The Tecomec kits are OK.  Don't use any cir clip with an ear on it, or snip the ear(s) off.

[MDC]

Thank you for your reply - I am not certain what you mean by CIR CLIP with an ear on it?   I have not dismantled yet - but I expect to find C clips (on the piston - either end of the wrist pin) those usually have a little spot (at the ends - a hole ) to insert the C clip pliers.  Would that be normal or OK?

[ZeroJunk]

You won't find holes in chainsaw wrist pin clips.  Some of the older slower saws had ears where you could squeeze them together to install. They were slow enough for that to work. The newer saws do not come from the factory with ears because metal fatigue will break that little ear off and wreck your saw. Sometimes sooner than later.

You can use OEM clips if the kit comes with the ears. Just make sure that the groove isn't too deep.
There have been some cases where the pin could slip over the clip. You can tell by looking at it.

I have had to rebuild two saws over later because the pin broke. Neither had more than 10 tanks of fuel through them.

[Mad Professor]

The Tecomec kits are OK.  Don't use any cir clip with an ear on it, or snip the ear(s) off.

Tecomec made in Italy, used to be OEM quality.  Now the Chi-Coms make them out of Chinesium.

[Magicman]

I found what you need from FF Sponsor Chainsawr:  LINK  

That is where I got my cylinder/piston from several years ago for my 028 AV rebuild.  

[Mad Professor]

I find what you need from FF Sponsor Chainsawr:  LINK  

That is where I got my cylinder/piston from several years ago for my 028 AV rebuild.  

Good advice from Magicman
Welcome!
Good used OEM cylinder is better than aftermarket.  See if yours will clean up (we can show you how).  Post some pictures.  Clean up the saw before you tear it down.
Might be hard to locate piston if yours is not 46mm "super".  OEM parts from Stihl are starting to dry up, 46mm piston is expensive, no cylinders, and complete gasket set also NLA from stihl. 
Aftermarket parts vary in quality from decent to junk. Meteor makes decent pistons less than 1/2 price of OEM, they list 44mm and 46mm for 028
028 uses the same crank seals as the BR400 blower, and a gasket kit w/seals for BR400 is less  $$$ than buying the 028 seals alone.  Stihl still sells individual gaskets.
You'll want to do the seals and check all the rubber/hoses, then a vac/pressure test when together.
Couple of attachments you'll find useful

[Mad Professor]

Shop manual file is too big to attach here :(

[ZeroJunk]

I think I would jump on that for the price. Probably buy new rings.

[JoshNZ]

It won't take you long to pull the head and measure the piston, quick enough that you should do it before you order. Also lets you check the cylinder which can usually be saved, read up on removing aluminium transfer, that's usually all it is. Acid, or scouring pad. The cylinders are nikasil plated, tough as buggery. I had pretty good luck with both methods with an 038 cylinder however found it was gouged at the end of all my efforts. Look at the transfer through a loupe and you'll know.

That'll also give you a chance to listen to the crank bearings and see if they need doing. Based on what you were saying about over revving I'd be dubious about the seals, they're a pain to test but you can with stuff lying around most workshops if you're creative. Blocking the ports with rubber and wood blocks, and pressurizing the impulse nipple.

I've just done 2 rebuilds, new to chainsaw engines prior to that, and didn't find anything difficult about it. One I went with genuine Stihl the other I went with a meteor kit, pleased with both. Meteor kit looked fine and came with caber rings which are supposed to be great.

Good luck!

[Al_Smith]

Contrary to popular belief things don't have to be perfect to work well .Clean up the cylinder and piston ,throw a set of rings in it and run it .If you don't get stingy with the oil in the gasoline it will run for a long time . It's a chainsaw not a 1927 Rolls Royce .

[ZeroJunk]

Heaven forbid if you run a ball hone in it.  Your piston will literally turn sideways in the bore and kill anybody nearby.

[Mad Professor]

Contrary to popular belief things don't have to be perfect to work well .Clean up the cylinder and piston ,throw a set of rings in it and run it .If you don't get stingy with the oil in the gasoline it will run for a long time . It's a chainsaw not a 1927 Rolls Royce .

Al, shame on you for running a smeared piston!
A meteor piston comes with caber rings and is ~ $35.  Just the rings are going to be $10-15 anyway.
What is your time worth to do things right the first time?

[Mad Professor]

Heaven forbid if you run a ball hone in it.  Your piston will literally turn sideways in the bore and kill anybody nearby.

Ball hones do ugly things to nikasil.

[Al_Smith]

Well professor keep in mind I'm not talking about an MS 250 Stihl or a Poulan Wild Thing  .Try finding a piston for a McCulloch  250 or an Oliver OC 6 crawler circa 1954 .You know some of  us just have to deal with things using different methods . 8)---BTW I have and do use Meteor pistons and Caber rings .CR seals and Permatex #2 -----no Amsoil at 100 to 1---

[ZeroJunk]

Heaven forbid if you run a ball hone in it.  Your piston will literally turn sideways in the bore and kill anybody nearby.

Ball hones do ugly things to nikasil.

Oh, I don't know. I used one the other day on a MS460. I actually timed it out of curiosity just to see how I do it. About 1 1/2 seconds one way and 1 1/2 seconds the other. It will get what little transfer is left on the edge of your ports. And, then in to the dishwasher.
I'm thinking you would really have to dog the heck out of nikasil with a ball hone to hurt it. You are not using it to remove the aluminum. It should already be gone. But, it will slick it up enough that you can see what is left if anything.
Works for me.

[Al_Smith]

FWIW they really don't recommend ball hones on hard nickel ( nikosil ) .If anything the diamond hone stones .
I have a Lisle precision hone hone that has both the diamonds and the regular stones  for cast iron and steel .
The way it works is the silicon carbide element is like a ceramic and a microscopic layer of nickel is above it .The action of the rings removes that layer in a very short time exposing the harder material under it .I can get a link if you want to read it yourself .
I don't hone plating myself ,either hard nickel or chrome .If it needs polished up a tad I use a scotch-brite greenie and kerosene ,no sand paper .Like on any transfer it will come off with some elbow grease .I tried it with a flap wheel and promptly ate right through the plating, bad plan .Live and learn .

[ZeroJunk]

The way I got started in this was when a friend who works for the hardware store brought me two pick up truck loads of Stihl saws, blowers, weedeaters. Customers never picked them up and I guess the repair estimate was too high.
There was an 046 in the bunch so the first thing I did was get a big bore kit for it. Well, the rings broke before you could slip them over the piston. Sent that back and decided I would see if I could clean the cylinder. It was pretty rough.
I had no idea what I was doing and just ordered a ball hone and I cleaned every bit of the aluminum out just with the hone. The plating was missing a little on either side of the ports. Saw ran great.
I gave it to a friend who used it a couple of years for firewood. He gave it to another friend and he called and wanted to know what I had done to that saw, said he had never had a saw that would cut like that.
Anyhow, there is no telling how long I honed on that cylinder. Long enough to know that you can get the plating off. Can't imagine anybody doing it if they are trying not to.

[Al_Smith]

All I'm saying is they don't recommend doing it .What or how anybody does anything really is none of my business .This I will say with a ball or shoe hone you cannot correct ovality or taper .It takes a precision  hone like the Lisle I have .Which I might add was given to me .Dang thing is like a couple hundred for a new one and I'm a tight wad .Chainsaws are only one of my many interests, machining  is another .I'm self taught and can do about anything a tool and die maker can do it just takes me a lot longer .---I also make a lot of mistakes  ;)

[Mad Professor]

Heaven forbid if you run a ball hone in it.  Your piston will literally turn sideways in the bore and kill anybody nearby.

Ball hones do ugly things to nikasil.

Oh, I don't know. I used one the other day on a MS460. I actually timed it out of curiosity just to see how I do it. About 1 1/2 seconds one way and 1 1/2 seconds the other. It will get what little transfer is left on the edge of your ports. And, then in to the dishwasher.
I'm thinking you would really have to dog the heck out of nikasil with a ball hone to hurt it. You are not using it to remove the aluminum. It should already be gone. But, it will slick it up enough that you can see what is left if anything.
Works for me.

UGLY ball hone!

 

 

[Real1shepherd]

Not gonna get into the ball honing controversy, but don't assume a Meteor piston is good quality at a cheap price. They're now linked up with Hyway pistons....so buyer beware.

Your best bet always is to find a good used OE P&C.

There's not enough plating thickness in a chainsaw jug to worry about taper and concentric considerations. If your jug is out of round a lot for some reason, pitch it.

Kevin

[Mad Professor]

Sad if Meteor has gone way of Tecomec?

Tecomec was OEM quality when made in Italy.  Tilton/Total was USA distributor.  Head guy at Tilton said Tecomec went to $#!t- CHI-COM!!!

I spoke with him , Head person, who was distributor for Tecomec for many years.

If Meteor has went Chi-Com , only option is OEM.  I won't but Chi-Com chit.

P.S. I have stash of OEM/NOS Stihl for my saws, nope not for sale?

But I don't buy Brazilian GM Obama cars either

[Real1shepherd]

I can't say for sure....but a close association with Hyway can't be a good thing. Meteor isn't going to bring Hyway quality up, but Hyway is going to bring Meteor down, down, down.......

You get what you pay for in aftermarket chit.....so if Meteor is going for roughly what Hyway is or was.....you get the idea. 

No way I'm stuffing Chinesium in my old warriors.

Kevin