Re-Sleeving Stihl Nikasil Cylinders ?

[Timber_Hitch]

I was wondering if anyone had any luck re-sleeving the Nikasil cylinders with cast iron or stainless steel. Wiseco use to sell sleeves and pistons for my CR 500 back in my District 6 racing days. I have a 088 magnum that has a scored cylinder beyond saving, but I cant see paying 450.00 for a new piston cylinder set while I have a complete machine shop at my house. There is allot of hands on experience on this site, I consider this site The United Nations of Chainsaw Knowledge !!!

 

[Sethro]

www.usnicom.com this wisconsin based company is the best.Ken Dunn and myself have had barrels sleeved with great results.

 

[Lakeside53]

A steel sleeve alone without any plating won't last... And to repair it you don't need to resleeve. The nikersil can be bored out, the damage repaired, rebored and then replated/honed.

The economics aren't great though... About $250 for the cylinder rework, $120 for a new piston... gets real close to OEM new.. Don't buy the 084/088 aftermarket piston - it's junk - just an oversized 024 piston with no integral steel heat disk etc.

Talk to your dealer - there's decent margin in the OEM parts, and at this price level he might give you a discount.

 

[olyman]

lake--talk to your dealer????---not the ones close to me--6 within a 40 mile radius--and they all want full retail--ive called them all---

 

[Lakeside53]

Try cash.. sorry...

If anyone calls me on the phone it's full price... (too many price shoppers out there). Come in and talk, maybe things will change.. There is about as much margin in an 088 P&C as selling a 200T... and a lot less work, but everyone has to eat so I can't speak for your dealers.

 

[Timber_Hitch]

Lake I have the cash if you can beat this price, I will have someone pick it up from you Monday.
LOOKS LIKE A SIMPLE RE-PLATE; THE COST IS $170 PLUS SHIPPING
DONT WORRY ABOUT THE STUD, WE WILL TRY TO GET IT OUT FOR YOU IF POSSIBLE; CHECK
OUR WEBSITE WWW.USNICOM.COM FOR ALL PRICES/SHIPPING INSTR.
SCOTT REATH
US CHROME
866-922-5066

 

[Lakeside53]

Sorry. too cheap. Can't buy a cylinder without a piston/rings/pin from Stihl.

Yes, it is cheaper to replate if you don't need repair. Interesting that they can plate with those grooves. What about the piston? How's the taper?

The stud is put in with high temp red loctite. Just use propane and vicegrips, and replace it with a new stud (less then $1)

 

[Timber_Hitch]

Lake, I got a piston Curt Bailey had on Ebay last week. The grooves look deeper than they are, when he chucks it up in the lathe to remove the plating the scratches will dissapear they are only a couple thousandths deep. Lake , it seems like most of the problems with these Stihl saws happen on the exhaust port side of the cylinder maybe there is a better design for this port heat problem. Any Ideas ? I have a complete machine shop at my disposal to try ideas.

 

[Al Smith]

A little word of caution,take it for what it's worth.A piston has taper and ovality,it's not perfectly round.

The portion where the rings are,is in fact round.If however you take accurate micrometer readings in the skirt area you will find there is a slight taper from the bottom of the skirt to the the face,just below the rings.There also is a slight ovality being wider at right angles to the pin placement.

I'm afraid if a person chucked up a piston in a lathe and turned it round,it would in essence just become a paper weight.

This little comment was just meant to be a word of design critera ,what anybody does to their piston is none of my business.

 

[Timber_Hitch]

Al, I was talking about machining the cylinder not the piston. I know pistons are oval shaped at room temperature and are designed to be perfectly round at the saws operating temperature. Thanks for checking with me though, I have learned most of what I know the hard way by screwing things up !!!! :bang:

 

[Al Smith]

With regards to a cylinder liner,I have in fact resleeved a 125 Mac using fine grade gray cast iron.It worked just fine.

I think what has been brought out is that the Nikosil lined engines use an incompatible ring to cast iron,harder or something.

This subject has arisen before,on here and other places on the net.An option perhaps would be to use 4140 steel as is used on aircraft engines.I really have no idea of what the outcome would be.It may or may not work.

If the saw is junk and you have the time and where-with -all,go for it.

 

[Lakeside53]

Lake, I got a piston Curt Bailey had on Ebay last week. The grooves look deeper than they are, when he chucks it up in the lathe to remove the plating the scratches will dissapear they are only a couple thousandths deep. Lake , it seems like most of the problems with these Stihl saws happen on the exhaust port side of the cylinder maybe there is a better design for this port heat problem. Any Ideas ? I have a complete machine shop at my disposal to try ideas.

Problem? The engines last over 2000 hours unless the fuel is bad or they are run lean.. Nothing wrong with the design as it is.

However.. if you are concerned with piston/engine life...
Did you get a genuine Stihl piston?? The 088 runs hot and to stop holes appearing in the top of the piston, there is a steel disk cast into the top (like you see on many Diesel pistons). I wouldn't put an aftermarket piston anywhere near an 084 or 088...

 

[Timber_Hitch]

Lake, here are a couple of pictures of the piston. The intake side looks good and the exhaust side looks like someone painted molten aluminum on it. Lake, when parts are tested and taken to failure many things are learned from these test. If this were a test I was running whether it was bad fuel or a leaned out needle valve the part still failed on the exhaust side. I would not close the patent office yet like Benjamin Franklin wanted to do. If there was a way to keep the piston temperature even on all sides this saw might be able to handle a little more abuse and probably last maybe 3000 hours compared to your 2000. I am just trying to say there is always room for improvement. Six Sigma teaches a way of thinking that doesn't settle even when the product is so called the best in the world.

http://en.wikipedia.org/wiki/Six_Sigma

 

[Lakeside53]

I agree.. but the basic two stroke engine make this pretty much impossible... one side is much hotter than the other by design. If you want to put valves back in the engines, maybe, but so long as the piston is both the inlet and exhaust valve, failures like yours will result.

In any case.. unless there is a fuel or related problem, almost all saw pistons just gracefully "wear out", not melt.

If you can come up with a solution let me know first

 

[RiverRat2]

Al, I was talking about machining the cylinder not the piston. I know pistons are oval shaped at room temperature and are designed to be perfectly round at the saws operating temperature. Thanks for checking with me though, I have learned most of what I know the hard way by screwing things up !!!! :bang:

Timber they did tell you to send the piston you intend on using right ????

That Scott @ US is a first class dude he will fix you up

R2'ed

 

[Timber_Hitch]

River, yes he did say to send the piston. But I am considering getting a OEM because of Lakes concerns about the aftermarket pistons not having the integral steel cast into the pistons ?

 

[rahtreelimbs]

Lake, I got a piston Curt Bailey had on Ebay last week. The grooves look deeper than they are, when he chucks it up in the lathe to remove the plating the scratches will dissapear they are only a couple thousandths deep. Lake , it seems like most of the problems with these Stihl saws happen on the exhaust port side of the cylinder maybe there is a better design for this port heat problem. Any Ideas ? I have a complete machine shop at my disposal to try ideas.

Al, I was talking about machining the cylinder not the piston. I know pistons are oval shaped at room temperature and are designed to be perfectly round at the saws operating temperature. Thanks for checking with me though, I have learned most of what I know the hard way by screwing things up !!!! :bang:

Member of the Blue Man Group ???

 

[Al Smith]

"Blue moon,I saw you standing alone",ah an old belly rubber of the 30's and then the 60's,my time.

So much for that nonsense,now the subject.If you are going to fit a piston to a sleeve,first of all,make sure it is a good one.

Now there are most likely as many opinions of how much clearance as there are grains of sand on the Atlantic sea shore.Being an old iron cylinder McCulloch affectionado,they recommend about 4 and one half thousandths for a 2 and one quarter bore on a saw engine and about 7 on a Kart engine.Remember tight is tight,too tight is siezed.

 

[Lakeside53]

As best I can measure (it's harder then it looks..), when Stihl says 60mm bore, it's 60mm within a handful of 10,000ths... The pistons are undersized appropriately.

The OEM 088 piston has a cast steel disc above the top ring. In addition to heat dissipation, the disc protrudes beyond the piston diameter to assist in blocking the combustion from the top ring. Any bore clearance needs to take this into account. I'd measure a new OEM cylinder and match that..

I'll try to cut one in half tomorrow and post a pic to show the construction.

 

[Al Smith]

A little comment about those composite pistons.It's odd how things go.This was standard practice on heavy industrial engines of so many years ago.

For some unknown reason the practice was pretty much gone by the wayside.My old TO -20 Feurgesons have steel/aluminum pistons.1950 and 1951 respectfully,so there must be something to it,as they have about a zillion hours on them.