# Could I fix my Stihl MS 250?



## donmattingly (Dec 7, 2011)

I won't start. Took it to the shop and the guy says the piston and cylinder are "junk" and it is not worth fixing after paying for the parts and about 3 hours of labor. Question is, could I replace the piston and cylinder? Is this the most difficult thing in the world to do? I see the the parts are available via ebay. I have been known to tinker from time to time but I was wondering if there are people on this forum who could tell me if $60 and over 3 hours of my time is worth it. 
Thanks!


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## babzog (Dec 7, 2011)

I've ordered the parts (p&c) to fix an ms290 sitting in a box in my garage. $80 and however long it will take me. My time is free so I'm only out the parts cost. Ir'll be a learning experience for sure since I've never rebuilt anything bigger than a model airplane engine before.


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## Blasket (Dec 7, 2011)

I rebuilt my FarmBoss 290 with new piston/cyl from Ebay after my brother in law ran it with straight gas.  On a 1 to 10 scale for some one who is handy and likes to tinker, I would put it at a 5.  It is a great learning experience, and will give you a world of knowledge on chainsaws.  However, before you go off buying parts for your saw you need to find out what destroyed your first piston & cylinder, good luck!


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## thinkxingu (Dec 7, 2011)

If you've got the time, a warm place to work on it, and you like the saw, go for it.  It's fun to play and the risk is minimal.

S


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## Freeheat (Dec 7, 2011)

There isn't to much to a 2 cycle engine( so to speak)  no valves or head gaskets. I would dive into it . I myself am a big job guy and stink at tuning. If it were me put the cylinder on and have the shop fine tune it. The other great news is there is so much knowledge on this site that if you get stuck ask some questions .


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## donmattingly (Dec 7, 2011)

Thank you for all the responses. The gentleman at the shop said it was most likely bad/old gas that killed the piston and cylinder which I believe. I remember the last time I used it after the October snowstorm, I just used the mix that could have been a couple of months old. The guy also said with all the crap they put in gasoline these days, it has a shelf life of about 14 days. I will be more vigilant now.


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## mayhem (Dec 7, 2011)

I've never done it myself but I'm itching to try, just have to find the right dead saw.  I think its a relatively simple procedure overall and while it mght take us twice as long as the guy in saw shop, I thin kits time well spend.

Since its dead anyway you have nothing to lose, so disassemble the saw and get the cylinder off the piston and get some good sharp photos of the damamge.  If its not too bad you mgiht be able to clean up the cylinder with muriatic acid and only replace the piston and rings, whcih will knock the parts cost down considerably.

Take a look at the damamge and see where its ruined.  Intake side damamge is debris getting in past the filter or in the gas, exhaust side damamge is too lean, or stragiht gas damage or an air leak (which causes a to lean condition).

If you opt to not fix it let me know what you want for it, maybe we can work something out.  I've never owned a Stihl and it could be a fun winter project.


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## smokinj (Dec 7, 2011)

thinkxingu said:
			
		

> If you've got the time, a warm place to work on it, and you like the saw, go for it.  It's fun to play and the risk is minimal.
> 
> S



Warm place is key!  :cheese:


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## Danno77 (Dec 7, 2011)

I can't tell you what your time is worth.

if you got tools and time, then I say "do it".

Get a good workspace and take the entire thing apart, if you decide that it was just too complicated to do that, then don't buy the new P&C and pack the parts in a box and sell them on ebay (or send me or Mayhem a PM) and you are no worse off then you are right now.

If you decide it wasn't as bad as you thought, then we'll direct you to replacement parts and help you any way we can over the interweb while you reassemble it!

let me know if you need a service manual and parts list. i think I have them somewhere  on this computer (dad has a MS250)


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## Danno77 (Dec 7, 2011)

this doesn't look so bad, does it?






BTW, that leads me to a cool thing I've been doing on my saw projects. If you go to the mailing supplies isle of your local store, then you'll find a big roll of brown paper for like 10-15 bucks (it's been a year since I bought it). it is a perfect fit for my work table and you can spread parts all over and draw circles around them and make labels and write notes, etc etc. It's awesome. Then when you are done with it, you rip it off the roll and throw it away. pretty much works like that white paper doctors use on their examination tables. If nothing else it keeps your table from being ruined with oil and gas (the paper absorbs most, but not all of those things, so still be careful)


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## oldspark (Dec 7, 2011)

donmattingly said:
			
		

> . The guy also said with all the crap they put in gasoline these days, it has a shelf life of about 14 days. I will be more vigilant now.


 What ever.


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## smokinj (Dec 7, 2011)

Danno77 said:
			
		

> this doesn't look so bad, does it?
> 
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Perfect, now keep everyone far away!  :lol:


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## Danno77 (Dec 9, 2011)

so, what did you decide? gonna try it or not?


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## smokinj (Dec 9, 2011)

Danno77 said:
			
		

> so, what did you decide? gonna try it or not?



Looks like a piece of the case and fuel tank. Only seeing four screw I think there should be more of those as-well.


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## Danno77 (Dec 9, 2011)

smokinjay said:
			
		

> Danno77 said:
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> ...


not you, ya dork! I was wondering if Don was gonna try to fix his 250!

I asked Pen to split our fun game off of this thread, but he couldn't. I'll start a new one so I can stump you!


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## smokinj (Dec 9, 2011)

Danno77 said:
			
		

> smokinjay said:
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lol, Whats all missing?


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## donmattingly (Dec 10, 2011)

I am going to do it and take inferno's advice and use the brown paper on my tool bench for the dissection.   Looks like it will be a midwinter project for weekends when I am waiting for NFL Playoff games to begin. I plan on taking photos along the way to help put it all back together again and of course post updates.


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## Danno77 (Dec 10, 2011)

Glad to hear it. We can definitely help you if ou need it!

Check your PM inbox...


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## StihlHead (Jan 15, 2012)

donmattingly said:
			
		

> Thank you for all the responses. The gentleman at the shop said it was most likely bad/old gas that killed the piston and cylinder which I believe. I remember the last time I used it after the October snowstorm, I just used the mix that could have been a couple of months old. The guy also said with all the crap they put in gasoline these days, it has a shelf life of about 14 days. I will be more vigilant now.



The 'bad gas' line is typical of a bad shop/mechanic. Gas does drop in octane fairly fast, and with ethanol blended into it these days it can go bad over time. Unless you are dealing with marine engines, 14 days is a little fast for gas to go off. It shoud be fine for a few months in a land based tool like a chainsaw unless it is kept badly or exposed to heat, extreme cold, or water. I get gas to stay fresh for over a year, and can keep it fresh for up to two years. The simple solution for "bad gas" is in a small bottle on the shelf at your local auto parts or HW store. Its called Sta-Bil. It will do two things to keep your gas fresh; one is that it keeps the octane high so you will not get pre-ignition (engine knock) by keeping the lighter components in gas from evaporating away, and the other (more important these days) is that it will keep the ethanol in the gas from picking up water and separating out (phase separation) and doing damage to the fuel system and engine. 

Before I go on, no I do not work for Sta-Bil or any oil or gas addative company. I use and swear by this stuff becasue it works. The trick to using Sta-Bil is that you need to add it as soon as you buy the gas, as it cannot restore the original octane once the higher octane and more volitile components like butane and propane have wafted away. There are two types of Sta-Bil, one is the older red formula which is the one you want for chainsaws, and the other is green that is for marine engines. Either will work fine though. Add it as instructed on the label, and you will never have bad gas, even if you leave it in your chainsaw over the winter season, you live in a humid climate, or if you have 10% ethanol gas like we do in Oregon. 

As an aside, all Stihl saws made after the MS number changes sold in the US have been designed and tuned to run on crappy US grades of gasoline. Saws like Dolmar have had problems with being tuned at the factory to higher octane German gas and then imported and sold in the US and run with lower US octane gas without being re-tuned. You should re-tune your saw after filling it with whatever gas/premix oil that you use, and with whatever bar and chain you are running. Different length bars will alter the peak RPM of a saw, so you can overrev a saw if you tune it with a long bar and then put a shorter one on. I have also seen saws with scored engines that were tuned at high altitude and then brought down to lower elevation and run in denser air, causing a lean running condition leading to overheating. At 6,000 ft. elevation there is roughly 90% of the air that there is at sea level. 

Which brings me to the issue of the two main causes of engine scoring in 2-stroke chainsaw engines. One is straight gassing them. You are basically one tank away from your BIL blowng the engine by filling the tank with plain gasoline. Without premix oil in the gas the friction increases rapidly and the engine parts rub and heat up and the piston, rings and cylinder become scored. The other main cause of engine scoring is overheating from running too lean. There are several possible causes of running too lean, the main one being that the H jet on the carb is set in too far not allowing enough gas in the mix at high revs. At WOT (wide open throttle) a saw should 'burple' or 4-stroke, meaning that there is enough gas in the mix to keep it from overheating. Other less obvious ways to run your saw too lean are removing the air filter and running a saw; tuning your saw with a dirty air filter and then cleaning it; tuning your saw with a dirty muffler screen and then cleaning it, running your saw at a lower elevation than where it was tuned (we are talking several thousand feet here); running your saw out of gas (at the last minute or so that the tank is drained the saw will typically run lean and rev higher); and gas line pinching and clogging. Also if you modify your muffler you will lean it out, so you need to retune the saw after doing so. Modifying the muffler on a newer Stihl saw will require your removing the carb H limiter cap and removing the limiter tab and putting it back into the carb so it can be tuned richer. Note that no service dealer can alter a saw legally, and if they come across a saw that has been tampered with (muffler opened up, cylinder ported, limiter tabs trimmed, etc.), they must correct it or reject working on it. That is the new federal EPA law.

Just some ideas about some of the things that are blamed on 'bad gas'....


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## StihlHead (Jan 15, 2012)

A PS about bad gas... 

Other problems that can occur to the engine due to gasoline are allowing it to rev too high, or running your saw with lower octane gas than it was tuned at. Each saw has a top rev max that the saw should be tuned to using a good digital tach. Going beyond that limit is apt to damage the saw. Note that the max rev factory numbers for all Stihl saws are actually 500 RMP lower than the maximum engineered red line for all their saws. So if you know what you are doing with a tach you can set your saw to run at higher revs (and get better performance without blowing up your Stihl saws). 

Running lower octane gas can lead to engine knock (at the worst) but it may also lead to more subtle problems due to pre-detonation, cumbustion flaring, and uneven burning. These all can cause uneven pressure on the piston dome at TDC and may casue the pistion to slightly tilt to one side or the other, leading to scoring of the cylinder wall. In this case the term 'bad gas' actually applies. The result is engine scoring similar to overheating. The solution to this is to keep your gas fresh and use a gas stabilizer to keep the octane high. I also use premium gas in my saws. Higher octane will result in more even burning, and a more stable piston at TDC. I used to go to Washington State to get 100% premium gasoline there after they made all gas in Oregon a 10% ethanol blend. However, WA state now only has ethanol blended gas. 4% ethanol is all that is required to 'oxygenate' gas to lower smog levels in winter months, and that is typically what you see in gas in states like California (after they phased out MTBE). However, the corn lobby and green do-gooders all want more energy independance, so states like Oregon have gone overboard and passed laws that require 10% ethenol blends. As a result of this marine engines have had massive problems, as ethanol likes to absorb water. Once ethanol absorbs water, it likes to separate from the gasoline with the water and settle to the bottom in gas tanks, fuel lines and engines. Marine engine damage went through the roof here after they reformulated the gas here, and there has been a lot of backlash. As a result Oregon passed a law allowing for gas stations to sell pure premium gas for marine and off-road use. However, there is no mandate that they do that, so only a few stations sell the stuff and at a steep price (which is actually worth it in 2 stroke and marine engines). 

Note also that while ethnol has higher octane that gasoline, it also has a lot less energy than gasoline. About 40% less. A 10% blend of ethanol will result in 4% lower gas milage in your gar, and a noticable drop in power. It results in the same power loss in a chainsaw. Keep in mind that more octane does not mean more power from gas, it just means that it burns more evenly. Historically it ment that you could run higher compression engines and get more power out engines using higher octane gas without getting pre-ignition. Some people I know use 100 octane LL AvGas in their saws, but that stuff has lead in it to get the octane boost. I would rather not be exposed to the lead in the exhaust running a chainsaw on leaded gas. Even small amounts of lead can do damage to humans. In my view, that is what I would call, "bad gas", even though it smells really good (lead tastes sweet to humans).


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## Blasket (Jan 15, 2012)

Great posts Stihlhead!


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## Joey (Jan 15, 2012)

Blasket said:
			
		

> Great posts Stihlhead!



+2..great info


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## artmos (Jan 16, 2012)

Stihlhead-excellent post! i was about to submit a post on what octane gas i should use in my stihl saws-old and new,but you summed it up perfectly! tomorrow i fill my cans with premium.i think indiana still has 0 ethanol premium-i'm 5 miles to indiana. i will find out first. will also be sure to use sta bil more religiously in the future. thanks a bunch! art


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## StihlHead (Jan 16, 2012)

STIHL officially recommends a mix ratio of 50:1 high quality (89 US octane minimum) unleaded gasoline to premix engine oil. 89 octane is typically what is called 'mid grade gas' in the US. Octane ratings vary worldwide as to what the octane numbers mean and how they are determined. In the US, octane is rated as the average of the research tested (at the refinery when it is fresh) and the gas station tank tested (after it has been delivered by pipe, truck or rail or some combination thereof). Meaning that the octane rating here is the average between the best octane level that the gas will ever have and what it will typically be when pumped into your tank. So when gas is pumped into your tank it already is likely to have a lower octane rating than what is posted on the pump. Once it is in your tank, if left untreated, it will typically continue to fall. 

The rate at which the octane falls is influenced by the time of year that the gas is bought, and the container it is kept in. The volatility of gas in the US varies as to the time of year that it is refined. In the US we have what is called winter gas and summer gas. Winter gas is more volatle (lower vaporization pressure) and tends to have more lighter components (mainly butane) that waft off easier. Summer blends are heavier and tend to be more expensive, because butane and propane are cheap but they have to add less LP gas in summer. Which is one reason that gas is more expensive in summer than in the winter. There are 20 or 30 different seasonal blends so the actual vapor pressure requirements vary by region, and all states have their own requirements for gasoline blending on top of that, making it rather complicated. In many regions they require (or used to require) the adding of an oxegenate to gas in winter to lower smog during air inversion times. In places like California, they used MTBE to do that, but that is now banned. So they use ethenol now as an oxygenate for reducing smog year round as well as to appease the corn/ethanol/green lobby. 

I try to buy and store winter gas becasue it is lighter and better as well as cheaper. Bigger bang for the buck. It will bubble up plastic gas cans more in the heat. Plastic gas cans breathe more than metal ones do, and some recommend that you store gas in metal cans for that reason. I use both types myself. I have a staged system for premium gas for my 2-stroke powered tools. I buy premium gas in a 5 gallon plastic jug and add Sta-Bil as soon as I get it home. Highest priority; get that stabilizer in there. Now it will be good for a year. Then I pour it into two one gallon plastic jugs as needed and I add premix oil to at that time. Adding premix will lower the octane rating as well, but adding any heavier oil to gas will do that. I use Elf 100% synthetic oil that I get from a motorcycle shop. It has a blue color added so that you know if the gas has been mixed with oil. If my gas is clear, it is regular for the lawn mower or unblended super for the 2-strokes. I keep my regular gas in metal cans so that it does NOT get into my 2-stroke engines. All 2-stroke engines are only one tank full away from being scored by straight gas! I know way too many people that have straight gassed their saws to death. I have bought several of them and refitted them with new P&Cs;. 

BTW; there is much debate as to what type and how much premix oil to use. I would recommend any 100% synthetic JASO FC or FD 2-stroke oil rated for air cooled engines. Do not use MARINE 2-stroke oil! Noooooo! That is TCW rated, and is designed to run in water cooled engines. It will work in a pinch, but it will gunk up an air cooled engine over time. Read: AVOID! Also avoid any non-rated premix oil or 'all purpose' generic premix oil. They are likely to gunk up your engine, muffler screens, and foul your plugs. The same thing will happen with JASO FB rated oil over time, as I have experienced using Castrol FB premix oil. I flipped to Mobile 1 100% synthetic years ago and I noticed the difference instantly. The saws ran better, revved higher, the muffler screens stayed clear, and the engines looked better when I tore them down. I have some friends that are gold certified Stihl mechanics and they all note that even using a dyno or dyno-syn mix oil FC rated leaves more residue in the engine than 100% synthetic. Mobile 1 is not sold here any more, so I flipped to using Elf. 

Lastly there is the topic of how much oil to add to the gas. You cannot really go wrong with 50:1 as recommended. There is an old argument from us older 2-stroke enduro motocross riders that more oil makes for a better ring seal and better lubrication of the low end and hence more power. But there is a tradeoff in lower octane and less power buring more oil as opposed to gas, as well as more fouling. So I tend to use about 45:1 for slightly better ring seal, and to err on using a tad more oil than a tad less. Some run 100:1 gasil, but I would not recommend that.


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## MasterMech (Jan 16, 2012)

Wow StihlHead... Wow...  I think he's typed more in these 3 posts than I have in my last 100....

FYI: Lead is in 100LL AvGas for lubrication/valve seat wear issues amd doesn't contribute to the octane rating.  The lead leaves behind deposits.  Since the deposits keep coming, the lead never wears off the valve seats and that coating helps them seal up better too.

Many people here report great results using Star-Tron fuel additive for treating fuel against storage deterioration and phase separation.

Good points on the plastic cans breathing more than metal ones. 

Excellent on nailing Marine 2-stroke oils being used in air-cooled engines.  I've opened up a couple engines that were running marine oils and the burnt-on deposits are well, yucky. :lol:


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## Jags (Jan 16, 2012)

donmattingly said:
			
		

> Thank you for all the responses. The gentleman at the shop said it was most likely bad/old gas that killed the piston and cylinder which I believe. I remember the last time I used it after the October snowstorm, I just used the mix that could have been a couple of months old. The guy also said with all the crap they put in gasoline these days, it has a shelf life of about 14 days. I will be more vigilant now.



I think the gentleman at the shop was either full of whiskey or bull.  You pick.  Even bad gas is going to have the oil in it.  Usually the P & C gets trashed from little to no oil or mega hours.  A lean burner can do it too.  You really should be finding out WHY it happened so that you can avoid the same with the new parts.


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## donmattingly (Jan 16, 2012)

It is possible this repairman is full of bull and whiskey. This is a depressed part of NH! I have also brought my snow blower in for repair at this shop and was not too excited about the diagnosis and estimate. 

I would like to thank Stihlhead for his detailed responses! I feel as though I should print them out and use a highlighter for certain parts. All good info and I appreciate it. 

I have not pulled apart the MS 250 yet as I am knee deep in building a new bedroom. Our family is growing this June! Another helper to stack and haul wood!


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## donmattingly (Jul 10, 2012)

Well after many months of other distractions, the tear down of the MS 250 is complete! Anyone taking bets on whether or not I can put this back together?


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## donmattingly (Jul 10, 2012)

Going back to last year the repair shop declared the piston and cylinder "junk." Here is a side-by-side of the new and old piston.



And here is the new and old cylinder.


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## kenskip1 (Jul 10, 2012)

Have A look at this video.Hope this will assist you, Ken


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## Realstone (Jul 10, 2012)

Keep the updates coming Don, I'll stay tuned.


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## Ashful (Jul 10, 2012)

StihlHead: Awesome info!  But, I thought most 2-stroke oils sold for outdoor power equipment already had a fuel stabilizer additive... hence no Sta-Bil required.  No?

donmattingly: I've heard a lot of the aftermarket piston/cylinder assemblies sold for Stihl have poor fit, and thus very short life. I've seen saw shops make a big deal about using only OEM Stihl parts in their repairs, one citing this as a reason. Might be worth researching, if buying a new assembly.


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## clr8ter (Jul 14, 2012)

Cripes. Don't make it more complicated than it is......I have an Echo CS400. I buy the one-shot bottles of Echo oil. Add 1 gallon of gas & done, no measuring. Guaranteed to meet Echo requirements, and hold up the warranty. No thinking involved. I also buy the premium gas. Again, no thinking. To this gas I add StarTron additive. I have been told NOT to use Stabil red, only the marine blue. And ST is just as good. Also, for long term storage, my local shop carries Tru Fuel, gas W/O any alcohol. Lasts up to 2 years. Pricey, but worth it.

My saw has never failed to run doing this, and this spring I started out using last season's gas. No problem.


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## StihlHead (Jul 14, 2012)

Joful said:


> StihlHead: Awesome info! But, I thought most 2-stroke oils sold for outdoor power equipment already had a fuel stabilizer additive... hence no Sta-Bil required. No?
> 
> donmattingly: I've heard a lot of the aftermarket piston/cylinder assemblies sold for Stihl have poor fit, and thus very short life. I've seen saw shops make a big deal about using only OEM Stihl parts in their repairs, one citing this as a reason. Might be worth researching, if buying a new assembly.


 
2-stroke oils may or may not have gas stabilizer in them. The type of Elf oil that I use is designed for 2-stroke motorcycles, and does not have stabilizer in it. In any case, I do not believe that there is nearly enough stabilizer in any of the outdoor power equipment oil to keep the gas fesh for long periods, or to protect phase separation from happening in ethanol blended gasoline. Also if you buy and mix gas like I do, that does not work. I buy super gas in 5 gallon containers, and add stabilizer at the gas station (keep it as fresh as possible!). I then pour the gas into one gallon containers and mix it with 2-stroke oil as needed. I have never had gas go bad on me this way, and I have stored it for up to 18 months with no problems. I use the StaBil red, and it works just fine. The StaBil green formula is intended for marine use or in high water conditions if you use ethanol blended gas. The only difference is the ability for StaBil green to absorb more water and to better keep phase separation from happening with ethanol. If you use 100% gasoline or if you are in a dry environment, then the phase separation issue is not going to be a problem.

BTW: this is rather complicated stuff. Phase separation happens when water is absorbed by the ethanol blended gas, and then the water and ethanol combine and separate out from the gasoline. Combined they become a layer at the bottom of the tank becasue the water is heavier than the gas is. Basic chemistry here: gasoline is made up from several hydrocarbons that are non-polar molecules. Water molecules are polarized (one side has a more positive change and one side has a more negative charge). For this reason water and gas do not mix. Ethanol molecules have both a polarized and a non-polarized side to them. Thus ethanol will blend with either non-polarized material like gasoline, or polarized material like water. Having a choice, ethanol is attracted to water more than gasoline, and so it will separate out from gasoline with water if any water gets into the ethanol blended gasoline.

As for OEM Stihl parts, I have to agree that the tolerances on Stihl parts (Mahle, etc.) are better than most aftermaket kits. For that reason I only use mostly OEM parts on my Stihl saws. Generally I can get new or slightly used engines from a buddy of mine that works in a Stihl shop up in WA state (if I buy a scored engine saw for cheap). I do use Cabre rings from a guy in Greece that sells them on Ebay. I am not sure if they are OEM or not, but they are good rings.

Good job on that tear down! I find the 210/230/250 saws a PITA to take apart, having done several of them myself. That is one fried piston you have there.


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## WES999 (Jul 14, 2012)

One suggestion, when you have everything apart, replace the crank seals. If you have an air leak it will ruin your nice new engine. Also it is a good idea to vacuum/pressure test after reassembly.

Another thing, many times a damaged looking cylinder can be refurbished by using muriatic acid to remove the stuck on aluminum. Both my Huskies ( purchased as non runners) looked pretty bad. They cleaned up nicely with some fine sandpaper sctochbrite and muriatic acid. I think the OEM piston kit for my 36 was less than $20.

www.arboristsite.com has a lot of great info for chainsaw rebuilding.
Here is a link to what I posted describing my Husky 350 rebuild.
http://www.arboristsite.com/chainsaw/100008.htm


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## donmattingly (Aug 3, 2012)

Ok. The first issue. I cannot get the new piston into the new cylinder with the rings attach. I just won't fit. It fits fine if I take the rings off the piston. Any ideas. After reamitn the posts above, I am beginning to think I got the non Stilh aftermarket piece. Anyone have any ideas? I have come too far to quit now!


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## Danno77 (Aug 3, 2012)

It wouldn't be the first time someone was sent the wrong rings, but can you describe the method you are using to stuff the piston in with those rings on it?


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## Danno77 (Aug 3, 2012)

Oh, oh, oh. Very important note about rings on the pistons, you'll notice that the rings need to have their gaps right where the little pin looking thing sits in the piston otherwise they won't compress right.


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## Danno77 (Aug 3, 2012)




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## salecker (Aug 3, 2012)

Hi Don
 did you try to install ring with out the piston into the cyl?
 You should install the ring without the piston to measure the end gap of the ring,sometimes you need to file a little off the end to get enough clearance.To tight of end gap the piston could sieze when it gets warm.
 Good Luck
 Thomas


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## n6crv (Aug 4, 2012)

I did mine this Spring. Went from a 021 to a 250 as the saw body is the same. I did get a Stihl long block for $89.00 off of Ebay. It was what I would call a easy change over. The only bad part was getting one of the screws out of the block. Also changed the carb over to one that has the H and L adj. It seemed to really scream with the stock carb. Would do it again, as saved money and was fun to do.
Don


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## DanCorcoran (Aug 4, 2012)

I've seen videos on YouTube showing how to get a chainsaw piston and ring into the cylinder.  You might try searching there...


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## onetracker (Aug 5, 2012)

fantastic thread


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## StihlHead (Aug 5, 2012)

I saw this and thought of bad gas for some reason....


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## Realstone (Aug 5, 2012)

Proper porting could have solved that problem


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## MasterMech (Aug 5, 2012)

Realstone said:


> Proper porting could have solved that problem


 Always run with the spark arrestor screen in place! (Cue Smokey The Bear.....)


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