Stihl MS261-CM 2020 4 months old scored piston???

[Stihl-Bummer]

Stihl 26RS or 26RM is what I'd be using. RM will stay sharper longer, but won't initially cut as aggressively. Make sure the chain color code is yellow, as the way you're cutting, you're using part of the tip. Green chain doesn't cut well on the sprocket tip.

Keep in mind, if you start using skip tooth chains, you're actually removing load from the saw. Lack of load is why you were running it part throttle. Full throttle with a moderate load is what I'd be shooting for. Stihl RS or RM chain will easily get you there, just make sure they are sharp and depth gauges are set correctly. Control the engine load by varying downward pressure and feed rate. When I'm milling with my 661, there is a specific engine pitch I shoot for...not screaming and not bogging.

Thank you

 

[SteveSr]

Putting a laser temp on the engine will also be a good idea I’ll stop halfway through the project measure the temperature and just make sure it’s not getting excessively hot.

You have to do this while the saw is under load for a meaningful result. Get a helper to watch the temperature while you mill.

 

[Yukon Stihl]

When I go pick it up in two weeks I will ask to see it. And take photos.

Ask for all the old parts...
You may be able to save the cylinder for future use,or pass it along for someone to try and save.the dealer will just toss it.

 

[drf255]

In your personal opinion what makes you like dominator over the saber oil do you use dominator in your chainsaw.

Personal observations as well as those from others here I trust. After pulling saws that were ported apart to look for more gains, Dominator/Red Armor left everything very wet and lubricated. Others didn’t work out as well. This included saws used solely for milling as well. Not looking to start an oil thread, it’s just my opinion. I have used Saber and really had no complaints, it’s just not as great As dominator.

 

[Kyfan]

Sounds like I need to buy a stronger saw than a 50.2cc.

This is how it starts next thing you know he's gonna have a 15 saws and be discussing the finer points of amsoil vs Lucas oil at a 33.2586/1 mixture measured with a spectrometer.

Seriously though get you a big saw when you've got the funds. They are alot more fun to use especially for the stuff you are discussing.

 

[SAWMIKAZE]

Again I’m still very glad that they’re repairing it they could’ve just straight up told me it’s all my fault but they’re willing to work with me which is awesome. And of course the manual says offload don’t redline but I was also recommended even while cutting don’t go full throttle the entire time just be a little bit less as the new parts set in for the first three tanks. I read that manual from cover to cover as I honestly love the chainsaw and want it to last for several years. However I will be doing things differently when I get it back the second time.

You got bad advice. But with the advice you have now been given you'll be in good shape if you apply it.

 

[Stihl-Bummer]

Hello everyone just wanted to let you know I got my chainsaw back weeks ago. I’ve been running 3 ounces of oil and full throttle no matter what I’m doing. I removed the spark arrester, and did the muffler mod by putting three slits in the side with a Dremel. I used the Stihl yellow chain, a skip tooth chain only offered on eBay and Oregon PowerCut. I have finished making the Beams they are 6 x 8. And I must say the Oregon chain perform better than all the chains I was really surprised. Either way thank you all for all the information you gave me

 

[esean]

Hopefully you had the muffler off the saw and washed it out after cutting the slits. You don't want to risk metal shavings or grit getting into the cylinder.

 

[LegeaDejului]

In your personal opinion what makes you like dominator over the saber oil do you use dominator in your chainsaw.

OP, Amsoil Dominator has no rust inhibitor, its made for engines that are taken apart often, I had friends that had their saw's bottom end develop rust after storage when using this oil. There are people on here that posted about this same issue, its not a chainsaw oil, period. If you really wanna go Amsoil, go with Saber. I don't personally like it as it creates deposits in my engines no matter the tune, also in my m-tronic. I don't bother with it no more. In my opinion, go with HP Ultra at 40:1 or Motul 800 40:1. I recommend motul when milling due to higher flash point which should in theory help with the high temp lubrication. These fully synthetic ester oil are really great.

 

[echomeister]

So if you need to cut something small that won't really load the engine do you still pull the throttle wide open?

I would think part throttle would be OK in this situation. But I don't know nuthin.

 

[KodiakForge]

I’m sorry you had a bad experience, but glad to hear your getting it all fixed up. I also wanted to share a few things with you that could help you enjoy your fixed saw for a longer timeframe than your first go around. I’ll start by saying that the saw you have is severely underpowered for the kind of tasks your putting it through. I hate to say it, but while you followed the instructions, there is also a lot of things that were done (I don’t want to say wrong) but certainly could have been done differently . I’m not trying to pick on you or make you feel bad, just trying to share some info in a learning moment and potentially preventing the same thing from happening again.

1.) big wood like you cut (4’ diameter hardwood) while it can be done with a smaller saw it does create a lot of extra drag and really works the saw out, and your better suited to upsize if your going to do much more of that kind of cutting as it can cause over heating

2.) milling is extra tough on saws and will shorten the life of any saw in any size when used consistently in that manor compared to making standard cross cuts. This is because your cutting parallel to the grain instead of perpendicular to it. I’m sure you noticed the chips looking more noodle like instead of like actual chips. One other thing that likely worked against you I s that the grind angle on standard chain vs ripping or milling chain is quite different. Ripping chain has a much more shallow angle to it so as to not bite into the wood as much causing the saw to be overworked. Here is a link with good info: http://www.madsens1.com/bnc_rip.htm

3.) new epa saws in general run hotter than older pre epa saws, therefor they can suffer over heating easier especially when used in the ways you used it.

4.) warming the saw up before use is very important too before getting into cutting. Anything that heats up expands, so if you start the saw and get right into some wood your piston can/will actually change shape becoming oval as it heats up causing scoring on piston, cylinder or both. This expansion typically happens on exhaust side first as that’s where the heat is at.

5.) sharp chain is critical to saw performance and the life of a saw. While one might sharpen chain after every use, it may be that your angles, gullet depth or rakers are off. It’s all about the geometry and not just the going through the motions of filing if that makes sense. There are many ways to sharpen a chain and much of that info and tooling gizmos are completely useless and will lead you astray while some is completely invaluable. For example DO NOT count your filing strokes and do equal strokes on each tooth, that will screw you big time. Filing is an art and something all saw owners should strive to master. If you happen find yourself on you tube trying to learn to file a chain BE CAREFUL there is lots of bad info out there. I highly recommend
Buckin Billy Ray’s channel as he’s a logger/tree man and he explains filing in a very understandable way geared to help people understand the science who might not have much time on a saw but want to learn right the first time. It’s far easier to share a video than explain the process on here so have a look at some of his filing videos.

I hope some or all of this helps you and I hope your next go around with the saw is a much better experience.

 

[farmhard]

What type of chain did you mill with? It seems to me I have one of those saws here with a burned up cylinder also and I was having a hard time finding a jug "reasonably" but there was 2 different style jugs and I had the one worth more than the saw lol.

 

[farmhard]

So if you need to cut something small that won't really load the engine do you still pull the throttle wide open?

I would think part throttle would be OK in this situation. But I don't know nuthin.

2 strokes like WOT. So do clutches.

 

[farmhard]

I'm kind of surprised they didn't swab for ethanol and decline the warranty tbh.

 

[JimmyT]

I'm kind of surprised they didn't swab for ethanol and decline the warranty tbh.

Farmhand, I thought Stihl allowed 10% ethanol in their fuel. 50 to 1 is not going to cut it in high performance saws especially when you are loading the saw like milling in July and August. I'm sold on 93 Octane ethanol free with a good full synthetic oil. I've been running Motul 800 2T and Maxima K2 but they were producing to much carbon so I switched to Yamalube 2R at 32 to 1 and no P&C scoring in Dolmars PS-5105SC and Husqvarnas 346XP
turning 14,500 rpm's in 15 years.

 

[farmhard]

Farmhand, I thought Stihl allowed 10% ethanol in their fuel. 50 to 1 is not going to cut it in high performance saws especially when you are loading the saw like milling in July and August. I'm sold on 93 Octane ethanol free with a good full synthetic oil. I've been running Motul 800 2T and Maxima K2 but they were producing to much carbon so I switched to Yamalube 2R at 32 to 1 and no P&C scoring in Dolmars PS-5105SC and Husqvarnas 346XP
turning 14,500 rpm's in 15 years.

I was being sarcastic. Our Stihl dealer wouldn't have the parts to do this job for 3 weeks. They don't stock fuel hoses or oil lines, clutch needle cages or just about anything I ever ordered.

 

[JimmyT]

I was being sarcastic. Our Stihl dealer wouldn't have the parts to do this job for 3 weeks. They don't stock fuel hoses or oil lines, clutch needle cages or just about anything I ever ordered.

I know exactly where you are coming from since Makita stopped production of all saws on March 31st 2022 availability for Dolmar and Makita parts has really slowed down. I have a friend that has worked at the Dolmar/Makita Plant in Hamburg Germany for 40 years and he told me that parts would only be available for 7 years so we only have just a little over 5 years left. It's going to be hard to throw that 7900 into the dumpster when the time comes.

 

[huskihl]

I know exactly where you are coming from since Makita stopped production of all saws on March 31st 2022 availability for Dolmar and Makita parts has really slowed down. I have a friend that has worked at the Dolmar/Makita Plant in Hamburg Germany for 40 years and he told me that parts would only be available for 7 years so we only have just a little over 5 years left. It's going to be hard to throw that 7900 into the dumpster when the time comes.

They’re required by law to make parts for 7 years after discontinuing a model but don’t appear to be abiding. It’s nearly impossible to get some parts already

 

[JimmyT]

They’re required by law to make parts for 7 years after discontinuing a model but don’t appear to be abiding. It’s nearly impossible to get some parts already

You are 100% correct the 181-143-210 14,500 rpm coil for the 5105SC was discontinued January of 2019. I guess that is a gray area since the last Dolmar PS-5105SC rolled off the production line February 28th 2010 and EPA was bearing down on them.

 

[bwalker]

Farmhand, I thought Stihl allowed 10% ethanol in their fuel. 50 to 1 is not going to cut it in high performance saws especially when you are loading the saw like milling in July and August. I'm sold on 93 Octane ethanol free with a good full synthetic oil. I've been running Motul 800 2T and Maxima K2 but they were producing to much carbon so I switched to Yamalube 2R at 32 to 1 and no P&C scoring in Dolmars PS-5105SC and Husqvarnas 346XP
turning 14,500 rpm's in 15 years.

Both of those oils are clean burning. If you have lots of carbon you have a tuning issue.