026 vs 028 For First Saw

[Hickahollar]

If I ever wear out my ms250 Ironhorsedoctor I'll probably buy something like a ms261 and rebuild my ms250. That thing is probably 10 maybe 11 years old now I can't remember when I bought it. It was sometime around 2012 give or take a year. I haven't used it as much since I got the ms362. I fell with the 362 run it until it runs out of gas then I use my 250 then if I need it I get either my pl3314 poulan or my little echo cs3510 then I take a needed break. So for the last 3 years the 250 has only seen about 1/3rd the work it used to. I cut 4 or 5 cords of wood for me each year. Then probably another 3 for my mom. Then If I can sale an extra cord or 3 from storm clean up each year I will. Some years people tell me 150 is too much so I have extra camping wood and other years people want 5 plus cords. If I stay in saleing firewood I'm gonna just say 250 a cord 200 if you drive to me and get it.

 

[Courage]

Well how is the 260 doing? Congrats on your saw. I have a ms250 and ms362. The 250 is about 1 hp less but similar weight. It's been really good for me. If it ever goes I hope they still have a ms261 to sale.

Hey, sorry for never responding! I didn't see your question till I was going back through old posts, and realized I never responded...
It was doing great, and hopefully will be again soon. The second to last time I used it, it started bogging down mid cut which was kinda weird. I had been running it hard for about 2 hours solid (processing a 24" fir) so I let it sit and cool down, and then it seemed to go back to normal. Then, last time I ran it (earlier this week) it started acting weird on the 10th-ish cut on 20" pine. It was acting like it was running out of gas with a full tank. Sounded and felt lean to me. More of a high pitched sharp sound, super rev happy, but zero power. Thinking I'll give a new fuel line, fuel filter, and impulse line a try. Hoping that fixes it. Then, I really want to muffler mod it. I've never tuned a carb before. From my understanding, when tuning from a muffler mod, it needs more fuel, right? If that's the case, I shouldn't really have to worry about doing something wrong and melting it down, right, if all I'm doing is richening it a little?

 

[fields_mj]

Hey, sorry for never responding! I didn't see your question till I was going back through old posts, and realized I never responded...
It was doing great, and hopefully will be again soon. The second to last time I used it, it started bogging down mid cut which was kinda weird. I had been running it hard for about 2 hours solid (processing a 24" fir) so I let it sit and cool down, and then it seemed to go back to normal. Then, last time I ran it (earlier this week) it started acting weird on the 10th-ish cut on 20" pine. It was acting like it was running out of gas with a full tank. Sounded and felt lean to me. More of a high pitched sharp sound, super rev happy, but zero power. Thinking I'll give a new fuel line, fuel filter, and impulse line a try. Hoping that fixes it. Then, I really want to muffler mod it. I've never tuned a carb before. From my understanding, when tuning from a muffler mod, it needs more fuel, right? If that's the case, I shouldn't really have to worry about doing something wrong and melting it down, right, if all I'm doing is richening it a little?

I'd check that saw for a vacuum leak. Loosing the tune like that is a good way to loose the top end.

 

[Courage]

I'd check that saw for a vacuum leak. Loosing the tune like that is a good way to loose the top end.

That's what I was thinking too, so I quit running it. I'm a newbie to working on saws. Could you tell me how to go about testing for a vacuum leak? Thanks! And sorry for the ignorant question!

 

[StihlsawuserMS361]

Look at "Vintage Engines Repairs" , both on this site and YouTube.

 

[Courage]

Look at "Vintage Engines Repairs" , both on this site and YouTube.

Thanks! Will do!

 

[fields_mj]

That's what I was thinking too, so I quit running it. I'm a newbie to working on saws. Could you tell me how to go about testing for a vacuum leak? Thanks! And sorry for the ignorant question!

No need for apologies. Ignorance is why a smart person asks questions. I've not done it very many times, but the first 2 min of this video describes how I do it.



He only does a pressure test, but you also want to do a vacuum test. He also goes into diagnosing exactly where the leak is coming from. I don't go that far. So long as my base gasket/seal is good, then a leak means that I'm replacing my bearings and seals. Bearings are generally around $20 each from the dealership, and a gasket kit that includes the seals should also run around $20. If I'm into it that far, IMHO its worth spending the extra money to just replace it all.

This is what I bought to do the test.

https://www.amazon.com/dp/B0B1BPSZFF?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

 

[Courage]

No need for apologies. Ignorance is why a smart person asks questions. I've not done it very many times, but the first 2 min of this video describes how I do it.



He only does a pressure test, but you also want to do a vacuum test. He also goes into diagnosing exactly where the leak is coming from. I don't go that far. So long as my base gasket/seal is good, then a leak means that I'm replacing my bearings and seals. Bearings are generally around $20 each from the dealership, and a gasket kit that includes the seals should also run around $20. If I'm into it that far, IMHO its worth spending the extra money to just replace it all.

This is what I bought to do the test.

https://www.amazon.com/dp/B0B1BPSZFF?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Thanks for being willing to help a newbie out! I appreciate it! I picked up a vacuum pump from Harbor Freight yesterday, but it was the same price as the one you linked, and doesn't have a carrying case, and just looks cheaper quality, so I think I'll return it and get the one you have.
Will you explain the importance of a vacuum test instead of a pressure test? It seems like they would accomplish the same thing, but my curious mind wants to know...
That video was very informative! Thanks!
One question I do have though, the test isolated the engine from the carb and fuel/impulse lines. Couldn't a leaky carb or rubber lines cause the same problem of extra air in the case? Am I missing something? Just trying to understand everything before I start taking my saw apart... I think I read somewhere that oem rubber parts are typically good for 5 years, but that aftermarket rubber parts typically fail around the 3 year mark. Before I bought the saw, they previous owner replaced the fuel and impulse line with aftermarket parts. I bought the saw about 3 years ago, and I'm not sure how long before that he had replaced them... should I replace the fuel and impulse line and see if that fixes it before doing a vacuum test, or is that risky as far as running it again without it for sure being fixed?

 

[fields_mj]

Thanks for being willing to help a newbie out! I appreciate it! I picked up a vacuum pump from Harbor Freight yesterday, but it was the same price as the one you linked, and doesn't have a carrying case, and just looks cheaper quality, so I think I'll return it and get the one you have.
Will you explain the importance of a vacuum test instead of a pressure test? It seems like they would accomplish the same thing, but my curious mind wants to know...
That video was very informative! Thanks!
One question I do have though, the test isolated the engine from the carb and fuel/impulse lines. Couldn't a leaky carb or rubber lines cause the same problem of extra air in the case? Am I missing something? Just trying to understand everything before I start taking my saw apart... I think I read somewhere that oem rubber parts are typically good for 5 years, but that aftermarket rubber parts typically fail around the 3 year mark. Before I bought the saw, they previous owner replaced the fuel and impulse line with aftermarket parts. I bought the saw about 3 years ago, and I'm not sure how long before that he had replaced them... should I replace the fuel and impulse line and see if that fixes it before doing a vacuum test, or is that risky as far as running it again without it for sure being fixed?

Personally, I'd keep the tester you have. There's nothing wrong with it. I didn't end up liking the vacuum side of that tester. I thought I bought my vacuum tester from Amazon, but I just realized that when I didn't like it, I bought the one from HF and liked it a lot better.

You need to seal the exhaust and intake ports as demonstrated in the video. That will remove the carb from the process.

You're more likely to have a vacuum leak than a pressure leak. Pressure will push against the seals and often cause them to seal up and hide a small leak. Vacuum will pull against the seal and cause it to leak more easily. When the saw is running, the leak actually occurs while the crank case is under vacuum. The additional air is what causes the saw to run lean. At least that's my understanding of the process.