Stihl MS250: end of the road?

[SteveSr]

While we are talking about performance improvements... You might want to consider using or switching to a low profile 3/8" pitch .050" narrow gauge B&C. The saw will cut much more like a MS260 when set up like this. Don't understand why Stihl would put a .325 .063 18" setup on a 45cc saw. I think they wanted to sell more 260s since it had 33% more HP to pull that B&C!

 

[bitsumishi]

Thanks guys. Quite often as the saw got older but with the saw running at it's best, I did find that on larger logs, it would tend to bog down halfway through the cut on our very hard gums, so an upgrade to the carb and a lower profile chain might be just the thing. With the great power to weight ratio (and low bulk) of the 250, these mods could turn it into the ultimate saw for me. Even it's direct replacement, the newer 251, is heavier and bulkier and at $700 US in Australia, is a lot of money and quite a lot more (nearly double) than they cost in the US.

My other option could be to get a new 250 from the US (they are discontinued in Australia but still made in the US) for around $320 US. 'Cos the risk is as someone mentioned, I could replace the carb only to find I have engine issues, which is something I have never re-built before on anything. And at the end of the day I will still have a 10 year old saw....and my guess is that they weren't as well built then, as the older saws people are keeping alive.
My only concern with a new 250 is that they will have messed around with the carb and muffler for EPA regs, making it less of a saw than the one I have?
Plus I have the very real problem of finding a Stihl dealer who will a) post me a new saw (they usually insist on the buyer being there and getting a demo on the saw) and which has never had fuel in it (for air freight regs).
Perhaps the most attractive option is to get a new 250 from the US and change out the carb to the Walbro, mod the muffler and change out the B&C. The only remaining issue I would have to solve would be the freight problem.

 

[SteveSr]

There is little on that saw that can't be fixed with a T27 Torx and a little bit of knowledge which you can get right here. Even if the crank seals are bad they are easily replaced by removing the engine pan and then resealing everything with Dirko HT.

Start with the carb, fuel line, & filter. If that doesn't fix it then worry about what is next.

 

[bitsumishi]

There is little on that saw that can't be fixed with a T27 Torx and a little bit of knowledge which you can get right here. Even if the crank seals are bad they are easily replaced by removing the engine pan and then resealing everything with Dirko HT.

Start with the carb, fuel line, & filter. If that doesn't fix it then worry about what is next.

Ok

 

[HarleyT]

Thanks guys. Quite often as the saw got older but with the saw running at it's best, I did find that on larger logs, it would tend to bog down halfway through the cut on our very hard gums, so an upgrade to the carb and a lower profile chain might be just the thing. With the great power to weight ratio (and low bulk) of the 250, these mods could turn it into the ultimate saw for me. Even it's direct replacement, the newer 251, is heavier and bulkier and at $700 US in Australia, is a lot of money and quite a lot more (nearly double) than they cost in the US.

My other option could be to get a new 250 from the US (they are discontinued in Australia but still made in the US) for around $320 US. 'Cos the risk is as someone mentioned, I could replace the carb only to find I have engine issues, which is something I have never re-built before on anything. And at the end of the day I will still have a 10 year old saw....and my guess is that they weren't as well built then, as the older saws people are keeping alive.
My only concern with a new 250 is that they will have messed around with the carb and muffler for EPA regs, making it less of a saw than the one I have?
Plus I have the very real problem of finding a Stihl dealer who will a) post me a new saw (they usually insist on the buyer being there and getting a demo on the saw) and which has never had fuel in it (for air freight regs).
Perhaps the most attractive option is to get a new 250 from the US and change out the carb to the Walbro, mod the muffler and change out the B&C. The only remaining issue I would have to solve would be the freight problem.

Don't fixate on the Walbro thing too much.

 

[HarleyT]

Finish blowing out your old carb, take off that yellow limiter, put it back together, and put it back on the saw and try it. After it is back on, turn both screws out 1/2 turn and run the saw rich a bit, then adjust.

 

[bitsumishi]

Finish blowing out your old carb, take off that yellow limiter, put it back together, and put it back on the saw and try it. After it is back on, turn both screws out 1/2 turn and run the saw rich a bit, then adjust.

Ok

 

[SteveSr]

Finish blowing out your old carb, take off that yellow limiter, put it back together, and put it back on the saw and try it. After it is back on, turn both screws out 1/2 turn and run the saw rich a bit, then adjust.

Since the "L" screw is unlimited the stock setting should be printed on the side of the saw or in the manual. For the "H" screw since it is rotationally limited there is usually a "bias" built into the needle setting BEFORE the limiter cap is installed. This bias may be carburetor model dependent.

I just checked my MS250 service manual and it says "L" is one turn and "H" is 3/4 turn without removing the limiter cap. It also doesn't mention which carb model. Oh well...

Searching the Tech Notes I found the one that introduced your carb model. You can read the attached details which shows the stock setting to be 1 1/2 turn on the "H" needle with the limiter fully CCW.

A stock saw should run properly at or near sea level with the stock carb settings. An erratic idle or the "L" screw needing to be opened considerably further than stock may indicate an air leak somewhere.

 

[bitsumishi]

Since the "L" screw is unlimited the stock setting should be printed on the side of the saw or in the manual. For the "H" screw since it is rotationally limited there is usually a "bias" built into the needle setting BEFORE the limiter cap is installed. This bias may be carburetor model dependent.

I just checked my MS250 service manual and it says "L" is one turn and "H" is 3/4 turn without removing the limiter cap. It also doesn't mention which carb model. Oh well...

Searching the Tech Notes I found the one that introduced your carb model. You can read the attached details which shows the stock setting to be 1 1/2 turn on the "H" needle with the limiter fully CCW.

A stock saw should run properly at or near sea level with the stock carb settings. An erratic idle or the "L" screw needing to be opened considerably further than stock may indicate an air leak somewhere.

Thanks Steve. I was going to measure the current positions of the screw heads out from the body before I remove them to clean inside. Not very technical I know, but it will give me a starting point when I put them back, I guess.

 

[bitsumishi]

I....er.....got a bit carried away.

 

[cedarhollow]

Good job mate, Stihls are not that hard to work on any you have the best experts on the planet helping you out. Best of luck with it.
I had no idea the price difference from US to AUS.
Yesterday while looking at online classified ads I came across an MS260 in absolute mint cond from a homeowner for $225, which is low here but not $1000
Your taking the bull by the horns by doing repairs yourself and will never again get ripped off by a local shop.

 

[bitsumishi]

Best of luck with it.
I had no idea the price difference from US to AUS.

Thanks.
Believe it or not I paid nearly $600 USD for this saw 10 years ago. Considering I have only used it say once a month in the winter, that's only about 50 to 60 times I have used it in all.
Putting it in the trash or selling it as not working on the net for $20 would be just wrong.

 

[bitsumishi]

Ok I think I have found a problem not necessarily the only one though. As I posted a while back, when pulling the starter it would often get stuck half way and was kind of lumpy all the way through the pull.
I think a cause is the flywheel rubbing (the edge is worn and shiny, its not just the flash):



There is some wobble in the bearings, probably about 1-2mm side to side.

 

[HarleyT]

Real hard to do with the engine apart like that. Might take an extra person with a deep well socket and hammer,
on the flange head nut, while the other guy holds the flywheel.

 

[bitsumishi]

Real hard to do with the engine apart like that. Might take an extra person with a deep well socket and hammer,
on the flange head nut, while the other guy holds the flywheel.

Thanks. Managed to get it off. I think the bearings have gone....just found out they were made partly out of plastic, I will never buy Stihl again.

 

[bitsumishi]

Ok so I suspect that the pile of parts is going in the trash....if there is wear in the bearings, there is probably wear in the shaft and there is wear on the flywheel and I still suspect that the carb needs replacing. Considering the amount of hours this saw has done...about 200, I dont think I got very good value for money and I suspect it is pointless spending money on it.

I am thinking about the 43cc Makita but I will have to import it as that model isn't available here.

 

[SteveSr]

Well... You did the disassembly in the wrong sequence. The clutch and flywheel are supposed to come off first using a rope or piston stop to hold the piston. The bearings are probably only bad if the plastic ball carrier is physically broken. Plastic ball carriers are fairly common in saw bearings. I don't think it is quite as hopeless as it looks.

 

[SteveSr]

I am thinking about the 43cc Makita but I will have to import it as that model isn't available here.

No dealers = No source of parts or consummables

 

[bitsumishi]

No dealers = No source of parts or consummables

For some reason Makita bring in the 32cc and a 45cc (quite a lot heaver than the 43cc) and nearly as heavy as my 61cc Makita.
It may be that the consumables are interchangeable with the models either side of the 43cc. It's either that or the 445 Husky but that still means importing it as they are prohibitively expensive here.

 

[bitsumishi]

Well... You did the disassembly in the wrong sequence. The clutch and flywheel are supposed to come off first using a rope or piston stop to hold the piston. The bearings are probably only bad if the plastic ball carrier is physically broken. Plastic ball carriers are fairly common in saw bearings. I don't think it is quite as hopeless as it looks.

I put the case back on and used a rope to hold the piston in place and I removed the clutch and nut on the flywheel so no I didnt do it in the wrong order...I took the pictures before I put the case back on.
The bearings have side to side movement on the shaft so they are worn. And because they have movement, they have probably caused wear on the shaft which probably means they would all need replacing. There is wear on the flywheel. I wont use non genuine engine parts except where there are better quality non genuine available as in the case of the bearings. There appears to be a fuel issue which means the carb needs to be replaced. The Walbro carb isnt available in Australia except from Stihl at around $100 USD. If I import it from the US, it will take around 2 weeks to get here and cost me only slightly less by the time I have added the post. I have no logs for winter and it is getting cold. I dont have several weeks spare in the hope that I can fix this saw at the end of it.
The US/China aftermarket carbs may not be suitable for the Au muffler, so it means the genuine Stihl at around $100 US. A new MS250 from the US costs just over $300...I cant see there is any point in spending 1/3 to 1/2 of the cost of a new saw, on a 10 year old one which has already proven itself not to be reliable even after low hour usage. Doing the same thing again and again, in the hope of a different result, is the definition of insanity.
I think this saw is toast and is not worth either the costs or any more time, spent on it.