Compression loss over time...

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I wanted to see if I had any lose since the last time I did the test 2 years ago (145 psi) on the ms290. Same. No lose at all.

Saw has been taking more pulls to start. Pretty reliable after 7 to 8 pulls. Use to be 4 to 5. I guess it is not engine wear. Something else. Any ideas? Gas? Mix ratio? 2 Stoke Oil brand? ???
 
I wanted to see if I had any lose since the last time I did the test 2 years ago (145 psi) on the ms290. Same. No lose at all.

Saw has been taking more pulls to start. Pretty reliable after 7 to 8 pulls. Use to be 4 to 5. I guess it is not engine wear. Something else. Any ideas? Gas? Mix ratio? 2 Stoke Oil brand? ???

Filters (air and fuel)? Plug?
Have you changed gas, mix ratio or oil brand to coincide with the change in starting?
 
Filters (air and fuel)? Plug?
Have you changed gas, mix ratio or oil brand to coincide with the change in starting?

I changed from 44:1 to 50:1 that helped out some bogging issues. I thought that maybe the less oil has brought about more engine wear, and this is NOT the case. The last mix was with some Husqvarna Oil. Next mix I will go back to a mix with Stihl Synthetic, that initially had a big improvement. I used all that up, and tried the Husqvarna, which now coincides with this starting issue. It seems that any problems occur with the ms290. The ms461 performs GREAT with whatever I put in that saw.
 
Not a mechanic but it seems some engines are more particular than others with what you feed them.

Not trying to convert this to an oil or gas thread, but my saws seem to run better and more consistently when I change to non-E and full synthetic. I assume due to less fouling. I also noted a positive change when I switched from Stihl Ultra to the former Dolmar brand. I can’t offer an explanation for that one. I changed the mix only because of a real deal when they closed out the Dolmar name. The perceived performance improvement was a complete surprise.

Hopefully, you can fix your problem by going back to the pre-issue mix.

Ron
 
The ms290 is now in its 9th year of service. Seems about 2 or 3 years ago it started getting a bit fussy. I still really enjoy the saw, but see it as a challenge to figure out what keeps it from performing like it once did. I'm going to try the Stihl synthetic and see. After that, and the problem persists, it is most likely something I will just live with. I was surprised that the compression is still holding firm. A real solid saw with some minor quirks.

I can say with certainty the going from 44:1 to 50:1 has completely fixed the bogging issue.
 
I don't see where the carb has ever been rebuilt but like other things it does need work every so often. Little passageways inside, rubber or plastic diaphragms get a little stretched. The throttle shafts start leaking a little (especially if you are a throttle bipper). So many little things add up to not running like a new one. It happens gradually so we tend to adjust. 9 years of service to you should deserve a little TLC.
 
I don't see where the carb has ever been rebuilt but like other things it does need work every so often. Little passageways inside, rubber or plastic diaphragms get a little stretched. The throttle shafts start leaking a little (especially if you are a throttle bipper). So many little things add up to not running like a new one. It happens gradually so we tend to adjust. 9 years of service to you should deserve a little TLC.

I was thinking earlier today, that it might be the carb. I am going to call the dealer tomorrow and see about buying a factory Carb. With the engine being so strong, maybe a new carb will get me another 9 years of firewood cutting with this ms290.
 
X2 with carb issues... a carb kit is cheap. And the diaphragms get stiff with age. No way to stop that. If you dont get actual results from Adjustments it's time for a kit.

Actually I do have a carb kit, but it is a China cheapo kit. I don't know if I care to be messing with this work horse with questionable parts. At least not til I get a quote on factory part prices.
 
Maybe. The idle is a little high right now. There has always been a lag with the throttle, and I have messed with the carb adjustments many times over the years, with no real or positive effect.



If you open up the low1/4 turn or so and it doesn't slow the saw down or improve throttle response plus make it start better your carb is clogged and needs work. Opening the low up a little is the first thing to try. Steve
 
I don't see where the carb has ever been rebuilt but like other things it does need work every so often. Little passageways inside, rubber or plastic diaphragms get a little stretched. The throttle shafts start leaking a little (especially if you are a throttle bipper). So many little things add up to not running like a new one. It happens gradually so we tend to adjust. 9 years of service to you should deserve a little TLC.
Good post. I am a crazy throttle blipper when limbing. I agree too after 9 good years of service a saw deserves some $$ put into it. And while a carb kit usually fixes carb issues, they are quite mechanical little things, I'd buy a new OEM carb then everything is new.
 
Your problem is probably due to the main fuel control diaphragm getting stiff. I have used MANY carb kits from China and have never had a problem with their quality, diaphragms and gaskets seem to made of same material as OEM, just have to be sure you are using the right ones. For those who keep badmouthing China kits, do you know where the OEM kits were made? It would be helpful if you could state the exact problems you have had rather then just passing them off as cheap junk.
 
Your problem is probably due to the main fuel control diaphragm getting stiff. I have used MANY carb kits from China and have never had a problem with their quality, diaphragms and gaskets seem to made of same material as OEM, just have to be sure you are using the right ones. For those who keep badmouthing China kits, do you know where the OEM kits were made? It would be helpful if you could state the exact problems you have had rather then just passing them off as cheap junk.
CHINA!
 

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