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is this where the chainsaw nerds hang out?
i got this stihl 021 free from a friend. its been stored inside for around 8 years in a case.prior to that it was barely used. surprisingly some new gas and it started right up.it ran perfect for around 15 minutes, idled and throttled up fine. it needed a bar and the fuel tank vent so i went and bought those and installed them. i started it up fine and i cut up a few logs i had lying around just to test it. i shut it off and took the bar off again to clean out the chain side because it was fairly dirty and i was concerned about the bar oiling correctly. put it back together, started it up and now it bogs at WOT. it still idles well and runs good at half throttle, just not wide open. the 2 stroke fuel i actually got from a lawn service guy who didnt speak english so i am unsure of the mix, but considering it ran so well at first i dont think its the fuel. it has the 2 screws to adjust the carb but i havent touched them.
i work on cars for a living and am pretty good with mowers but im pretty clueless when it comes to 2 stroke engines. thanks for any help you can give me

well since it ran fine before i would say you either got the chain to tight or the guides in wrong or something in a bind if not then adjust the high speed screw in the carb see if that makes a difference but i would look at the chain first since it did run fine before you took it back apart

i had that thought as well. i ran it with the chain off to check and it does the same thing. i found some other threads that say to clean the spark arrestor which i will do tomorrow. also ordered a fuel line (which could also be the problem it seems) and a fuel filter. just seemed like a good thing to do since it has been sitting so long. i called the guy i got it from and it seems they bought it and only cut down one tree and bent the bar and it has been sitting since the early 2000's. so it seems like if i can get it running good ill have an almost new saw for the price of a bar! also how tight should the chain be?

good luck with it i have always ran my chain snug to the bar but if i pull up on the chain i can see between it and the bar thats the way i was bought and have never had a problem with that

well took the spark arrestor screen completely out for testing and same deal. i didnt think it was the problem as it wasn't very dirty. i hope it is the fuel filter or line which should be in tomorrow or monday. i had a thought that maybe the fuel could be like a 32:1 mix (worst case scenario) would that cause this problem? also any idea what the stock settings on my two adjustment screws should be?

Basic setting is around one and a half turns, that would get it to start up, but I don't think its the settings, and I would leave them there, it as not been in use for a few year's and I know you have manage to have it to run, but so I would inspect the diaphragm/metering diaphragm for damaged/leaking or shrunk and also gasket(s), and replace if necessary, take the carburetor off and have a look, am sure it will need a good clean out. you say you don't have full throttle, that's a sign that maybe the jet's need a good clean out.

hair line crack in fuel line. Replace it they fail all the time.

Rob

yeah i ordered the fuel line and filter from ebay, should be in today. If that doesn't fix it i guess ill have to pull the carb to check the diaphragms.

so i finally got around to putting the fuel line and filter in today. at first when it was cold it seemed to be running good but as it warmed up, same deal. no power at wide open throttle and if you try to cut any wood it stalls. so at this point im probably looking at a carb rebuild. while i was putting in the fuel line i had the carb off and it appears to be a walbro 215. where is the best place to buy the kit? while i had the carb off i took off the 4 screw cover just to see what it looked like and the diaphragm was intact but had some wrinkles/ stretched looking places in it, is that what a bad one looks like? i have never rebuilt a carb this small, but there is a guy with a video on youtube and it doesnt look too difficult. anything in particular to watch out for?

Going by the Stihl Workshop Manual the 021 is not fitted with a Walbro 215 (see photo) anyway am sure you can do the job you just need to take you're time, and remember how you take things off...!.
Anyway I have the info you need so when you have the parts, come back send me a PM with e-mail address and I'll send it to you.

thanks. i ordered a kit off of ebay that says it covers the 021 and alot of other models. the pic has something like 9 different gaskets as well as the screen and needle and lots of other parts. hopefully it will have what i need. seemed like a deal at $8 with free shipping. there were cheaper ones but you had to be sure of the carburetor number, this one said it covered them all.

Make sure when you clean the carb there are no bits of old gasket left anywhere, make note in how you take things off, and let one know you have the parts.

cheapsaw said:

so i finally got around to putting the fuel line and filter in today. at first when it was cold it seemed to be running good but as it warmed up, same deal. no power at wide open throttle and if you try to cut any wood it stalls. so at this point im probably looking at a carb rebuild. while i was putting in the fuel line i had the carb off and it appears to be a walbro 215. where is the best place to buy the kit? while i had the carb off i took off the 4 screw cover just to see what it looked like and the diaphragm was intact but had some wrinkles/ stretched looking places in it, is that what a bad one looks like? i have never rebuilt a carb this small, but there is a guy with a video on youtube and it doesnt look too difficult. anything in particular to watch out for?

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Before you buy a kit check to see what a new carb cost. I have found that some carbs are 3 to 7 $ more than a carb rebuild kit.

@taxidermist:

yeah i paid 8 for the kit, and i saw some carbs for less than 20, but they are all from china and only look sort of like mine. i would be afraid the choke and throttle arms wouldnt fit correctly.i know some chinese knock offs are better than others. their china clone gy6 scooter motors are pretty good for instance. have you or anyone else actually bought one of these cheap chinese carbs and have they worked well?

well i got the carb kit today. i cleaned everything real well and matched the gaskets up. got it back together started it up and same thing. i let it run for about 10 minutes and it quit with a loud CLACK. now it wont even pull over by hand. could this be anything but a blown motor? i dont have much money in it but it would still be depressing as i put some time into it. maybe the previous owner ran it on straight gas or something. any thoughts?

unfortunately it could be the piston or rings if last owner didn't have oil in fuel, if so its best to buy a cylinder head and piston kit, and also bearing(s), if you have never done kind of work best to ask around for cost, but give time other members should be along soon to say what they feel about it.

i knowit could be the piston im just wondering if there is even a chance its not. could it be an exploded clutch or pull start malfunction?could it be a problem with the chain brake? on further examination when you shake the saw it sounds like a glass jar full of nails. how do i confirm a blown motor?

you can take off the chain and bar and then remove the pull starter (cord) with cover, remove plug, now see if you turn over the engine by hand.

well i took the pull starter and plug off and its trash. a bunch of black stuff that looked like fine sand came out of the plug hole, im guessing ground up rings. i guess this was probably my problem to begin with, low compression. im not really interested in rebuilding it, although thats probably an option. thanks for everybody's help.

Sorry to hear about the bad news, if you do go for a rebuild come back and let us know. The black stuff could just be carbon when you the time its worth taking the cylinder head off to have a better look at it you will then if its rings and piston.

Before you do all this carb work and stuff take two minutes and turn the high speed screw out 1 turn counterclockwise at a time and check after each adjustment. Saw is bogging down at full throttle because it is starving for fuel.
When I do this I start the saw, let it warm up for a minute or two, get my special adjustment tool ready and pull the trigger and rotate the high screw both ways and you will hear it bog when you go clockwise (in) shutting down fuel) then go counter clockwise till it revs and then starts sounding like a warble and come back till you find the best. Don't take too long doing this as it should only take 30 seconds of adjusting to find happy position at full throttle.
Hope this helps
Tom

Tom7461 said:

Before you do all this carb work and stuff take two minutes and turn the high speed screw out 1 turn counterclockwise at a time and check after each adjustment. Saw is bogging down at full throttle because it is starving for fuel.
When I do this I start the saw, let it warm up for a minute or two, get my special adjustment tool ready and pull the trigger and rotate the high screw both ways and you will hear it bog when you go clockwise (in) shutting down fuel) then go counter clockwise till it revs and then starts sounding like a warble and come back till you find the best. Don't take too long doing this as it should only take 30 seconds of adjusting to find happy position at full throttle.
Hope this helps
Tom

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HEY Tom .... Like some of us, you missed the posting date of this post, ( 2012 ) I do it as well as MANY of us do.. Don't worry, .. we'll laugh at ya AND with ya !! .. :laughing:...:thumbsup:

Let me see if this manual loads here.
View attachment ms210 manual.pdf