free stihl 021 bogs down at wide open throttle

[cheapsaw]

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

 

[scott47429]

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

 

[cheapsaw]

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?

 

[scott47429]

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

 

[cheapsaw]

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?

 

[EngineMan]

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.

 

[taxidermist]

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

Rob

 

[cheapsaw]

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.

 

[cheapsaw]

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?

 

[EngineMan]

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.