stihl 021 flywheel key

[tbyrd1960]

I have a mid 1990s Stihl 021. I recently disassembled; crank bearings seemed OK, installed new crank seals. Cleaned surfaces good and smeared thin film of rtv to embed new seals. New impulse and fuel lines. Problem was I broke the flywheel key when I was disassembling. Ordered a good used flywheel on ebay. When I got everything together and fired it up, the saw ran for about a minute then I heard something clanging. The flywheel nut had come loose and it broke the flywheel key again. After reading some other posts, I wonder if I over-torqued during assembly and broke the flywheel key without realizing it. I also was not aware of the need to completely degrease the tapered shaft and flywheel so not sure what, but I did something wrong. Pretty sure I am going to buy a new trim saw. I know others with more knowledge would fix this one, but I obviously would benefit from attending a Stihl school. Leaning toward buying a Echo CS-310 from my local hardware store for $200. My store has a 16" bar on the CS-310. I was looking for a 14 mainly because that is what the Stihl 021 came with and it serves my purpose. I know I am mixing 2 different topics, but what is the pro or con of a 14 inch bar on the Echo CS-310? Anyone out there want the 021 for parts?

 

[HarleyT]

Just take the saw and the old flywheel to a local saw shop, and have him put on the old flywheel for you with an impact wrench.

 

[tbyrd1960]

I have air compressor and impact wrench. I see where you are going. Clean up good to remove any oil or grease residue, align keyway for timing and tighten on tapered shaft with impact wrench.

 

[HarleyT]

Yeah, might use a sharpie to mark the slot, and just zip it on.
It likely wasn't torqued down enough before.

 

[tbyrd1960]

May be a couple of days, but will try this and let you know how it works out. Thanks

 

[HarleyT]

No blocking the piston, etc.

Leave the plug in.

 

[tbyrd1960]

I understand. Thanks

 

[Country bumpkin]

Yeah, might use a sharpie to mark the slot, and just zip it on.
It likely wasn't torqued down enough before.

I've seen that on a few also.

 

[tbyrd1960]

HarleyT thanks. I cleaned the shaft and flywheel bore using solvent to remove any oily residue. I used a sharpie to mark for keyway alignment, positioned the flywheel, tightened the nut by hand, then tightened it using the air wrench. Also rechecked the clutch nut on the other side. Saw fired up and ran very good. I had both air screws 1 turn out. At full throttle it sounds like it is a tad rich, but think I will leave it for now; see how it does under a load. I learned something on this one. Thanks for your help. I may get a few more years from this old 021.

 

[HarleyT]

Glad you got her goin'.....