echo cs-520 advise

[david newbie]

I came across a nice looking 520 on ebay with bar and chain. I was hoping I could simply do a carb rebuild, but I discovered it has a very scored piston. Any ideas where to get a decent piston? I'm mostly seeing Little Red Barn. I imagine I should replace the seals as well? Has anyone found a good reasonably priced source? Any other tips? Ive heard that I need to open up the muffler. Ive got it mostly torn down now, just hope I can remember how to put it back together. Also, I'm coming up with several part numbers for the piston and not sure which is correct. P021006150 (NA) ,P021006152, P021006153. Any ideas?

 

[Marley5]

I'm almost certain it's P021006153.
As I'm almost certain the CS 510, 520 and 530 use the same piston.
Amazon has been my source for years for OEM.
I do a muffler mod on every saw I buy but a re-tune is required afterwards.

 

[david newbie]

I'm almost certain it's P021006153.
As I'm almost certain the CS 510, 520 and 530 use the same piston.
Amazon has been my source for years for OEM.
I do a muffler mod on every saw I buy but a re-tune is required afterwards.

Is there a trick to pulling the oil pump? I think I have to remove it to pull the cylinder??

 

[david newbie]

Still can’t pull the oil pump or the cylinder. I must be missing a step. Does the wall between cylinder and carb simply lift off with the cylinder. I’m stuck

 

[Marley5]

You have to pull the oil pump drive gear from the crankshaft before removing the oil pump.

 

[david newbie]

Does that washer/wurm drive spin Off or lift off?

 

[david newbie]

The center circle of that washer seems totally stuck to the crankshaft. Will I melt any thing if I put a small torch on the washer?

 

[david newbie]

Any more thoughts? I'm pretty much stcu on pulling the cylinder until I get that washer off. Prying with a fine tipped screwdriver does not seem to break it free from the crankshaft.

 

[Cliff R]

Since it's a "clam-shell" I'd try to locate a complete engine assembly and swap it out. You're going to get your feelings hurt splitting the case and trying to clean up the cylinder well enough to replace the piston and rings.....FWIW.....

 

[mountainlake]

https://www.sepw.com/cart.php $49 Steve

 

[david newbie]

Since it's a "clam-shell" I'd try to locate a complete engine assembly and swap it out. You're going to get your feelings hurt splitting the case and trying to clean up the cylinder well enough to replace the piston and rings.....FWIW.....

Unfortunately, that’s NLA. Don’t have to split the case on this saw any way. Just need to remove the oil pump

 

[david newbie]

Hard to believe that I’m the only guy on this forum that ever tried to do this on this model before

 

[telecasterfool]

Have you unbolted that pump?

 

[telecasterfool]

I've done it...

 

[david newbie]

Yes the pump was unblolted when I made my attempts. I just put the screws back in so I wouldn’t lose them. So , am I correct in thinking I have to remove the washer/worm drive first to pry the pump off? It’s really stuck to the crank. Does it lift off or spin off?

 

[turkeybob]

Yes the pump was unblolted when I made my attempts. I just put the screws back in so I wouldn’t lose them. So , am I correct in thinking I have to remove the washer/worm drive first to pry the pump off? It’s really stuck to the crank. Does it lift off or spin off?

Post for service manual in the 'post for manuals' thread, it will help you to understand the way to repair the saw

 

[Cliff R]

I've owned several CS-510's and one CS-520 and they are all "clam-shell" engines. This requires splitting the case to remove the piston.....

https://www.ebay.com/itm/1330176859...mAZTPE6TQisFSaOH9H0xsrRYgQ==|tkp:BFBM4vra-Odk

 

[telecasterfool]

Cliff - I believe the clamshell engine can actually be removed entirely from the base of the saw. https://www.partstree.com/models/cs...999/engine-short-block-sb1080-engine-cover-5/

The oiler work gear is a press fit on to the crank. It can be GENTLY heated and GENTLY removed with a puller. Putting a cold rag on the crank helps it to shrink while the work gear is expanding... maybe someone else will have a better technique...

 

[Cliff R]

Yes, the engine is easily removed from the "cradle" then it has to be split to get to the piston and cylinder....

 

[telecasterfool]

David newbie - I purchased a very nice 520 with a scored cylinder. I found a nice used "short block" and bolted that into mine. you can still buy the short block new, but it's probably more than you want to spend.