038 super top end rebuild

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KarlD

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D633411E-728E-431C-BFD3-094E1FF1F98D.jpeg D633411E-728E-431C-BFD3-094E1FF1F98D.jpeg Morning guys. I’m going to put a new top end on this saw and was wondering if anyone has a recommendation for which piston and cylinder I should buy; plenty on eBay and genuine are mega money...anybody done this and can recommend a pair? Thanks in advance
 
Done a few, I assume it’s scored up or straight gassed?

Used or new OEM Stihl cylinder, but first see if yours cleans up.

New OEM piston & circlips, or a meteor piston & rings & OEM circlips.

New OEM wrist pin bearing.

About a $250 saw, so I understand it’s hard to justify “mega money”, but you get what you pay for! Avoid all the Chinee parts for that old workhorse.
 
Thank you, good leads there. I’ll put up some pics of the cylinder and piston and get a compression reading
 
Have a good parts saw with a good 50mm top end you need. Good compression
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Sent from my iPhone using Tapatalk
 
Have a good parts saw with a good 50mm top end you need. Good compression
53d58676906b821fee7a062dee45f45c.jpg
ad07acd272f1ca061545b716f0e19055.jpg
36c8d65731633c6aaf7f38b6e2dc9e2b.jpg



Sent from my iPhone using Tapatalk

Ok thank you. I’ll have a better look at mine (it was put away years ago and iirc it was low on compression) but I’ll have another look and post pics. Will u want to sell the whole saw or just the top end? Shipping from the us to uk might be ££££
 
I had an hour spare today so here's a video showing the damaged piston/rings and a pic of the low compression (80psi)

IMG_E0240.JPG
 
Have a good parts saw with a good 50mm top end you need. Good compression
53d58676906b821fee7a062dee45f45c.jpg
ad07acd272f1ca061545b716f0e19055.jpg
36c8d65731633c6aaf7f38b6e2dc9e2b.jpg



Sent from my iPhone using Tapatalk

Kyle...will you send me just the top end and if so how much? It would need shipping to the UK though so it might be too much hassle and or not cost effective?
 
So the rain over here has meant a slack week, so I’ve started to strip the saw. No problems until now...I cannot remove one end of the brake band from the body of the saw. It locates over an aluminium? stub, and it looks to definitely sit under an edge/shelf; I assume the stub should be removed to allow removal of the band. It is not slotted or anything tho (and I cannot pull it out) so I’m a bit stumped?
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Any ideas guys?
Thanks in advance :sweet:
 
Scrub that, just done it. Grabbed it with the mole grips and twisted it out. Seems very un-Stihl like to me; maybe a new stub is supplied with a new brake band :wtf:
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It’s going well, I’m ready to split the crank case now. I’ll save that for tomorrow. I think the cylinder could be refurbished but I’m going to fit a new P&C because I want to.

Can I make this 038S into a Magnum or is the case different between the models? I only ask because I might as well build the ultimate if I can :chainsaw:
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I have searched and found the answer; the crank cases differ between 038/038S and 038mag/038mag2 but nothing that a bit of fettling can’t overcome. So, now to try to find a magnum top end...
 
I’ve changed my mind again lol, I’m going to clean up the cylinder and fit a new 50mm piston. I hate wasting a well engineered component so instead of going 52mm I will make my first attempt at improving the existing cylinder. What do I do, widen the port to match the gasket and then polish it smooth?
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Anything else, bearing in mind it is my first and I’m just going to use a Dremel free hand?

The port is tapered, it widens from piston to exhaust...should I maintain this taper or something else?

Thanks in advance :cheers:
 
Only need to widen port to match muffler, or vice/versa. Unless you are going to do port work too.

The 038M ex ports are wider, and 038S mufflers don't match up, unless you grind them.

For ex clean all that carbon out and give it a polish.
 
Thanks for the advice...this is the same gasket on the muffler
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...so I should widen the cylinder exhaust port to match the gasket/muffler?

Finishing with removing all of the carbon and polishing and doing an appropriate muffler mod.

Thanks for your time :cheers:
 
Could use gasket as a template, scribe both, then match them up.

I don't remove inner baffle on muffler, some do. I drill a few 3/8"/14mm holes in it. On dual port mufflers I open up outlets as large as the screens allow.

Setting cylinder squish to ~0.020" will also help and not hard to do.
 
Great, thank you. I was planning on measuring and if necessary adjusting the squish. I can’t believe how restrictive the muffler looks...
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...why would they (pre EPA)compromise the performance of the saw to this extent?
 
a good runnin s is not far behind a m.
bury 24"+ then you'll see more diff.
i prefer bing carbs on either.
recently got a s w/tilly, a first here. others were zama or bing.
might try a bing, tho the tilly one is pretty good so far.
 
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