Stihl MS260 rebuild - Meteor Piston and Cylinder Kit

Keepfixin · May 01, 2024, 05:15:43 AM

Another saw getting worked on! This one was unfortunately straight gassed. In good shape otherwise. Bought a meteor kit for it. Been waiting 17 years to finally buy one of these kits!! Thought I would share some pictures. It has some rough castings and also not the smoothest exhaust port.

Keepfixin · May 01, 2024, 05:17:45 AM

Piston pictures. It's also domed.

Keepfixin · May 07, 2024, 02:40:38 PM

Opened up the piston ports, cleaned up the casting marks on cylinder, and also smoothed up exhaust port roughness. Piston lost 1.1 grams with modifications. Wasn't going to but watched tinmans saws on YouTube and everything just seemed like it needed some dressing up then :-). Piston work is experimental but exhaust needed done and also the cooling fins needed cleaned up. Seen a lot of saw cylinders with rough castings in the fins and all that does is lead to sawdust and pitch hanging up and accumulating then possibly a saw overheating.

Keepfixin · May 09, 2024, 11:09:51 PM

Well got the "the duke's" bearing set in. Mag side bearing feels a little rough and PTO side bearing was a polyamide cage bearing instead of a metal cage bearing showed in the ebay picture :-/. Good thing I ordered a Koyo 16002 for the Mag side bearing. Koyo's spin real smooth! Also stopped by the local Stihl shop and just picked up a Stihl PTO bearing. It has a polyamide cage bearing also but at least I know the saw is going to have quality bearings in it.
First pic: All 4 bearings
Second pic: the duke bearings
Third pic : Duke left and Stihl right- seal side
Fourth pic: Duke left and Stihl right- crank side
The Stihl bearing looks like it has a slightly thicker inner race surface.

Keepfixin · May 09, 2024, 11:34:01 PM

Just measured the inner race on the Mag side bearings. Koyo 2.72mm and the dukes bearing 2.5mm.

DHansen · May 10, 2024, 09:18:55 PM

Does the Sthil brand have one extra roller ball in each bearing compared to the aftermarket? Looking at the fourth photo in post #3.

Keepfixin · May 11, 2024, 03:18:17 AM

Yes it does have an extra roller! 9 compared to 8. Good eye. I missed that!
Saw has 150 psi compression and had .022" squish in the top end at the top of stroke.
Upper ring end gap - .008"
Lower ring end gap- .009"