I was recently given a stihl 025 with a high idle. to which Iam unable to adjust the carb, to slow down the saw, so I'm thinking air leak. I'am going to tear down this saw to look for possible air leaks. So there are many different sealers to chose from. I am interested to see what is your favorite, and why? What brand will you never use again, and why?
So if we're talking base gasket delete/cylinder to case sealer, I've use Motoseal for a while with great results. It's a dead ringer for Hondabond. If you were given the 2 with blank labels, you'd never know the difference.
Being as though it is an 025 there is no base gasket. It is a clamshell, Stihl uses Dirko at the factory as I recall, but most engine sealers will work. Motoseal, Threebond, Hondabond, Yamabond and I am sure there are some I missed.
On a two-cycle, the sealant must be fuel-resistant in addition to being oil resistant. Anything sold for use on two-stroke ATVs will work fine. I do like Dirko, as it's not hard to get and it was the original sealant used for years. Plus, who doesn't love the questioning looks when your hands, shirt, and workbench look like a murder scene? Stihl used to sell seals for the clamshells that didn't require disassembling the engine. Do they not anymore?
Could the OP also be interested in crank seals? I think that’s a more likely leak than cylinder But what I’ve found on a few clam shells, including an 025, that the cylinder bolts need to be tightened Some, maybe not all, are accessible without pulling the tank. I’d try getting a turn on those first before tearing it down
This is the underside of an MS 250, actually 2 different ones. top one has the handle bar mount removed and access to the 4 cylinder bolts is easy. the second pic has the handle bar mount still on, and access is a little tougher. I still would try getting a turn on these and see how that works out before doing too much more. Replacing seals or sealant, you have to get to these bolts anyway.
