Get a carburetor.
Stihl MS192 TC Bogs/Stalls when Cold
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Well, I just threw the new carb in it and unfortunately, it did not fix the problem. However, the saw did run much more relaibly with the new carb (was much harder to stall out and idled very well) but still had very sluggish acceleration and bog problems like before. I tried retuning and could not get reliable results, RPMs kept fluxuating on me and highs were creeping up to14k+ no matter where the H dial was. Plus idle RPMs were moving around a lot too between throttling up and restarts. Finally decided to try the carb cleaner trick one more time, sprayed one small jet right on the impulse line, near where it crosses the fuel lines (on the top of the saw) and the saw immediately died! I restarted it and tried again - same result! Holy crap, I'm excited, I hope it was just as simple as a gunky carb + leaking impulse line! I'm not sure why I couldn't really get it to die there before, but it's another cheap part to replace and the symptoms do seem to fit, so I guess I'm swapping that out next. . .
Well, I took off the impulse line while I was waiting for the replacement and decided to just do a ghetto pressure test on it using a bike pump, plug and soapy solution (I know, hardly professional) but I thought it might at least show off a bad leak. Well, I couldn't find any signs of a leak, at all. I'm starting to think the saw might have died with the carb cleaner because the intake vent for the fuel line is right above where I sprayed the carb cleaner (maybe the carb cleaner got sucked in enough to kill the engine?) There was an issue with the spring inside the impulse line - it was sort of folded over on itself, so I thought "maybe it's clogged up or something?" I uncrimped it and put everything back together. The saw has never run worse, haha. I think maybe in my tapping the crank shaft to get the flywheel off, I jostled the oil seal enough to make whatever air leak that was there even worse. Now when I tilt the saw side-to-side I get creeping revs in the idle. So, taking off the impulse line might have been a blessing in disguise because it may have helped me find the actual leak, haha. At any rate, I have some new oil seals on the way, I'm going to reseal the whole crank case and I'm still going to replace the impulse line too, just in case. I'll update again once all that is done!
Question regarding gasket makers, and I know there are a lot of opinions on this. But other than Dirko, I saw RTV high temp mentioned in this thread, so I ordered some a while back, thinking I might reseal the crank case. However, last night I was looking at the package and realized it explicitly states that it's "not recommended for use where in contact with gasoline" which is basically the crank case in a nutshell, haha. I saw some other posts about this and decided to order some Yamabond 4 instead, which sounds like should be fine/even better? One other thing, when greasing the oil seals, does it matter what grease is used? Can generic Oregon sproket grease work or just Husqvarna 2-stroke oil? I haven't been able to nail that one down, so any help would be appreciated!
Take the intake boot off and check it over very carefully, they pressure fit on the cylinder without a clamp using the plastic cover to secure it. They tear over time as the rubber anti vibe mounts stretch from flexing during hard use.
That's a good idea, I still think I'm gonna do a full reseal on this thing, given the last run's symptoms. But you never know, intake boot could be bad also, haha
Pressure test usually does not show a bad crank seal. Vacuum will. The complete reseal is a good idea. Testing first is better.
I went to permatex motoseal. It is for gasoline contact and metal to metal contact. You will get a bit of time from the RTV, but it will fail from experience.
Good to know, thanks for answering! you think Yamabond 4 is going to work also? Hoping so, because I already bought a tube, haha! Also, any thoughts on greasing the oil seals? Just 2-stroke oil good enough?
I use 2 cycle oil and a little paint brush to lube seals/bearings/rings etc during assembly 
If the Yamabond says gas resistant then it should work.
Alright, finally have an update:
I have some good news and some bad news, haha. The good news is, the saw definitely had a leak (or many leaks) and it now appears to be fixed after oil seal replacements and a new liquid gasket! The saw now holds a steady idle, does not bog or rev at all when tilted, etc. The old gasket looked flawless, however, so I can only guess it was the oil seals that were bad and/or the impulse line after I disconnected/reconnected it. Intake manifold looked perfect; flexable/rubbery and no signs of any cracking what-so-ever. Cylinder head was a little black, but rings were good and no signs of scoring or anything else wrong inside
The bad news is, I'm still having some acceleration problems (possibly just need to tweak carb settings more) and the saw is either overheating or burning bar oil, not sure exactly which.
Also, I ended up resealing the crank case 6 (that's right, 6) times before finally throwing in the towel and calling it 'good enough.' Maybe I'm just not cut out for this, but every. single. time. I meticulously tried to line up the oil seals perfectly with the outer edge of the crank case and every. single. time. the flywheel-side seal would magically suck in the bottom half right when I torqued the screws down their final quarter-turn - like magic! I tried all sorts of things, dry-fits, keeping the seal slightly proud before tightening, etc. Last (6th) attempt I came very close by pushing the seal in at the very end, but then again, I watched in horror as the seal slowly sucked itself in on the bottom again. I can only figure maybe there's some slight distortion on the crank case or something else, but I finally gave up and let the oil seal suck in slightly (I evened it out so it was perfectly straight) but I know the manual says to keep them flush, so I'm not super happy about it. I'm hoping it's not the end of the world, but if someone on here knows otherwise, please let me know. Perhaps then I'll need to do it a 7th time with a new crank case bottom or something.
Moving back to the overheating/smoking issue. . .I can't say for certain, but I'm pretty sure the smoke coming off the saw is white and only on the muffler side. When I first ran the saw after the reseal, I thought I saw some blueish smoke coming off both the muffler-side and the fly-wheel side, which freaked me out, so I shut it off. After a few minutes of cooling off, I fired it back up and did not see the blue smoke again, which makes me think maybe it was residual liquid gasket/gunk burning off - is that something that can happen? At any rate, assuming that isn't an issue, the white smoke on the bar-side makes me think that maybe the bar oil is leaking out of a bad hose and spraying all over the muffler rather than going to the bar. Does anyone have any experience with these kinds of issues, is there anything I could test that would clarify what I'm seeing? I peeked at the oil tank after running the saw for 5 minutes and it looked lighter brown, which seemed odd to me, but maybe that's normal? I'm also running Husqvarna bar oil in it, I can't imagine it's a problem though, is it? Feeling a bit disappointed after going through all of that, but I guess I'm glad the saw actually ran after everything I did to it, haha. Looking for tips/suggestions on where to go next from here, if anyone has any insight. As always, I really appreciate it!
I have some good news and some bad news, haha. The good news is, the saw definitely had a leak (or many leaks) and it now appears to be fixed after oil seal replacements and a new liquid gasket! The saw now holds a steady idle, does not bog or rev at all when tilted, etc. The old gasket looked flawless, however, so I can only guess it was the oil seals that were bad and/or the impulse line after I disconnected/reconnected it. Intake manifold looked perfect; flexable/rubbery and no signs of any cracking what-so-ever. Cylinder head was a little black, but rings were good and no signs of scoring or anything else wrong inside
The bad news is, I'm still having some acceleration problems (possibly just need to tweak carb settings more) and the saw is either overheating or burning bar oil, not sure exactly which.
Also, I ended up resealing the crank case 6 (that's right, 6) times before finally throwing in the towel and calling it 'good enough.' Maybe I'm just not cut out for this, but every. single. time. I meticulously tried to line up the oil seals perfectly with the outer edge of the crank case and every. single. time. the flywheel-side seal would magically suck in the bottom half right when I torqued the screws down their final quarter-turn - like magic! I tried all sorts of things, dry-fits, keeping the seal slightly proud before tightening, etc. Last (6th) attempt I came very close by pushing the seal in at the very end, but then again, I watched in horror as the seal slowly sucked itself in on the bottom again. I can only figure maybe there's some slight distortion on the crank case or something else, but I finally gave up and let the oil seal suck in slightly (I evened it out so it was perfectly straight) but I know the manual says to keep them flush, so I'm not super happy about it. I'm hoping it's not the end of the world, but if someone on here knows otherwise, please let me know. Perhaps then I'll need to do it a 7th time with a new crank case bottom or something.
Moving back to the overheating/smoking issue. . .I can't say for certain, but I'm pretty sure the smoke coming off the saw is white and only on the muffler side. When I first ran the saw after the reseal, I thought I saw some blueish smoke coming off both the muffler-side and the fly-wheel side, which freaked me out, so I shut it off. After a few minutes of cooling off, I fired it back up and did not see the blue smoke again, which makes me think maybe it was residual liquid gasket/gunk burning off - is that something that can happen? At any rate, assuming that isn't an issue, the white smoke on the bar-side makes me think that maybe the bar oil is leaking out of a bad hose and spraying all over the muffler rather than going to the bar. Does anyone have any experience with these kinds of issues, is there anything I could test that would clarify what I'm seeing? I peeked at the oil tank after running the saw for 5 minutes and it looked lighter brown, which seemed odd to me, but maybe that's normal? I'm also running Husqvarna bar oil in it, I can't imagine it's a problem though, is it? Feeling a bit disappointed after going through all of that, but I guess I'm glad the saw actually ran after everything I did to it, haha. Looking for tips/suggestions on where to go next from here, if anyone has any insight. As always, I really appreciate it!
First and foremost, the oil seals just have to be close, not perfect. Second, if you used any sort of lube while re-assembling the saw (and I hope you did) the smoke was probably the extra oil burning off. All my fresh rebuilds blow a little smoke when I first fire them up and provided it doesn’t persist it’s not an issue.
yes I lubed up the oil seals on the inside with 2-stroke oil, so maybe that was it! Thanks for the info, I'll keep an eye on the smoke color next time I fire it up to be sure. Also, great to hear on the oil seal placement, hopefully I got "close" enough, haha.
Got a chance to do some more diagnosing tonight. I started with taking a closer look at the "new" carb I got for the saw. I bought it online, so 'buyer beware' I know, but it appears to be a genuine Yama, etc. When I took the covers off, the diaphragm seemed kind of stiff and the gasket was junk and fused to the main body of the carb. It took quite a while to scrape all the gunk/residue off but after I did, I replaced the gasket/diaphragm and the gasket/sheet on the other end as well. So, the carb may have been 'new' but maybe, sitting on a shelf for 5 years 'new' or something. Once I got it all back together, I took off the chain, bar & cover and fired it up. I had to do some heavy adjustments to the L and Idle jets to get the saw to even idle, but after that it seemed snappy and responsive for once, which was encouraging. I watched carefully when the saw was revving and could definitely see bar oil coming out of the oil pump connector, where it's supposed to come from, but also from behind the bar tensioner slide - is that normal? I didn't see any egregious amounts of oil spraying onto the exhaust to cause a smoke issue, but a lot was pooling under the saw as it seeped down (to be expected of course). I wonder if just the amount of oil coming off the saw + the bar cover is funneling excess oil onto the exhaust and/or engine cooling fins. At this point, I'm not really sure what is wrong because at least from a functional stand-point, it seems to be working as intended. A little bit of good news, there was no blue smoke this time, so it seems likely it was just excess 2-stroke from the oil seals burning off!
Uncertain if there was anything actually wrong with the oil pump or any leaks in it's connectors, I decided to put the whole saw back together and fire it up one more time. Much to my dismay, the saw bogged immediately and once again I had to noodle with the L jet just to get it to rev. I was able to hit higher RPMs this time, but it still felt kind of sluggish to me on the acceleration. At this point, I'm not really sure what else to do, I think I'll try tuning it again tomorrow just to see if it gets me anywhere, but I can't really seem to get it to work the way it seems like it should. Does anyone have any other ideas? Feeling a bit stuck here and it's frustrating because I also feel like I'm really close to bringing this saw back to life. . .
Uncertain if there was anything actually wrong with the oil pump or any leaks in it's connectors, I decided to put the whole saw back together and fire it up one more time. Much to my dismay, the saw bogged immediately and once again I had to noodle with the L jet just to get it to rev. I was able to hit higher RPMs this time, but it still felt kind of sluggish to me on the acceleration. At this point, I'm not really sure what else to do, I think I'll try tuning it again tomorrow just to see if it gets me anywhere, but I can't really seem to get it to work the way it seems like it should. Does anyone have any other ideas? Feeling a bit stuck here and it's frustrating because I also feel like I'm really close to bringing this saw back to life. . .
with the bar and chain on can you easily move the chain on the bar?
yes, slides easily. I was re-reading the manual again last night and I realized I was tuning the carb incorrectly, so I'm going to try it again and hope that does the trick. As for the oil burning on the exhaust/engine fins, still looking for suggestions here!
It's likely from you taking it apart, cleaning it, touching it and getting oil (you can not see) all over it during cleaning. It may smoke for a few minutes after a teardown, it may smoke a second time and have smoke coming off the cylinder once you get it good and hot from working it hard cutting. I've had a few smoke like a tar kettle after removing loads of packed on oily sawdust/sap/dirt etc...even more have had smoky mufflers. Remember we adjust idle (low jet) speed when cold then adjust high speed when fully warm. I think you need to get a tach and follow the work shop manual to the T on setting the carb adjustments. The adjustment listed on the cover for 1-1/2 turns out is a base line to start from pending the idle set screw is correctly set. The tach becomes invaluable on saws that the carb has been fiddled with by everyone in town....start from the beginning.
Any time I take a clamshell apart here It gets brand new crank seals and rings and very often a new wrist pin, since they are a pta and I want nothing to do with taking it back apart, removing sealant, cleaning it of any and all oils then fighting it back together quickly because the sealant dries fast. The one step I do thats not mentioned anywhere is once assembled I do not fully tighten the cylinder bolts fully at first, just barely tight to allow the sealant to partially start setting up for about 5 minutes then I finish tightening. If you use too much sealant you will have slivers of it come off inside the engine. When you run the engine does it spit fuel out of the carb with the air filter removed at full throttle?
Any time I take a clamshell apart here It gets brand new crank seals and rings and very often a new wrist pin, since they are a pta and I want nothing to do with taking it back apart, removing sealant, cleaning it of any and all oils then fighting it back together quickly because the sealant dries fast. The one step I do thats not mentioned anywhere is once assembled I do not fully tighten the cylinder bolts fully at first, just barely tight to allow the sealant to partially start setting up for about 5 minutes then I finish tightening. If you use too much sealant you will have slivers of it come off inside the engine. When you run the engine does it spit fuel out of the carb with the air filter removed at full throttle?
Interesting, yeah I did not see this mentioned anywhere. I didn't really do this, but as I was super slow/careful trying to get the oil ring to sit right, I may have actually had a similar time-frame for fully tightening the screws down. I'll have to try taking the filter off and report back later for the spraying gas question.
As for the carb tuning, I do have a tach (the cheap kind with the cord that wraps around the spark plug) but I had mixed up a step in my head for the tuning process, so I was doing it all wrong. I'm gonna take another stab at it next chance I get, so I'll let you know how that goes.
As for the white bar oil smoke, that's good to know. . .I honestly didn't get much smoke at all last night in my tests, but it was also sitting on a relatively flat surface, so the oil was just ending up under the saw. I do wonder if maybe it won't be a problem once I'm actually cutting/using it, rather than just revving it to test RPMs and tuning. Anyway, hope the re-tune does the trick. As always, thanks for the info/advice!
