Thunderhead
ArboristSite Lurker
Ok, thanks for the feedback!
Stihl MS200 bogs down at throttle
- Thread starter Thunderhead
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There is a big issue there without question. It’s an air leak and must be fixed. Also, I personally wouldn’t have that mechanic fiddle with your saws again.
Its best to pressure and vac test it before tear down, determine where the air leak is if there is one by spraying soapy water around all joints, any one can be the culprit. The radial seals can be a pain to replace for the beginner, if needed to replace them it may be best to have them done by a shop with a good reputation.
Thunderhead
ArboristSite Lurker
Sorry to burden you all, but I'm getting conflicting information. I just called a shop not too far from here who sells and do service on all types of small engines. They have been around for longer than I can remember and has a very good reputation in the area. The man I talked to agreed the L and LA screws where not adjusted correctly, but also said that if the saw had an air leak, it would be close to impossible to make it run smooth on idle.
And just to clarify, the saw now starts normally, runs at idle just fine, revs good with no hesitation and I've just been out and made a few cuts with it, and all felt normal...
And just to clarify, the saw now starts normally, runs at idle just fine, revs good with no hesitation and I've just been out and made a few cuts with it, and all felt normal...
Nathan Graff
ArboristSite Operative
I"d listen to lonewolf. He's torn down, fixed, and rebuilt more of the ms200s that anyone else I know of.Sorry to burden you all, but I'm getting conflicting information. I just called a shop not too far from here who sells and do service on all types of small engines. They have been around for longer than I can remember and has a very good reputation in the area. The man I talked to agreed the L and LA screws where not adjusted correctly, but also said that if the saw had an air leak, it would be close to impossible to make it run smooth on idle.
And just to clarify, the saw now starts normally, runs at idle just fine, revs good with no hesitation and I've just been out and made a few cuts with it, and all felt normal...
If that is the case then why was the L screw backed out 5 turns? At 5 turns out that is a lot of raw fuel entering the crankcase, usually done to mask an air leak.Sorry to burden you all, but I'm getting conflicting information. I just called a shop not too far from here who sells and do service on all types of small engines. They have been around for longer than I can remember and has a very good reputation in the area. The man I talked to agreed the L and LA screws where not adjusted correctly, but also said that if the saw had an air leak, it would be close to impossible to make it run smooth on idle.
And just to clarify, the saw now starts normally, runs at idle just fine, revs good with no hesitation and I've just been out and made a few cuts with it, and all felt normal...
OP, there is probably over 60 years of joint chainsaw experience from the chaps just on your thread. If they say it needs to be vac tested and fixed, trust them The leak will worsen and you’ll cook your saw.
Air leaks differ, some are small and can be tuned out (though this is never the answer - it’s a band aid on the issue) these ones will allow your saw to run fine like like yours is, others you can’t tune out.
The fact that you are 5 turns out on the low, it’s not falling flat on its face, it actually can run on that and it’s not smoking the neighbourhood out says there is much more air involved than there should be. That air isn’t coming from the Venturi, and the only air entering the saw should be through the Venturi.
Your saw has problems and you are in the right place to fix it. You’ll get help from everyone. First go back to the chainsaw sub forum and find the very first thread “chainsaw stickies”
In there look for “beg for manuals”
In there put a post up asking for an IPL and service manual for your saw.
Then go on to EBay and get a pressure AND vacuum tester.
Then come back
The leak will worsen and you’ll cook your saw.Air leaks differ, some are small and can be tuned out (though this is never the answer - it’s a band aid on the issue) these ones will allow your saw to run fine like like yours is, others you can’t tune out.
The fact that you are 5 turns out on the low, it’s not falling flat on its face, it actually can run on that and it’s not smoking the neighbourhood out says there is much more air involved than there should be. That air isn’t coming from the Venturi, and the only air entering the saw should be through the Venturi.
Your saw has problems and you are in the right place to fix it. You’ll get help from everyone. First go back to the chainsaw sub forum and find the very first thread “chainsaw stickies”
In there look for “beg for manuals”
In there put a post up asking for an IPL and service manual for your saw.
Then go on to EBay and get a pressure AND vacuum tester.
Then come back
Definitely has an air leak and use will kill your saw. Maybe send it to lonewolf, he is the master of all things Ms200, if he has the time he will definitely be the best to do it and likely not that much more expensive than the other options. If he had the time. Just my 2p
Sorry to burden you all, but I'm getting conflicting information. I just called a shop not too far from here who sells and do service on all types of small engines. They have been around for longer than I can remember and has a very good reputation in the area. The man I talked to agreed the L and LA screws where not adjusted correctly, but also said that if the saw had an air leak, it would be close to impossible to make it run smooth on idle.
And just to clarify, the saw now starts normally, runs at idle just fine, revs good with no hesitation and I've just been out and made a few cuts with it, and all felt normal...
I agree with your service guy that in case of a significant air leak, it will be almost impossible to tune it to idle correctly, regardless of how many turns out. I'd say if your saw is running the way you describe now, I think it's safe to run it. The confusion is all about the number of turns out you confirmed....that's way out of standard setting. But with chinese stuff , you never know for sure.
There is no set amount of turns out for LA ! It is the idle stop screw basically . If you have an OEM carb on there and the L is adjusted 5 turns out and your shop agrees with this they are sorely mistaken !Sorry to burden you all, but I'm getting conflicting information. I just called a shop not too far from here who sells and do service on all types of small engines. They have been around for longer than I can remember and has a very good reputation in the area. The man I talked to agreed the L and LA screws where not adjusted correctly, but also said that if the saw had an air leak, it would be close to impossible to make it run smooth on idle.
And just to clarify, the saw now starts normally, runs at idle just fine, revs good with no hesitation and I've just been out and made a few cuts with it, and all felt normal...
Ultimately OP, you do what you feel most comfortable with. If you run it though, you are going to cook that saw sooner or later and that would be a big shame.
Think logically. You took the saw out one day, and all of a sudden it didn’t work how it did last time. That in itself says, something isn’t right.
You wonder, maybe it’s hard diaphragms, fuel line, filter, etc,
All possibilities. Yet you change them all with no improvement.
Then think ok, well it’s lean, that means it’s either too much air to fuel or too little fuel to air.
Well you know that the fuel is getting to the carb and to the engine and you have tried giving it as much fuel as the factory will let you with limiters. They are there to give you a range to work in if the saw is performing ok. Certain times like old diaphrams, that then don’t pump as much fuel, benefit from being able to pass the limit of the caps, but never 5 turns and you put a new carb on anyway.
The only rational thing to think next is that there is more air entering somewhere.
That’s the only route you haven’t taken yet, and it’s a shame you won’t invest a few dollars on a pressure and vac tester but you did with all the Chinese parts that haven’t helped.
You have to decide, but it’s a saw with sentimental value and your repair bill is going to be big when you cook it.
Think logically. You took the saw out one day, and all of a sudden it didn’t work how it did last time. That in itself says, something isn’t right.
You wonder, maybe it’s hard diaphragms, fuel line, filter, etc,
All possibilities. Yet you change them all with no improvement.
Then think ok, well it’s lean, that means it’s either too much air to fuel or too little fuel to air.
Well you know that the fuel is getting to the carb and to the engine and you have tried giving it as much fuel as the factory will let you with limiters. They are there to give you a range to work in if the saw is performing ok. Certain times like old diaphrams, that then don’t pump as much fuel, benefit from being able to pass the limit of the caps, but never 5 turns and you put a new carb on anyway.
The only rational thing to think next is that there is more air entering somewhere.
That’s the only route you haven’t taken yet, and it’s a shame you won’t invest a few dollars on a pressure and vac tester but you did with all the Chinese parts that haven’t helped.
You have to decide, but it’s a saw with sentimental value and your repair bill is going to be big when you cook it.
Thunderhead
ArboristSite Lurker
I went to a local shop today and did both the pressure and vacuum test on the saw. We hold the pressure/vac for about a minute, no movement what so ever on the needle, and on pressure, no bubbles from the soapy water. The saw was sealed between the cylinder and muffler and I put a 1/2 inch extender in the rubber intake manifold to seal that one off. The only, and last place to look, will be between the carb and intake manifold, but also this one looks clean and in good shape.
Curiouser and curiouser as the cat said....
Curiouser and curiouser as the cat said....
The carb set to 5 turns out, is that OEM?
Did you rotate the crank during the vacuum test? If you don’t spin the crank it will often hold vacuum at the crank seals even with a leak.
Yes all mating surfaces must be checked. To confirm, you checked the Intake manifold fully for leaks? You can’t bung a manifold with anything (like a 1/2” adapter) because you will possibly seal a small crack. It must be in place on the saw.
As another guy said, Lonewolf has a reputation for knowing these saws better than most anyone. He’ll be back. I guarantee though, every person that reads this post and sees 5 turns out on an OEM carb with a good kit and the other parts replaced as you say, will tell you the same, it’s got a fuel / air issue. 5 turns out is about as obvious of an issue as you can get IF it’s your OEM carb and the diaphragms are good.
If the carb that is set to 5 turns out isn’t OEM. As said earlier, put the OEM one back on and have it tuned properly. Chinese carbs are a liability.
Diaphragms harden with ethanol and can stretch with normal fuel with age. Heck if the gaskets and diaphrams
In the Chinese look better than your OEM (only if they look bad and are hard) then put them in and try.
Did you rotate the crank during the vacuum test? If you don’t spin the crank it will often hold vacuum at the crank seals even with a leak.
Yes all mating surfaces must be checked. To confirm, you checked the Intake manifold fully for leaks? You can’t bung a manifold with anything (like a 1/2” adapter) because you will possibly seal a small crack. It must be in place on the saw.
As another guy said, Lonewolf has a reputation for knowing these saws better than most anyone. He’ll be back. I guarantee though, every person that reads this post and sees 5 turns out on an OEM carb with a good kit and the other parts replaced as you say, will tell you the same, it’s got a fuel / air issue. 5 turns out is about as obvious of an issue as you can get IF it’s your OEM carb and the diaphragms are good.
If the carb that is set to 5 turns out isn’t OEM. As said earlier, put the OEM one back on and have it tuned properly. Chinese carbs are a liability.
Diaphragms harden with ethanol and can stretch with normal fuel with age. Heck if the gaskets and diaphrams
In the Chinese look better than your OEM (only if they look bad and are hard) then put them in and try.
OP, is it in fact a new OEM carb or used? Go and turn both of the H and L screws back to the factrory setting at 1 turn out ea and tell us what happens.
5 turns out on the "L" screw? With an OEM carb if the screw is out more than about 2 and 1/2 turns it's not adjusting anything and it shouldn't make any difference to go to 5 turns where it is about ready to fall out of the carb. A mechanic left it at that?
Thunderhead
ArboristSite Lurker
I appreciate the replies, thanks a lot!
The carb is the oem that came with the saw, the china carb hasn't been on the saw for months. Will put the saw back together in the afternoon and try to adjust the carb back to basic settings and see what happens.
Btw, the crank was rotated while pressure/vac test.
The carb is the oem that came with the saw, the china carb hasn't been on the saw for months. Will put the saw back together in the afternoon and try to adjust the carb back to basic settings and see what happens.
Btw, the crank was rotated while pressure/vac test.
Sounds like a bad carb based on your vac test . Forget China aftermarket junk ! Can you send me a pic of the side of the OEM carb that on the air filter side so can see if it has an accelerator pump? Can you get a rebuild kit for that OEM carb and clean it? Buy a new one OEM if all else fails.
Thunderhead
ArboristSite Lurker
Quick temporarily update.
I've assembled the saw and had just a couple of minutes to play with it because dinner was ready. The saw started fine and run smoothly on idle, and also revved without hesitation. Then I started to turn the L screw in. Nothing happened the first couple of turns or so, then idle increased and I adjusted it down with LA a few times until I've come to where I guessed it was about one turn left, then I just quickly turned it all the way in and the saw stopped. Then I took the L screw about 1 full turn out and it started on first try and run fine on idle (H screw was not touched). I do more testes and maybe some cuts in the evening and give an update in a few hours.
I've assembled the saw and had just a couple of minutes to play with it because dinner was ready. The saw started fine and run smoothly on idle, and also revved without hesitation. Then I started to turn the L screw in. Nothing happened the first couple of turns or so, then idle increased and I adjusted it down with LA a few times until I've come to where I guessed it was about one turn left, then I just quickly turned it all the way in and the saw stopped. Then I took the L screw about 1 full turn out and it started on first try and run fine on idle (H screw was not touched). I do more testes and maybe some cuts in the evening and give an update in a few hours.
Put both at one out so I know if its running right where it is supposed to be.
