Idle issues Stihl MS271 HELP

[Sparky 46]

Help, my Stihl MS271 won't idle and dies at idle. New Carb, fuel filter, cleaned muffler,no ethanol fuel only, tried adjusting. Rebuilt the original Carb. and tried that with no luck and exactly the same outcome as the new carb. No matter what we do it simply dies when it goes back to idle. What am I and my friend missing, we are stumped. We are both fix anything for everyone mechanics and stumped. My first time posting here and happy to join this community, Thank you all !!!

 

[Sparky 46]

Help, my Stihl MS271 won't idle and dies at idle. New Carb, fuel filter, cleaned muffler,no ethanol fuel only, tried adjusting. Rebuilt the original Carb. and tried that with no luck and exactly the same outcome as the new carb. No matter what we do it simply dies when it goes back to idle. What am I and my friend missing, we are stumped. We are both fix anything for everyone mechanics and stumped. My first time posting here and happy to join this community, Thank you all !!!

I should add it's not a new saw but has relatively low hours and never seen ethanol fuel. Not rode hard and put away wet. Thanks

 

[hacskaroly]

my Stihl MS271 won't idle and dies at idle.

Welcome to the forums! Possibly an air leak between the carb and cylinder or either of the oil seals. You can get the saw running and then spray non-flammable brake cleaner around those areas, and if there is a leak then the saw will shut down (with no damage), though you could also use (but I don't recommend) carb cleaner which is flammable and if there is a leak, the saw will race - not the greatest thing. Either way you will know if you have an air leak.

Also, the on/off/choke lever is easy to bend if you (or the previous owner) wrench on it, possible that when blipping the trigger it actually connects the contacts to shut it off. I had to replace one of mine because of that.

 

[Agent Smith]

Another thing to check is the transfer covers. These and the 291's are known for the covers coming loose at the seam where stihl glues, epoxies or whatever they use to attach them to the cylinder.

 

[hacskaroly]

Another thing to check is the transfer covers. These and the 291's are known for the covers coming loose at the seam where stihl glues, epoxies or whatever they use to attach them to the cylinder.

Yes, that is a good point, had a customer that was using a 311 to mill and got it so hot the transfer cover blew off...JB Weld to the rescue!! That is one thing I like about Husky cylinders, they put screws in their removable transfers!

 

[Agent Smith]

Yes, that is a good point, had a customer that was using a 311 to mill and got it so hot the transfer cover blew off...JB Weld to the rescue!! That is one thing I like about Husky cylinders, they put screws in their removable transfers!

I did see an ebay aftermarket 291 top end kit recently where the transfer covers were screwed on so kudos to the aftermarket world for going that route. Unless i missed them, it'd be nice if husqvarna sold the xfer cap gaskets by themselves. I've had make a few out of gasket material before. Its tedious work

 

[lehman live edge slab]

Yes the ms 271/291 and 311/391 both had some experience with loose covers but I’m pretty sure the newer ones don’t have covers i know there was some updates

 

[lehman live edge slab]

The two different styles, one has transfer covers and a clamp on boot, the other no covers and screw down style intake boot like a 362.

 

[hacskaroly]

The two different styles, one has transfer covers and a clamp on boot, the other no covers and screw down style intake boot like a 362.

I have only seen the newer style, both of mine have that. Was the other one for earlier 271s or 270s?

 

[lehman live edge slab]

Also i personally don’t think jb weld will do a sufficient job on the covers. Maybe some form of devcon will but jb i personally don’t think will do it. If I found a set of loose covers on a 271 or the like I’d be tempted to clean the epoxy off and weld them on. Even if you used Hobart aluminum stick to weld them in a few spots then sealed with jb weld so it’s just being used for sealer not strength.

 

[lehman live edge slab]

I have only seen the newer style, both of mine have that. Was the other one for earlier 271s or 270s?

Not 100% sure I’ve worked on both some in 311/391 and 271/291 forms. And these are the 271-291 styles no 270 in this that’s different looking all together just like a 280

 

[lehman live edge slab]

Ms 270/280 style cylinder, the ms 280 was the first crack at solenoid control carb. Had an adjustable low speed if i remember and a solenoid tuned high jet. Pre mtronic

 

[lehman live edge slab]

I have only seen the newer style, both of mine have that. Was the other one for earlier 271s or 270s?

I do believe the clamp on intake/glued transfer covers was the old style and they updated to the 362 style screw on boot with no covers to end the issue of them leaking air

 

[Sparky 46]

Welcome to the forums! Possibly an air leak between the carb and cylinder or either of the oil seals. You can get the saw running and then spray non-flammable brake cleaner around those areas, and if there is a leak then the saw will shut down (with no damage), though you could also use (but I don't recommend) carb cleaner which is flammable and if there is a leak, the saw will race - not the greatest thing. Either way you will know if you have an air leak.

Also, the on/off/choke lever is easy to bend if you (or the previous owner) wrench on it, possible that when blipping the trigger it actually connects the contacts to shut it off. I had to replace one of mine because of that.

Thank you I'll go through it.

 

[Sparky 46]

Thank you everyone ! I figured it was an air leak thinning the mixture but didn't know where the trouble points were. Lots of talk about JB weld and found something much better. POR 15 makes a body putty in a tube that air drys hard as a rock and even sticks to plastic fuel tanks. So hard you can't sand it. Find its the best repair putty around but you've got it get it correct the first time, no sanding or smoothing it out after it drys.

 

[lehman live edge slab]

Don’t honestly know how it can be so hard you can’t form it. Honestly depending how old it is you won’t need to worry about the transfer covers because not all have them

 

[Sparky 46]

Well I tore it down and the only possible leak I found was the glue joint between the cylinder and the block. There was oil/fine sawdust across the block where sealer was thin. Having a hard time finding procedure to clean old glue/RTV and redo it. Was going to just make a gasket like it should of been done in the first place but realized clearance on the bearings and seals would be incorrect. Where do I source the sealer and find the repair procedure. Thank you

 

[hacskaroly]

Having a hard time finding procedure to clean old glue/RTV and redo it.

For those saws, you need to use high-temp gasket maker, I use this:



I was looking for a video I have watched, but can't find it, basically, you need to clean off as much of the old stuff as possible and then you put a bead of new. You don't want too much that it squeezes inside the cylinder, but you don't want too little that you end up with leaks. Follow the instructions, I think for this one, you put the gasket maker down and then put the cylinder on and slightly tighten so the gasket maker makes contact with the cylinder all around. Let it sit for an hour (the instructions say how much exactly) then fully tighten it down. You want to make sure the gasket maker goes all the way to the bearings (where the bearing, cylinder and base meet). I recently worked on a MS 291 and 391 and they were the same clamshell setup as your 271.

 

[Merkava_4]

The one thing to remember about 2-cycle engines is that the entire crankcase is the combustion chamber. If you have leaks at the crank seals, that upsets the fuel metering operation tremendously. A good small engine mechanic will check the condition of the cylinder walls and do a compression test if the cylinder walls are scared up. The next thing to do is a pressure/vac test. No point in proceeding if the engine fails the pressure/vac test. If the carburetor doesn't respond to mixture adjustments, that's a clear sign that you have an air leak bigger than what the carburetor can compensate for.

 

[Sparky 46]

For those saws, you need to use high-temp gasket maker, I use this:

View attachment 444627

I was looking for a video I have watched, but can't find it, basically, you need to clean off as much of the old stuff as possible and then you put a bead of new. You don't want too much that it squeezes inside the cylinder, but you don't want too little that you end up with leaks. Follow the instructions, I think for this one, you put the gasket maker down and then put the cylinder on and slightly tighten so the gasket maker makes contact with the cylinder all around. Let it sit for an hour (the instructions say how much exactly) then fully tighten it down. You want to make sure the gasket maker goes all the way to the bearings (where the bearing, cylinder and base meet). I recently worked on a MS 291 and 391 and they were the same clamshell setup as your 271.

Thank you very much. Will Amazon it.