MS361 high idle problem

[captndavie]

So my 361 has a high idle problem. I have pulled covers off and see no obvious leaks. Spraying starting fluid around crankcase stalls it out BUT I can't tell if it is being pulled into air cleaner. Could totally be the case. I also tried to pressurize the crankcase with a low air pressure by blocking off carb and exhaust. I can't tell see or hear any leaks but that doesn't mean there aren't any as I am not an expert at this project. I also pulled the sprocket and brake drum off. I did find that the bearing inside had wood pieces in it. Could this cause a high idle due to increased load? I don't see any other problems. My only other thing to think of could be fuel lines. Oh and the carb to block boot looks ok. Didn't take it off but it does look fine. Any advice or thoughts here? I don't want to take it to stihl shop and someone just adjust the throttle down and not really fix it. Help!!

Thanks
David

 

[captndavie]

I did notice a bit of exhaust leak around muffler when I pulled it. Just thought about that. Could that be my culprit?

 

[redoakman]

I THINK your over thinking this your self have you ever had the carb tuned at all.. yes there maybe a air leak but sometime carbs have a mind of ther own

 

[pantelis]

So my 361 has a high idle problem. I have pulled covers off and see no obvious leaks. Spraying starting fluid around crankcase stalls it out BUT I can't tell if it is being pulled into air cleaner. Could totally be the case. I also tried to pressurize the crankcase with a low air pressure by blocking off carb and exhaust. I can't tell see or hear any leaks but that doesn't mean there aren't any as I am not an expert at this project. I also pulled the sprocket and brake drum off. I did find that the bearing inside had wood pieces in it. Could this cause a high idle due to increased load? I don't see any other problems. My only other thing to think of could be fuel lines. Oh and the carb to block boot looks ok. Didn't take it off but it does look fine. Any advice or thoughts here? I don't want to take it to stihl shop and someone just adjust the throttle down and not really fix it. Help!!

Thanks
David

What about vacuum test, the carb is ok ??

 

[old-cat]

Spraying starting fluid around crankcase stalls it out

I think you have an air leak. I'd check the intake boot and impulse hose.

 

[captndavie]

I need to get a real vacuum test kit. I pressurized the case but didn't have a gauge or the ability to leave it pressurized for more than a several seconds. I used a valve stem and held it over the spark plug hole.

 

[captndavie]

Where is the impulse hose?

 

[old-cat]

I NEVER use pressure/vac testing. The best way to learn saw maintenance is take that thing apart. You WILL find the bad part. You might want to ask in the beg for manuals thread for the STIHL Service Manual.

 

[RiverRat2]

???

 

[AKDoug]

I NEVER use pressure/vac testing. The best way to learn saw maintenance is take that thing apart. You WILL find the bad part. You might want to ask in the beg for manuals thread for the STIHL Service Manual.

Really? I've found dozens of bad crankcase seals that looked perfectly fine. On Saturday I found an air leak from the crank case gasket into the oil tank AND just out the top behind the muffler. When the crankcases were split there were no signs of leaking through them. I'm sorry, but not using pressure and vacuum to test a saw results in way too much wasted time disassembling stuff that may not be needed to be taken apart.

 

[tree monkey]

no more then 10 psi, pressure or vac, or you will start blowing things apart

 

[old-cat]

Really? I've found dozens of bad crankcase seals that looked perfectly fine. On Saturday I found an air leak from the crank case gasket into the oil tank AND just out the top behind the muffler. When the crankcases were split there were no signs of leaking through them. I'm sorry, but not using pressure and vacuum to test a saw results in way too much wasted time disassembling stuff that may not be needed to be taken apart.

I don't disagree with you even the slightest Doug. I have my way of doing things that works for me. I'm not dead yet, I'm always learning!

 

[AKDoug]

no more then 10 psi, pressure or vac, or you will start blowing things apart

Amen to that ... I did take a MS250 that was toast up to 20 PSI before the seals let go, just to see how much it could take.

 

[tree monkey]

Where is the impulse hose?

next to the intake boot

 

[nyctreeman]

Starting fluid ... 2-stroke engines love starting fluid

 

[captndavie]

Thanks Tree Monkey.

 

[captndavie]

I ended up needing a fuel line and pickup assembly. Runs great now.

 

[sunfish]

I ended up needing a fuel line and pickup assembly. Runs great now.

That's always the first thing I check and usually just replace it.

 

[captndavie]

It does have this odd sounding chirp at idle. I don't know if I just never noticed it before and I am paying more attention to it because of the past idle problem or not. But it's kind of a whistle chirp sound and only at idle. Is that normal and I'm just listening too close to it or does that indicate something else amiss? Otherwise it runs great. Been noodling some big maple with it today and it eats that stuff like its nothing.