Stihl Kombi Motor KM 56 RC-E -Low Power, Won't Idle - Muffler?

[DuckRyder]

As in the title - last time it acted like this the dealer removed the spark arrestor stating they sometimes clogged...

Now I've replaced the plug, cleaned the air filter and checked the bore best I can (cant get bore scope in item plug hole) and all looks well. If i remove the muffler it will idle though loudly.

Can't see anything in the muffler but do they go bad/clog?

It is over 10 years old if it matters...

 

[UncleDave]

Carb gunked up?

 

[fantastic]

If they removed a "screen" aka spark arrester they can absolutely get gunked up. Wife was out weed eating & sounded like it was running out of fuel. So I went digging & found it plugged. The muffler itself is possible but you'd have to remove it & see. If it will rev up all the way with little "Bogging" then it's not clogged muffler & more of a carb/fuel issue. I've had good luck with foreign carbs off the jungle store but they will need to be properly adjusted but you'd want to do that with any carb. While you're into it if it's not too much of a hastle I'd go ahead & replace the ignition coil too. 10 years of heat can take their toll. Just tear into it & see what you can find.. then order parts.

 

[wpod]

There is a need to diagnose the problem

 

[Brian123]

As in the title - last time it acted like this the dealer removed the spark arrestor stating they sometimes clogged...

Now I've replaced the plug, cleaned the air filter and checked the bore best I can (cant get bore scope in item plug hole) and all looks well. If i remove the muffler it will idle though loudly.

Can't see anything in the muffler but do they go bad/clog?

It is over 10 years old if it matters...

What 2 stroke oil are you using?

 

[DuckRyder]

Stihl Ultra or the Mot0Mix

 

[jake wells]

Stihl Ultra or the Mot0Mix

Stihl ultra is garbage.

 

[DuckRyder]

Cleaned the muffler following you tube videos.

Twisted the idle speed in half a turn, attachment still does not run, appears all is well... no excuse to buy a 94R

 

[Brian123]

Stihl ultra is garbage.

You might have a point jake, Stihl never doubled the warranty when you bought the Orange Bottle 2 stroke oil. Buy our equipment and we will double the Warranty if you buy Stihl Ultra.
It kind of makes you think why are they doing this, maybe Stihl knows something, meaning they realize that using this 2 stroke oil will eventually lead to problems after a certain amount of time. When you have a problem you either get it fixed or like most people you just go buy another piece of equipment.

You can save yourself problems by using a better 2 Stroke Oil:

1) Amsoil Saber Pro
2) Echo Red Armour
3) Maxima K2
4) Bel Ray HR-1

 

[Old fart]

Sorry but it ain’t your oil. You guys really think Stihl oil is subpar? I got news for you, the non synthetic (orange bottle) was just fine. The silver bottle (synthetic) is better. Been running Stihls since the late 80’s with no issues.And that old FS75 weed eater is a late 80’s model that still has the original spark plug, and has only had the primer bulb replaced by me. None of these has ran on anything but Stihl oil there entire lives. I have heard this same garbage on the arborist sight till I am sick of it.

 

[Old fart]

Duck, did this problem start after it set for an extended period? Or did It just start?
If it was after setting for a while, pull the carb and inspect and clean it. Probably a jet varnished up. If it just started all at once, probably got a piece of trash in a jet. Pull carb and inspect and clean. If you are carful you can take the carb apart without using any replacement parts. These carbs are a lot easier to work on than what most people let on. A magnifier works good to inspect any small passage.

 

[ARB1977]

I run Amsoil saber at 80:90-1 in my Sthil combi. Ran moto mix fuel for 4 years because of the warranty. Amsoil the last 4-5 years with 93E10. Took the screen out after a week of owning it. No issues.

 

[jake wells]

You might have a point jake, Stihl never doubled the warranty when you bought the Orange Bottle 2 stroke oil. Buy our equipment and we will double the Warranty if you buy Stihl Ultra.
It kind of makes you think why are they doing this, maybe Stihl knows something, meaning they realize that using this 2 stroke oil will eventually lead to problems after a certain amount of time. When you have a problem you either get it fixed or like most people you just go buy another piece of equipment.

You can save yourself problems by using a better 2 Stroke Oil:

1) Amsoil Saber Pro
2) Echo Red Armour
3) Maxima K2
4) Bel Ray HR-1

The all mighty stihl ultra in a 2021 stihl ms261

 

[Old fart]

So what’s your problem with it? No scoring shown on the piston, there is carbon built up on top of the piston and in the exhaust port which can be easily removed with a little decarbing additive in the fuel. I have never seen a 2 stroke that didn’t have carbon built up in those areas.

 

[Jethro_Bob]

In my experience, Stihl Ultra doesn't really burn in a two-stroke. It turns to a black tar that finds a place to build up over the years. Usually the muffler under the one baffle.

 

[jake wells]

So what’s your problem with it? No scoring shown on the piston, there is carbon built up on top of the piston and in the exhaust port which can be easily removed with a little decarbing additive in the fuel. I have never seen a 2 stroke that didn’t have carbon built up in those areas.

Ultra is blended for the 4 mix engine go ask stihl they don't recommend the orange bottle in the 4 mix engines. A JASO FD oil performs far better in a conventional or strato charged two cycle.

 

[Old fart]

Ok, just so we are clear here are some cold hard facts. The oil is supposed to be used a lubricant for 2 cycle motors. Flashpoint on 2 cycle oil is where the oil stops being a lubricant. Flashpoint of Stihl ultra is 428*
Flashpoint of Amsoil saber is 248*
The old Stihl universal is 160*
It’s pretty clear which one Will protect your motor the best, and it’s pretty clear to see why Stihl will double your warranty if you use Ultra. Carbon buildup on a 2 cycle is normal, and it happens on 4 cycle motors as well due to certain additives in gas. Pick up a owner’s manual for a Yamaha or Mercury outboard, 2 or 4 stroke made in the last 30 years and read what they recommend. Yamaha suggestion is to run ring free and Mercury has their own version to clean carbon. They both recommend adding to every tank of fuel. On Yamaha HPDI fuel injection if you didn’t and you ran Yamalube, it would build up carbon and jack the rings out and catch on a port and rip the ring lands off of a piston at pretty low hours. Yamalube is great oil, but built up carbon very quickly because of a high flashpoint.

 

[DuckRyder]

Duck, did this problem start after it set for an extended period? Or did It just start?

I think it just started, I have been traveling a lot and my bride uses the battery blower/trimmer more when im gone but im sure she used it some. When i was home for a few days after 6 or so weeks is when i noticed it wouldn't idle.

Only think I'm confused about now is why it was necessary all of a sudden to crank up the idle screw. guess it being like 12 years old i couldn't complain much if it blew completely up tomorrow....

 

[thastinger]

You might have a point jake, Stihl never doubled the warranty when you bought the Orange Bottle 2 stroke oil. Buy our equipment and we will double the Warranty if you buy Stihl Ultra.
It kind of makes you think why are they doing this, maybe Stihl knows something, meaning they realize that using this 2 stroke oil will eventually lead to problems after a certain amount of time. When you have a problem you either get it fixed or like most people you just go buy another piece of equipment.

You can save yourself problems by using a better 2 Stroke Oil:

1) Amsoil Saber Pro
2) Echo Red Armour
3) Maxima K2
4) Bel Ray HR-1

I buy it when I buy a new Stihl just because they double my warranty, it sits on the shelf and I use the VP 2 stroke oil instead.

 

[UncleDave]

I think it just started, I have been traveling a lot and my bride uses the battery blower/trimmer more when im gone but im sure she used it some. When i was home for a few days after 6 or so weeks is when i noticed it wouldn't idle.

Only think I'm confused about now is why it was necessary all of a sudden to crank up the idle screw. guess it being like 12 years old i couldn't complain much if it blew completely up tomorrow....

Stihl OEM Carbs are cheap. I'd just pop another on and move on.

It's probably not your oil, but gas that went bad. Happens all the time in small engines that sit with pump gas.

Grab yourself a 5 er of sunoco ultra 95 and get some into each of your small gas devices before the winter, switch back to pump during hard use season.