Stihl Ms 180 2-Mix Carb issues?

[KostasVolos]

There is a blocked passage.
I love how everyone wants to get rid of the carburetor. Thousands of not millions running just fine. There are passages in the throat that I clean with a tag wire. And the jet. Pretty reliable carb for the abuse they take. (Work on Amish saws sometime)

Yesterday I had the exact same issue as the one the OP has (or hopefully had ).
I followed your advice and cleaned the idle jet passages
( not with a tag wire-BTW what exactly is a tag wire ? )with a carb spray.Problem solved!
Thank you,sir !

 

[ZeroJunk]

One off-topic question. Are there MS180 2-mix saws in the US, or just MS181?

On-topic comment: while I don't like doing this, sometimes I get to the point of buying a 10 dollar Ebay carb...just as a test.

That is a good question. I don't recall seeing one. The MS181 intake is an entirely different animal.

 

[KostasVolos]

One off-topic question. Are there MS180 2-mix saws in the US, or just MS181?

On-topic comment: while I don't like doing this, sometimes I get to the point of buying a 10 dollar Ebay carb...just as a test.

From what I'm aware of the answer is no,the MS170 2-mix and the MS180 2-mix chainsaws are not available in the US market.
Their non-strato alternatives are the only ones available .
One simple way to distinguish which is which is that the 2-mix chainsaws use the NGK CMR6H (or the Bosch USR7AC or equivalent ) spark plug ,while the non-stratified ones use the NGK BPMR7A ( or the Bosch WSR6F or equivalent ).

The 2-mix engine bears also an
electronically controlled ignition coil ,equipped with an processor which limits the rpms once a preset limit is reached and offers also variable timing .

Modding the stock carb of the
2-mix chainsaws seems to work
better than replacing it with a fully adjustable one .
Not quite sure as to why's that.
BTW ,the stock carb has at it's output venturi a plastic "separator" which redirects the idle fuel in a different intake boot channel ,than the one WOT fuel goes into.
Fully adjustable carbs lack that black plastic "separator" .
Maybe that plays a role of some sort.

The MS171 and MS181 are available both in the US and in EU.They have different air filters ,double butterfly carbs ,more complicated throttle and choke linkages ,spring AV and larger bar oil tanks ( which might mean that they have high flow oil pumps also ).

 

[Dellirium]

Back with an update.
Got the Chinesium Carb, and did some mods on it. It had the impulse hole offset, but because it also had a channel that traveled to the center of the carb body i was able to drill another hole that matches the impulse line on the chainsaw.
Had it started and kind of adjusted, but i didn’t block well enough the other impulse hole, so it started leaning on me because of the air leak that came from the other hole.
Now i’ve plugged the hole with some metal epoxy and i’m currently waiting on it to dry.
I’ll be back again with results.
Up until now it looks promising.
If it works after the epoxy cures i’ll quickly cut out the spark arrestor from the muffler, enlarge the holes of the exhaust diffuser and i may get a fully working 2Mix adjustable carb saw.

As for the other carb i took out the welch plugs, found some dirt there, i cleaned it, and i’m currently waiting on a rebuild kit with some new welch plugs

 

[KostasVolos]

You will have to install a small screw at the trigger slot ( where the throttle wire seats ) in order to achieve full throttle lever engagement to WOT.

Also you have to plug the small upper hole of the air filter housing
( facing the carb ),the one that the carb snorkel fits into . Otherwise "dirty" air will be sucked in.

 

[Dellirium]

I saw that i have to either straighten the throttle lever or to add a screw on it.
I cannot place the old cap on the new carb. It has some dimples which won’t match so i let the old one on.
After plugging the hole i was forced to readjust the carb, kind of hard, but managed to get some good results.
I’ll wait on it to cool down now to see how it cold starts, and if it starts fine, then it’s done. If not, i’ll see what i can do.
For now, it starts on half of cord when hot, steady idle, fast response to wot.

 

[KostasVolos]

I had the same issue with @Dellirium ,but with a MS170 2-mix .
Cleaned the idle jet passages with
carb cleaner spray and tested the saw . For the first 10 minutes or so
it seemed that the issue was fixed...But no.
It was idling ,but gradually the rpm
dropped till the saw died.
Once more ,dismantled the carb and cleaned the idle screw cavity and checked if the pump needle is
closing and then I noticed that there was fuel on the outer side of
the metering diaphragm .
Replaced with a new one ,
along with it's gasket and the saw now runs like a dream .

Actually I find those 2-mix carbs
easy to clean and service.

And with a few mods ,the saw really "wakes up" .

 

[lone wolf]

There is a blocked passage.
I love how everyone wants to get rid of the carburetor. Thousands of not millions running just fine. There are passages in the throat that I clean with a tag wire. And the jet. Pretty reliable carb for the abuse they take. (Work on Amish saws sometime)

That tiny port in the throat?

 

[Dellirium]

I did that the first time, even replaced the gaskets with a Stihl OEM kit and no luck, now i’m waiting on the welch plugs to see if it’s fixed, if not, it will be replaced since not even ultrasonic cleaning and 2 carb sprays fixed the issue

 

[Dellirium]

That tiny port in the throat?

I belive he’s reffering to a serrated type, looks like the carb cleaning wire from the brush kit.
However i use another method, i’m using printer nozzle cleaning wires, the kit starts from 0.15mm so they are pretty small

 

[stihltech]

High speed valve jet issue.

 

[lone wolf]

High speed valve jet issue.

Next thing is are those available to be replaced ?

 

[KostasVolos]

The MS171 and MS181 are available both in the US and in EU.They have different air filters ,double butterfly carbs ,more complicated throttle and choke linkages ,spring AV and larger bar oil tanks ( which might mean that they have high flow oil pumps also ).

On second thought ,the MS171/181 may have higher fuel
efficiency ( consumption -wise ) than their 2-mix MS170/180 "cousins" thus the larger capacity bar oil reservoirs of the former.
It a logical assumption that the capacity of the bar oil tank is in
accordance with the running time the fuel tank capacity provides ,
on a 1:1 ratio.

The 2-mix MS170/180 have :
250 ml fuel tank volume
145 ml bar oil volume

The MS171/181 have :
270 ml fuel tank volume
265 ml bar oil tank volume

 

[stihltech]

Next thing is are those available to be replaced ?

Not worth it. I will have to look. I won't do one. Low success rate.

 

[SteveSr]

Next thing is are those available to be replaced ?

Yes, For Zama carbs. some sizes are available, as I recall, mostly from Stihl. I went looking for ways to slow down some 170s and 180s that were still too lean at sea level.

 

[KostasVolos]

Yes, For Zama carbs. some sizes are available, as I recall, mostly from Stihl. I went looking for ways to slow down some 170s and 180s that were still too lean at sea level.

Those are the main jets ( nozzle assembly ) .But check valves are not "screw in" like main jets but they are "punched in" brass fittings.

 

[KostasVolos]

Yes, For Zama carbs. some sizes are available, as I recall, mostly from Stihl. I went looking for ways to slow down some 170s and 180s that were still too lean at sea level.

For both the MS170/MS 180 modding the stock Zama
carb consists of three steps :

1) Adjust the metering level to be flush or almost flush with the carb body (use an old cash/credit card ,no need for a special tool really )
Usually they come from factory with the metering lever quite below the " max rich setting " .

2 ) Replace the main jet with two sizes larger jet .For example , if the stock carb has a 0.43 jet ( it should be marked with "43") replace it with a 0.45 one ( marked "45" ) ,if stock carb has a 0.45 one ,replace it with a 0.47 one .It can be as simple as visiting a chainsaw workshop and asking if you can salvage some jets from thrown away carbs .Two sizes larger jets will cover the operating from sea level up to about 1000 ~1500 meters of altitude .The saw will be running a bit rich out of cut ,but it will be fine during a cut and won't bog down.

3 ) Cancel the auto compensation feature of the intellicarb and introduce an atmospheric pressure reference to the metering diaphragm. This way the carb will stop adjusting for leaner mix as the air filter gets gradually dirty.
Drill one or two 1.5 mm dia. holes somewhere on the metering diaphragm cover and seal the snorkel that goes into the air box .
For the sealing a variety of agents can be used as epoxy glue,cold weld glue,RTV silicone ,etc.All it needs to be done from now on is to periodically clean the air filter with pressurized air or boiled water .

While it lacks the adjustability of a fully adjustable carb ,
on the other hand the saw will be running richer , it won't bog down and saves from the carb adjusting hassle on such small saws.

This mod if combined with mm and a drilled air box insert ,will definately "wake up" those little saws.

@Dellirium
Hey !
Didi the adjustable carb mod worked for you ?

 

[Dellirium]

For both the MS170/MS 180 modding the stock Zama
carb consists of three steps :

1) Adjust the metering level to be flush or almost flush with the carb body (use an old cash/credit card ,no need for a special tool really )
Usually they come from factory with the metering lever quite below the " max rich setting " .

2 ) Replace the main jet with two sizes larger jet .For example , if the stock carb has a 0.43 jet ( it should be marked with "43") replace it with a 0.45 one ( marked "45" ) ,if stock carb has a 0.45 one ,replace it with a 0.47 one .It can be as simple as visiting a chainsaw workshop and asking if you can salvage some jets from thrown away carbs .Two sizes larger jets will cover the operating from sea level up to about 1000 ~1500 meters of altitude .The saw will be running a bit rich out of cut ,but it will be fine during a cut and won't bog down.

3 ) Cancel the auto compensation feature of the intellicarb and introduce an atmospheric pressure reference to the metering diaphragm. This way the carb will stop adjusting for leaner mix as the air filter gets gradually dirty.
Drill one or two 1.5 mm dia. holes somewhere on the metering diaphragm cover and seal the snorkel that goes into the air box .
For the sealing a variety of agents can be used as epoxy glue,cold weld glue,RTV silicone ,etc.All it needs to be done from now on is to periodically clean the air filter with pressurized air or boiled water .

While it lacks the adjustability of a fully adjustable carb ,
on the other hand the saw will be running richer , it won't bog down and saves from the carb adjusting hassle on such small saws.

This mod if combined with mm and a drilled air box insert ,will definately "wake up" those little saws.

@Dellirium
Hey !
Didi the adjustable carb mod worked for you ?

Hi, sorry for the delay, yes it did. But to some degree.
I’ve modified the carb impulse intake position to center on the impulse tube of the chainsaw.
I couldn’t replace the cap with the old one, so i let it be.
Adjustment wise, i had to richen up the mix 1/4 of a turn after adjusting the carburetor the correct way (would run too fast). This may be related to the carb’s chinesium quality.
Other than that, and the 3 holes that i had to drill it works and starts great. Sometimes it would die after one sec. on the first start, but starts up super fast after that. For now i’ll let it be and see how it does. Will check it after 1 month

All being said, i may have one of the very few (if not only, can’t know for sure) stihl ms 180 2 mix converted to an adjustable carb

 

[KostasVolos]

Hi, sorry for the delay, yes it did. But to some degree.
I’ve modified the carb impulse intake position to center on the impulse tube of the chainsaw.
I couldn’t replace the cap with the old one, so i let it be.
Adjustment wise, i had to richen up the mix 1/4 of a turn after adjusting the carburetor the correct way (would run too fast). This may be related to the carb’s chinesium quality.
Other than that, and the 3 holes that i had to drill it works and starts great. Sometimes it would die after one sec. on the first start, but starts up super fast after that. For now i’ll let it be and see how it does. Will check it after 1 month

All being said, i may have one of the very few (if not only, can’t know for sure) stihl ms 180 2 mix converted to an adjustable carb

I also did notice that my MS180 was running leaner with the WT-215 clone carb than the stock one.Had to adjust the L & H screws beyond the 1 or 1 1/4 turns anti clockwise recommended .

Maybe because that those chinese clones lack an acceleration pump or because their gaskets are of low quality.

I'm not so sure that those "ordinary " carbs can cooperate finely with a strato engine
( since the strato engines seem to use special carbs ).
At my case it was a PITA to adjust the chinesium carb .
Either the L adjustment had to be
overly rich in order to get fast throttle response from idle to WOT
and the H screw had to be adjusted somewhat lean ( since the idle circuit was delivering more fuel than normal ) or in order for the H screw to be about one turn out the L screw had to be adjusted leaner than 1 1/4 out ,
which then would make the saw
hesitate to accelerate from idle to WOT.
Maybe there's an issue with the metering diaphragm gasket or
the main jet valve .Did not
investigate it further.
Just modified the stock carb and
the saw now is running fine.

 

[Dellirium]

No issues on the H part, fast response high rpm, i even engaged the limmiter a few times, i believe that drilling the hole for the impulse line did the trick just fine, and the pumping is on point. However for the mixing issues i did not check the jet sizes, maybe they are different size, hence the adjustment problems. All’n all i’m kinda happy with my results. If i get the chance to pick up a wt-215 for a bargain i might test that out too. But here is too expensive to buy a new one (80$) which defeats the purpose (my purpose)