DIR Return Create A Forum - Home
---------------------------------------------------------
Chainsaw Repair
HTML https://chainsawrepair.createaforum.com
---------------------------------------------------------
*****************************************************
DIR Return to: Chainsaws not listed - Gas OPE
*****************************************************
#Post#: 70948--------------------------------------------------
Stihl Yard Boss MM55 Carb
By: qlopp Date: April 7, 2016, 12:40 pm
---------------------------------------------------------
[quote author=660magnum link=topic=2024.msg70942#msg70942
date=1459995593]
I must have missed the specific complete tiller ipl?[/quote]
IPL is Stihl terminology for the parts breakdown booklet,
correct?
[quote]But I could come up with the powerhead ipl as well as the
Kombo tiller head parts?[/quote]
The MM55 (at least the version I bought) is sold as a tiller,
not a Kombi head setup. The attachments that I'm aware of do
not require switching out gearheads, only swapping different
types of blades/wheels onto the tiller shafts. The engine is
much like the Kombi system engine though.
[quote]The powerhead is the same as the 38, 45, 46, & 55 series
weed whackers[/quote]
[quote]Do you have engine troubles or tine/gearbox
troubles?[/quote]
Everything else has been perfect but I have had carburetor
problems from day one. I rarely use this tiller, but every time
I start it in the spring I need to take apart the carb and play
with it. The basic issue is that it is getting unmetered air
from somewhere. Sometimes I have to run it partially choked
just to get a quick job done. Other times it miraculously works
great. I have given up on fixing the original carb and have
ordered one to arrive tomorrow. I don't know this forum's
etiquette on posting links so if you search ebay for this item#
161884709935 (CARBURETOR REPLACES STIHL 4601 120 0600 FOR MM55
MM55C TILLER ZAMA C1Q-S202A) you can see pics of the exact carb
I'm getting. This supposedly aftermarket replacement carb has
squared 90° plastic fuel hose fittings rather than the radiused
brass pipes on the original, but otherwise it looks the same as
my Zama C1Q with casting# 126. It's cheap enough to try. If I
get the tiller running properly I would like to service the
filters, plug, and fuel lines.
The odd thing about this carb, and one reason I'd like to read
more info on this specific unit (still haven't found an exact
source), is the large plastic air nipple cast into the black
plastic housing. Other more popular Zama C1Qs are virtually
identical to mine but they lack this fresh air vent or whatever
it is. Since I have an air leak and the primer bulb isn't
drawing a full charge of gas into itself, I must assume the air
leak that is leaning out the engine has to do with a passage
inside the plastic block or between it and the main casting.
Gaskets and close inspection have revealed no issues but I'm not
a small engine expert.
I will post back when I get the new carb on to update its
running condition, though I feel the real test is to see what
happens next spring since it is always problematic after winter
storage.
#Post#: 70952--------------------------------------------------
Re: Stihl Yard Boss MM55 Carb
By: 660magnum Date: April 7, 2016, 4:00 pm
---------------------------------------------------------
The vent you are talking about just connects to inside the air
filter. Normally there is just a hole in the carburetor cover
for this function.
If the regulator diaphragm vent hole gets plugged, the engine
will stop. A rotor tiller works in such a dusty environment at
times, this was added for reliability. Some Stihl chainsaws have
this.
[img width=800
height=600]
HTML http://i.ebayimg.com/images/g/KTUAAOSwT5tWQ3sH/s-l1600.jpg[/img]
#Post#: 70955--------------------------------------------------
Re: Stihl Yard Boss MM55 Carb
By: qlopp Date: April 7, 2016, 6:30 pm
---------------------------------------------------------
[quote author=660magnum link=topic=2024.msg70952#msg70952
date=1460062810]
The vent you are talking about just connects to inside the air
filter. Normally there is just a hole in the carburetor cover
for this function.
If the regulator diaphragm vent hole gets plugged, the engine
will stop. A rotor tiller works in such a dusty environment at
times, this was added for reliability. Some Stihl chainsaws have
this.[/quote]
Thanks. What would be the downside from strictly a performance
point of view (not durability) if the same shape of C1Q but
without the plastic vent nipple was bolted up to my engine? Or
maybe it wouldn't even fit at all? Just curious in case the
aftermarket knock-off doesn't work.
#Post#: 70958--------------------------------------------------
Re: Stihl Yard Boss MM55 Carb
By: 660magnum Date: April 7, 2016, 7:08 pm
---------------------------------------------------------
I noticed the tiller powerhead has a different airfilter than
the weed whacker.
On my 026 chainsaw, I put a regular carb on the saw and plugged
the hole in the air filter.
I've used the replacement Chinese carbs for the 27.2cc weed
whackers and they've all worked fine.
#Post#: 70966--------------------------------------------------
Re: Stihl Yard Boss MM55 Carb
By: qlopp Date: April 7, 2016, 11:18 pm
---------------------------------------------------------
[quote author=660magnum link=topic=2024.msg70958#msg70958
date=1460074119]
I noticed the tiller powerhead has a different airfilter than
the weed whacker.
On my 026 chainsaw, I put a regular carb on the saw and plugged
the hole in the air filter.
I've used the replacement Chinese carbs for the 27.2cc weed
whackers and they've all worked fine.
[/quote]
Great info, thanks. I'll report back here by Monday on how it
went, unless I am told it should go in another thread or PM
instead. Sorry to hijack this MediaCAT thread if that is what
the consensus is.
#Post#: 71057--------------------------------------------------
Re: Stihl Yard Boss MM55 Carb
By: qlopp Date: April 11, 2016, 2:14 pm
---------------------------------------------------------
The carb arrived ready to bolt on other than needing to swap
over the throttle stop screw. The threads between screw and
casting were not tight enough to ensure the setting would stay
put so for now I used a drop of blue Locktite on the threads.
There is a hollow "hole" cast above the threaded hole that I
presume is used for squirting a liquid sealant (paint drop,
glue, whatever) to lock the screw in place.
It started right up cold but died for a while with the
adjustments I guessed at. I got it to operating temp and set
the screws and all is good now. It even has better top end and
better throttle response than ever before. Like I said, the
original carb was always junk but the last time I checked at the
local Stihl dealer years ago it would have cost >$150 so I kept
putting the project off. If anyone else is hesitant to use a
"Proven Part" carb which looks different than his original Zama
but matches the application, I'd say go for it. Mine had the
area of the lower cover sanded off where "Stihl" had been cast
so I'm guessing this is the same carb that Stihl would sell over
the counter these days, only obsfucated for exclusivity and
warranty reasons.
Final note on the old carb, there was an essentially unfixable
problem in the plastic "vent" housing that caused an air leak in
the primer and feed circuit as well as it would cause gas to
puke out into the air cleaner housing. It was a mess.
Thanks for the great help on this matter!
A couple pics of the new carb, hopefully the ink and casting
numbers are legible.
HTML http://i.imgur.com/LzO6bYj.jpg
HTML http://i.imgur.com/gW2jkfB.jpg
*****************************************************