Modded Stihl MS180C / WT215 swap not running right?

[traut811]

Hey guys. Long time lurker, first time poster. You all are awesome so hoping someone may be able to help me out here.

I acquired an MS180C from my dad. It was hurting but had a good bar and chain on it so figured why not. I cleaned it up well and did the following:
-Engine is fresh - piston, rings, cylinder walls are perfect with no grooving, bottom end was sealed with MotoSeal (permatex, its what I always use on powersports bottom end cases). Ring gap and everything looked fine
-Gapped coil to .003"
-Did an eBay WT215 swap - JB welded the impulse hole and removed the plug/ball in the center to get it to line up correctly. The transfers line up perfectly
-Muffler mod - removed arrestor screen, enlarged baffle holes, bent open fins slightly
-Advanced timing - Per a couple posts on this site, I saw to mark the outside of the flywheel with a reference point, file the key, and rotate anywhere from 5 to 6mm from this OD mark. I went 5mm.
-I plugged the old airbox hole with JB weld since I saw this was no longer needed. Is this recommended, or should I just install the compensation plate "thing" on the WT215 and use this again?
-The rest was just access holes to the H/L/idle screws for the carb
The saw starts up on choke easily (initial start up, it smoked because I used stihl HP premix oil on the cylinder/piston/rings during assembly). As soon as the choke is removed, the saw falls on its face. It will rev up but you cannot let it get below 1/4 throttle without choking it again or it flat will not idle.

I am pretty happy with the high and low speed settings on the carb. They're ~1.5 turns out/ea but can get an exact if needed.

I do not have access to a vacuum tester but can buy one if that is needed. The saw has tons of compression so am not leaning towards that being an issue. It smokes like it's rich and the plug is wet when I pull it.

I'm down to either wondering if timing was advanced too far (it does not seem like this is the case, and have not experienced any kickback when pulling the rope)
or
has anyone had to drill a small hole in the butterfly valve to allow it to idle? This seems excessive on something like this but did not remember seeing that being a "thing" when modding these little saws. I am using the Stihl HD filter. I do not think there are any air leaks. I also do not really think I'm getting any difference with adjusting the idle screw, perhaps the arm is bent where it contacts the tapered end of the idle screw not allowing it to open up enough on idle?



This was a long post (sorry guys). Thanks in advance for any help or advice.

 

[HarleyT]

Put up some pics.

Is the white plastic expander on/in the intake boot?

 

[traut811]

Put up some pics.

Is the white plastic expander on/in the intake boot?

I'll grab a couple pictures in the morning of it together. This is all I had on my phone. They don't show much..
Yes it is installed.

 

[stihltech]

Back to basics. Vac and pressure test a must after that much work. Confused on the carb swap. I take it you plug the pulse line off the bottom of the carburetor and use a hole in the body. Is the hole in the body open for pulse?

 

[ZeroJunk]

Take a picture of the intake manifold that you have modded and the engine side of the carb .

Just curious.

 

[traut811]

Here are a few more

 

[ZeroJunk]

JB welded the impulse hole had me confused. Sorry.

 

[traut811]

Here are a few moreView attachment 1143078

 

[SteveSr]

Here are a few more

That is NOT the impulse hole. It is the carb compensation port hole.

 

[trains]

Is this a genuine Walbro WT215 carb , or just a chinga copy ?

ive had 3 chinga copies that would not work well with this exact mod that you have described, put a gen one on, and worked fine.

edited to add, just put the old compensating cover on the new swapped in carb to keep the air filter assy original.
one one carb, the top cover would not line up and fit the screw holes of the chinga carb.

 

[traut811]

That is NOT the impulse hole. It is the carb compensation port hole.

Yes, correct.

 

[traut811]

Is this a genuine Walbro WT215 carb , or just a chinga copy ?

ive had 3 chinga copies that would not work well with this exact mod that you have described, put a gen one on, and worked fine.

edited to add, just put the old compensating cover on the new swapped in carb to keep the air filter assy original.
one one carb, the top cover would not line up and fit the screw holes of the chinga carb.

It's a China copy I'm sure.

I'll look for an oem walbro if that should be my next step.

I assume no one is needing to drill a hole in the butterfly valve blade for air at idle? Surely jet sizes would be the same I'd think.

I'll remove my compensation plug and see if that will line up first then go from there.

 

[trains]

dont drill the butterfly, if the carb worked correctly, you wouldnt need to, you will only introduce more problems and chase your tail in an endless loop if you drill the butterfly.

get a proper carb that will work, and enjoy the saw.

 

[EchovsStihl63]

I did all of this to mine about a year ago minus the keyway advance and it runs like a dream. Is this what you did as far as plugging the impulse port?

My money is that you have a vac leak somewhere or the idle circuit in your chinesium carb is funked. Back the L screw out like 2.5-3 turns and see if that changes it, if that makes a difference you can move to the next step of determining air leak or carb circuit. If it does not make a difference then pretty good bet something is going on in the carb.

IMHO I would toss the china carb and get a genuine Walbro, that is what I used on mine

 

[stihltech]

The pictures are looking at the wrong side of the carb. We need to see the back side and the intake boot. That is where the impulse hole is.
Want to go nuts? Just keep using those chinesium carbs. Had to remove two off customers saws last week to make the unit run correctly.
Get some good parts.

 

[EchovsStihl63]

The pictures are looking at the wrong side of the carb. We need to see the back side and the intake boot. That is where the impulse hole is.
Want to go nuts? Just keep using those chinesium carbs. Had to remove two off customers saws last week to make the unit run correctly.
Get some good parts.

My wood splitter had a Chinese knock off on it when I bought it. Thing never would run right unless the choke was half on and it would always try to run away as in the governor would not cut it back. Turns out the bore in the carb was egg shaped and I could see light all the way around the butterfly when it was fully closed.

So the governor was working, but there was so much gap around the butterfly it would run past its governed speed even at idle position. The gap was also preventing the venturi from working properly causing it to not draw fuel on the idle/no load circuit hence keeping the choke half closed. I've never thrown a new part in the trash so fast.

 

[ZeroJunk]

Chinese carbs are like a box of chocolates . But, they work fine more often than not.
And, you can buy five or six for what an OEM carb costs.

The problem with them on four cycle motors is they may have the same carb listed for several different CC engines.
Can't be the right jet size for all of them. So, they may "hunt" on you.

 

[NJ1911]

Have a Holzfforma G372 I bought just to play around with and use for cutting garbage wood around the yard. Was good for about 6 months then the china carb lost all adjustment. I noticed it would not reach full rpm so I started adjusting to baseline settings. Turning the idle and high/low screws had no affect, period. Figured I had little money in the saw so I splurged and bought a genuine Walbro. What a difference. Runs like a top now. Real carbs make a difference.