stihl no start

[BZB_Helpers]

I got a 3yr old stihl FS110RX (4mix). It will not start no matter what until after 20mins of pulling the string. It'll run fine and start fine again as long as you do it within half hour. Gas dribbles out the carb also when cranking.
-I've changed the carb and that didnt help at all.
-I have a spark outside the cylinder but dont know about inside the cylinder, if the cylinder pressure is putting out the spark.
-I've adjusted the valves and it ran fine for about a week then this started.
-I adjusted the valves at TDC, is that correct or is there some other spot to adjust at?
-How do i check the coil resistance? there are three wires:blue(case ground), black(on/off)?, plug wire.

This is the numbers on the coil:
4180 1301 a
mc 4180
411


Anyother ideas?

[Andyshine77]

If ti has spark, it has spark.:)

The 4mix motors do have problems with carbon build up. Check the compression. The carb may also need a rebuild.

[BZB_Helpers]

carb is completely NEW not just with a rebuild kit.
i took the muffler off before i got the new carb and it didnt help.

[Jay74]

It could be the coil... stihl has a lifetime warranty on coils. Sounds like you should find a competent mechanic. It should take no longer than 20 minutes to find the problem.

Here's what I've found with stihl 4-mix:

Zama carbs - check valves always going bad.
Valves never far enough out of adjustment to cause no start.
And don't touch the valves unless you're a Stihl tech.
If over 150 hours decarbon the cylinder.
Stihl coils are unreliable.

The only stihl machines I recommend are the 4-mix and chainsaws. If going two stroke I only recommend Shidaiwa.