Stihl tech help on a 110 r 4 mix

I have a stihl 110 r 4 mix that will not run.

I have adjusted and decarboned the valves

New carb, new coil, new plug

Piston looks good

screen is clean

It will fire on SF with upper cyl lube. (dont give me the story)

Fires good with my ZAT 4 ing tester

Thank you,
Rob

Have you removed and inspected the valves/seats? Have you checked the compression? There is nothing I hate more than a troublesome 4 stroke trimmer.

They helped me retire early......

I have removed the valves and cleaned up the valves and seats. I also leak down tested it and it has a very slight ex leak. It acts like the new carb is not letting fuel thru. I have pressure and vac tested the carb and all is good.

I hear ya fish! I have worked on 2 of them now and they might be my last ones!

Rob

Ok I got it.....Late last night I remembered it will not build vacuum if the valve cover is not sealed!. I had the cover off and forgot it used very little pulse to pull fuel in.


Symptoms that caused this repair.

No start
Carb diaphragms were pretty stiff so I went with obvious and replaced the carb

still no start(has spark) will not pop off of starting fluid.

I then lean to the valves hanging open. I decarbon them and adjust them.

still no start.(has spark) I pull the cylinder and clean piston,valves,muffler screen.

Still no start (has spark) I change the coil ( they had problems with them sticking in advance)

Now will fire on starting fluid but not stay running.

I bump my head and remember I need to seal valve cover to make vacuum in order for the impulse line to work the carb so it will pump fuel thru the carb.

NOW RUNS!!!

Rob

Great! You are now the Stihl 4 mix guru!!!!!!