Stihl fs110r help needed

[taandctran]

I know guys it isnt a chainsaw but I figured yall could help more then anyone else. I have a stihl fs110r (4-mix engine) trimmer that I have been messing with for a week or 2. When I got it it would run really rough and smoke alot (I think the timing was off) I've taken it apart and cleaned it and made sure the timing was right. It wont start at all with the choke on. It will start with the choke off and run at wide open throttle (but it will pulse or race and not run smooth). and will run at idol when the idol is turned way up. Some times it will start right up and sometimes it wont start at all. I'm wondering what everyone think it is the coil, carb (with I've cleaned but not rebuilt) or some other problem. I'm wanting to get some ideas before I start dumping alot of money (which I dont have) into this thing.

 

[lwn9186]

Sounds like a bad module throwing the timing off. Check the warranty on them as Stihl has had problems with earlier ones.

 

[taandctran]

i already talked to stihl about that. no luck on that. guess i`ll have to spend the $55 on one

 

[taandctran]

any other ideas before I spend the $55 on it for no reason???

 

[THALL10326]

I know guys it isnt a chainsaw but I figured yall could help more then anyone else. I have a stihl fs110r (4-mix engine) trimmer that I have been messing with for a week or 2. When I got it it would run really rough and smoke alot (I think the timing was off) I've taken it apart and cleaned it and made sure the timing was right. It wont start at all with the choke on. It will start with the choke off and run at wide open throttle (but it will pulse or race and not run smooth). and will run at idol when the idol is turned way up. Some times it will start right up and sometimes it wont start at all. I'm wondering what everyone think it is the coil, carb (with I've cleaned but not rebuilt) or some other problem. I'm wanting to get some ideas before I start dumping alot of money (which I dont have) into this thing.

It should not start from cold without the choke. Sounds like you got a leaky carb issue. Remember too at full throttle that unit will sound like its missing because it is. The coil has a built in governour. When that unit reaches around 10,000 rpms the governour cuts the coil on and off so the unit will not over rev, makes the unit sputter at wide open throttle. Need to make sure you got the valves adjusted just right too. One good way to tell is by how hard it cranks. If it cranks hard something is wrong, that unit cranks effortlessly. Valves too loose will make it crank like a bear...

 

[taandctran]

So you thank maybe it is a carb issue??? I dont think it ever gets to 10,000 rpms. it just sputters. Could that all be carb related???

 

[THALL10326]

So you thank maybe it is a carb issue??? I dont think it ever gets to 10,000 rpms. it just sputters. Could that all be carb related???

Well if its right it should top 10,000 rpms. It sounds more carb related than ignition. The modules on them do one of three things, they work great, not at all or get stuck in the advance mode in which the unit will spit but will not start for nothing.

Note too those 4-mixers never sound as though they are turning the R's that they are. Have you got a tach, if so check the R's, you will be surprized at how fast it may be running...

 

[taandctran]

Come to thank of it. The Primer bulb has never really filled up with fuel. I thought maybe it was just a 4-mix motor, but after you said something about a leaking carb it kind of makes me think it is the carb now. It would probaly be simpler to just rebuild th carb instead of trying to find the leak?? Thanks for the help Thall, I wish I had your knowledge!!!

 

[THALL10326]

Come to thank of it. The Primer bulb has never really filled up with fuel. I thought maybe it was just a 4-mix motor, but after you said something about a leaking carb it kind of makes me think it is the carb now. It would probaly be simpler to just rebuild th carb instead of trying to find the leak?? Thanks for the help Thall, I wish I had your knowledge!!!

Welp if its not priming right you have a restriction in the carb somewhere or a stuck check valve in the primer itself, both would need striaghtened out in order for that machine to run correctly....

 

[taandctran]

A rebuild kit would help with all that??? or not?? thanks again thall you are the man with stihls

 

[THALL10326]

A rebuild kit would help with all that??? or not?? thanks again thall you are the man with stihls

A kit and a real good cleaning may do the trick, sure can't hurt....

 

[taandctran]

what is the best stuff to clean a carb with? should I let it soak in something or just spray it with regular carb cleaner?

 

[taandctran]

ok guys I rebuilt the carb and it is getting gas. but it still wont run. I think I have a bad coil. Any way you can test it? It is getting "fire" but I still think it is bad. I just dont want to buy a coil if that isnt the problem

 

[newworld]

stihl 4 mix problems......

if you have :
--no start, or may start w starter and then stall or stall w throttle open
--will start and run and then stall or run on idle and never throttle up

after you have replaced or cleaned carb, checked fuel lines, opened up exhaust and checked valve clearance....

THEN

its a cam problem. if the unit has a lot of wear...ie usage....the cams will wear out making it hard to set valve clearances and create all sorts o problems...i got this tip from another poster....but it applies to these 4 mix engines:

DO THIS-

usually the answer is a replacement of the short block.
if you dont have funds etc and are mechanically capable...take the starter off and then take off cover for cam....first check for bearing wear....if the crankshaft moves even a little, on either side flywheel or starter side any play at all...your bearings are shot and need to replace them and the crankseals.

then take a look at your cam lobe...the cam gear is plastic. the lobes wear and also check your cam metal cover holes....are they oval? usually after many years of usage the pins create an oval shape in cam holes on cover and on the cam lobe....if you dont replace the cover ie funds low...then take coke can and make a interference fit for the pin in cover.

next...
any wear on cam lobe...replace this part....it is plastic so it will wear out. there is no repair for this.

my experience is that on 4 mix engines after lots of usage the cam is the main suspect if all other things are eliminated as the reason for the problems.....

 

[SteveSr]

Have you checked the spark screen in the muffler? I have seen these carbon up and get so restricted the machine won't hardly run. Take a propane torch and burn it clean. If it don't glow red you haven't got it hot enough!