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When squirting a few drops of fuel into the carb it will start but dies as soon as the squirted fuel is used up. Primer bulb is filled up with fuel. Fuel filter in tank has been replaced. It ran a few days ago. Stihl dealer says trimmer is not worth fixing, it has no compression which is probably BS. I replaced the carburetor and messed with the H and L needles. Exhaust is unrestricted. If compression was the problem I guess it wouldn't start when squirting fuel into carb. Any ideas??? Btw, does this engine have compression release to make starting easier?

My concern at the beginning is what is the compression reading. Above 90 then I would consider replacing the carb and see what happens.

4180 4 mix engine.

Yes it has a decompression setup so the valves needs adjusting every so often. Now does a special feeler gauge as most are too wide to use.

I personally use a different minimum compression number of at least 100 psi.

Also the lat time I brought it was around $50 and but now you can get a repair kit for thru Amazon under RB-287. CTS has two kits for under $10 including shipping. It is mostly a stiffen metering diaphragm not allowing the metering needle to open up.

I just added those to my next purchase from Amazon myself.

I just picked up my trimmer from the dealer and I had a long talk with the service tech who worked on it. He said he did a compression test and a leak down test and the leak down test failed miserably. He said that the compression loss is caused by a faulty exhaust valve. Now I feel newly encouraged and my nest move will be to remove the head and take a good look at the valves, valve seats, cam, push rods etc. Updates will follow.

Thanks StarTech for the decompression info. How does it work on that engine?

It opens one slight right before TDC compression stroke. As for which one I haven't paid attention but I think it would be the intake valve.

Thanks StarTech. I couldn't have asked for a better explanation. Before I tear into that engine I will check and make sure that the decompression nipple moves freely and is not stuck

I got the engine apart and it looks like the Stihl tech was right. looks like a valve job will make things well again. The cylinder walls don't have a scratch on it and the piston and rings definitely look good. Also the decompress nipple on the cam is good but I may replace the cam anyway even though the old one looks pretty good. Both valves look good but the valve seats are in bad shape. Question, can I replace the valve seats? That would be great. Pop new seats in and put in new valves and that should fix my problem

Stihl only sells the cylinder with the valve seats installed.

PN 4180 020 1209 Cylinder
PN 4180 007 1036 Gasket Set
PN 4180 030 1800 Cam Wheel

But first see if you can clean them up with fine valve grinding compound via a valve job procedure. They may just be carbon up. But sometimes they are too damage to clean up.

Stihl only sells the cylinder with the valve seats installed.

PN 4180 020 1209 Cylinder
PN 4180 007 1036 Gasket Set
PN 4180 030 1800 Cam Wheel

But first see if you can clean them up with fine valve grinding compound via a valve job procedure. They may just be carbon up. But sometimes they are too damage to clean up.

Stihl only sells the cylinder with the valve seats installed.

PN 4180 020 1209 Cylinder
PN 4180 007 1036 Gasket Set
PN 4180 030 1800 Cam Wheel

But first see if you can clean them up with fine valve grinding compound via a valve job procedure. They may just be carbon up. But sometimes they are too damage to clean up.

Stihl only sells the cylinder with the valve seats installed.

PN 4180 020 1209 Cylinder
PN 4180 007 1036 Gasket Set
PN 4180 030 1800 Cam Wheel

But first see if you can clean them up with fine valve grinding compound via a valve job procedure. They may just be carbon up. But sometimes they are too damage to clean up.

I was afraid of that. I don't see the seats in the parts list. Just for the hell of it I will call Wilson-Dismukes (Stihl headquarters who happen to be in town) and talk to one of the techs. I know they probably can easily replace the seats if they wanted to. Otherwise I will give it a shot rebuffing the seats. It doesn't make it any easier that they are so far up in the cylinder and not easy to get to. I am surprised that no enterpreneur has picked up on that and makes them and provides that service to replace them.

ueww40 said:

I got the engine apart and it looks like the Stihl tech was right. looks like a valve job will make things well again. The cylinder walls don't have a scratch on it and the piston and rings definitely look good. Also the decompress nipple on the cam is good but I may replace the cam anyway even though the old one looks pretty good. Both valves look good but the valve seats are in bad shape. Question, can I replace the valve seats? That would be great. Pop new seats in and put in new valves and that should fix my problem

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Anyone that suggests lapping the old valves to the old seats should be ignored. All you'll do is have shiny valve faces and seats. Seats are interference fit....there is no "popping in" or out to be had. If you had a welder and were proficient you could run a bead around the inside of the seat to shrink it and they mostly fall out with a bit of persuasion. They can be cut out but that's a guide and cutter either on a vertical mill or can be done on a lathe in a pinch. Cut out, as in, remove all but a couple of thousandths to allow collapsing the thin shell of metal left. Then you have to make sure there is sufficient interference on the new seat/head interface and use nitrogen to cool the seat, heat the head and drop it in. Which ultimately brings up the question.....are there any seats that can be bought for this engine?

Yes, many small engines, Briggs I am familiar with, have a compression release for easy starting. I had one that wouldn't turn over with the starter motor but started fine after adjusting the valves. The cam has an extra lobe before TDC that opens the exhaust valve to releave the compression a little for easier starting. If the exhaust valve adjustment is too loose the valve doesn't open and the compression is strong enough to make pulling it through hard. You should look it up, but I think the adjustment is .002 on the feeler gauge for the exhaust valve and like .005 for the intake valve. I adjust several with good results.

RevB you are right. Theoretically none of this is easily done, but there is always the genius who comes up with a way to make this an easy job. As a matter of fact, while I was messing around with the cylinder, one of the valve seats actually fell out of the block. That's how I know what the thing looks like, how small it is and with the proper tool and procedure should be easily replaced. If I was younger I would actually dig into this and see if I could develop a way to provide this service to replace valve seats and guides on 4 Mix engines for a flat fee of $75 plus shipping. If Stihl doesn't want to make the parts available they are always available aftermarket as good or better quality. But for right now the only way to fix my trimmer is to get the Stihl part number 4180-020-1209, which is on order. But I have contacted Stihl USA in Virginia Beach and told them how I feel about this (see next post)

This is the complaint that I filed with Stihl USA and a case number was assigned to it:

I am the owner of a FS111R trimmer, which failed even though I only use Stihl oil since the trimmer was new. According to my local Stihl dealer who did a leak down test, the problem was with the valve train and not worth fixing. After I disassembled the unit it was clear that the valve seats were in bad shape and needed replacing. The valves are good, the piston and rings are good, the cylinder walls are good and yet the only way to fix this minor problem is to replace the entire block and piston which is about $170 just for parts, because I was told that the valve seats are NOT available. Therefore the entire engine is junk over a couple of $2 parts. What a shame and disservice to your customers who have 4 Mix engines. May I suggest that you include valve seats in your parts lists to allow us to fix our engines instead of having to junk otherwise perfectly good engines. Please do. It's the right thing to do. Thank you. P.S. If you find it in your heart, maybe you can mail me a couple of valve seats for the 4180 020 1209 engine. I will be grateful forever. Thanks!"

Update! I haven't heard from Stihl and I don't expect to. That's fine. In the meantime part number 4180 020 1209 arrived last Friday and yesterday I started putting everything back together. By the way I got a great deal on this part from a Stihl dealer in Texas ($95 + shipping) for a brand new block, piston with rings and new valves and springs. Can't beat that. Now I practically have a more or less new FS111R for about $120 and a new one is almost $500. Anyway as I was putting everything back together yesterday (piston, crank and crankcase I had just finished) I couldn't believe my eyes when I discovered that none of the holes had any threads in them. How is that possible? Did the official threader come to work one morning hung over like hell and forgot to put the threads in the holes. I was devastated to say the least and had it not been a Saturday I would have been on the phone calling the seller and most likely making a fool of myself. So I started digging online and soon found out that Stihl uses all self threading bolts on their engines. That's how they come, just holes - no threads. I had no idea, probably like a lot of other people. Once I knew that, I finished up my engine today. Except for one bolt, which I broke. Got to go into town tomorrow and get one from our Stihl dealer. You can't just go to Home Depot and get a metric bolt. No sir, these are all special Stihl bolts. And installing the piston pin retaining clips is something to right a song about. Not that easy, they like to get away and if they do you will never find them again (Murphy's Law). In the next couple of days after the trimmer is completely back together and hopefully it runs like a dream. I will let y'all know, how this worked out.

Sounds like someone just violated his Stihl dealer contract....

StarTech said:

Sounds like someone just violated his Stihl dealer contract....

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....like how? And if you are talking about me I don't have a contract with anybody

My FS111R is all back together and runs like it was brand new. I couldn't be more pleased. Since this is practically a new engine is there a break in procedure that I need to follow or can I start trimming away like nothing ever happened? Btw StarTech, you never explained what you meant by this dealer contract violation. I am really curious to know.

Either everybody has gone on vacation or nobody knows anything about Stihl engines and I thought this was the Stihl forum - very disappointing to say the least. But maybe somebody can answer this. Does a 4 mix engine fire at every revolution? I am also just curious about that too.