I've been using one of these from new for six years everyday. It is still running fine. I checked the valve clearances after 5 years, they were fine, a small adjustment to one. All I've done is put stihl hp super oil mix through it and used it. An ingenious design, and believe me it works.
The crankcase must be air tight just like a 2 stroke in order to lubricate properly. If maintained in that condition, the valves kept in adjustment, with good mix tuned to run the proper rpm, they will last as long as any other. And cc for cc, they produce more torque than 2 stroke. You will bog an FS 250 down before you'd bog down an FS 131.
I'll have to disagree.the fs 250 is a better option when it comes to trimming, maintenance.the 4 mixes are known for failed cam gear,bad crank seals, seized piston.you would have to mix it more than 50;1 if the oil do dissipate and turn into heat,it builds up inside the block, you're got a busted block,melted cam gear,while the fs 250 is still going strong.
I got 2, FC95 and FS130. Both work fine, however, they are twitchy - not as smooth as a 2 stroke. I've not put much mileage on them (2012), but will probably replace cams soon. (Cams very inexpensive). I also only run them on non-ethanol fuel.
True.. the crankcase pulses cause the turbulence. It is a pulse though and not suction. Suction only moves one way and pulses move both ways. It also is not enough of a pulse (dictated by the displacement of the engine) to totally exchange all of the air/fuel mix in the bottom end. Having talked with several dealers and independent shops the consensus is they make decent power but are marginal on bottom end longevity due to the method of oiling the bottom end (crank and rod).
your opinion of 4 mix is very poor . The problem is your comparison to a two stroke. You are correct on all points. However, i find you in error by omissions of important factors that make them one of the best most torque powerfull light, quieter, and cheap for the returns it provides. Im a contractor and made the change to 4 mix. I retain one small Stihl multi 2 stroke for hedging. These things are reliable easy to start abd easy to adjust or break down for parts replacement. the parts are cheap. Everything about them saves time and money. The one big must is operate them exactly as instructed and they are the best machine for today .
I've been using one of these from new for six years everyday. It is still running fine. I checked the valve clearances after 5 years, they were fine, a small adjustment to one. All I've done is put stihl hp super oil mix through it and used it. An ingenious design, and believe me it works.
Best run on the special 4 mix fuel made by stihl.
my BR 600 and HT 131
running for 6 years now
with no problems and burns clean.
2 stroke FTW!
The crankcase must be air tight just like a 2 stroke in order to lubricate properly. If maintained in that condition, the valves kept in adjustment, with good mix tuned to run the proper rpm, they will last as long as any other. And cc for cc, they produce more torque than 2 stroke. You will bog an FS 250 down before you'd bog down an FS 131.
I'll have to disagree.the fs 250 is a better option when it comes to trimming, maintenance.the 4 mixes are known for failed cam gear,bad crank seals, seized piston.you would have to mix it more than 50;1 if the oil do dissipate and turn into heat,it builds up inside the block, you're got a busted block,melted cam gear,while the fs 250 is still going strong.
Been running mine for 12 - 13 years. Never adjusted valves. replaced spark plug probably only twice.
Use Amsoil Saber 2-Stroke oil @ 50-1 or 40-1
I got 2, FC95 and FS130. Both work fine, however, they are twitchy - not as smooth as a 2 stroke. I've not put much mileage on them (2012), but will probably replace cams soon. (Cams very inexpensive). I also only run them on non-ethanol fuel.
On the 4 mix there's not a sump pan for oil and uses 2 cycle oil boy aintvthat messed up
I can't figure it out either. Shouldn't real oil be added into the crank case?
stihl actually bought the 4 mix engines from shindaiwa
Probably why they've canned them and gone to the two mix two-stroke version.
Oil doesn't get into the crankcase by hope, it gets forced there by vacuum.
True.. the crankcase pulses cause the turbulence. It is a pulse though and not suction. Suction only moves one way and pulses move both ways. It also is not enough of a pulse (dictated by the displacement of the engine) to totally exchange all of the air/fuel mix in the bottom end.
Having talked with several dealers and independent shops the consensus is they make decent power but are marginal on bottom end longevity due to the method of oiling the bottom end (crank and rod).
your opinion of 4 mix is very poor . The problem is your comparison to a two stroke. You are correct on all points. However, i find you in error by omissions of important factors that make them one of the best most torque powerfull light, quieter, and cheap for the returns it provides. Im a contractor and made the change to 4 mix. I retain one small Stihl multi 2 stroke for hedging. These things are reliable easy to start abd easy to adjust or break down for parts replacement. the parts are cheap. Everything about them saves time and money. The one big must is operate them exactly as instructed and they are the best machine for today .
this guy doesn't have a clue about this motor ! I've got one runs fine !
They do run ... until they don't.
Yip their rubbish , another stupid idea I’ve just done one with a seized small end which shattered the piston , I certainly wouldn’t buy one