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I have a STIHL KM110R Power head with a 4mix engine that works great. However, I do not put many hours on it because I only use it to trim a large hedge. I am interested in finding out how the 4mix engines are holding up in the BR600 back pack blowers, or other units with 4mix engines, that would probably get heavy use by professionals. How expensive is it to do the required extra maintenance of valve adjustments and cleaning out carbon deposits? It is my understanding these additional maintenance procedures have to be done every 139 to 150 hours. I put a lot of hours on my BR420C back pack with the 2-stroke engine with out this additional expense. Would you buy another machine with the 4mix engine, or would you go back to a 2 stroke engine? Thanks for your commments.
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I was told by a dealer here in Austin to stay away from the 4mix engines. Said they had a shop full of them in for repairs. -
I have two BR-600s and a HT-100 with 4Mix engines. No probelms at all.Incitatus for the US Senate !Comment
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I've been using my BR600 blower for 3+ hours/day for the past few weeks now. Not one problem (though it is still relitively new). One downside to the 4Mix engines is they are not designed to run at the higher rpms you'd be used to for a 2 cycle engine....though they do have increased torque.
Eventually ALL 2-cycle equipment will have to comply w/ new EPA standards....meaning you WON'T see traditional 2 stroke engines AT ALL! For Stihl to have some issues regarding the 4Mix engines is to be expected, but at least they began the venture of designing a new engine long before the EPA deadline....that's more than can be said for some other brands out there.
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I have a BR600 with approximately 300 hrs on engine. No problems runs as good as the day I bought it. Checked the valves at 150 hours and they were within spec. I won't check them again til it gets hard to start.
Jason
P.S. 4-mix definitely runs better with 89 octane or higher!
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All my small equipment is the sthil 4 mix engines (trimmers, edgers, hedgers. and blowers). I have had them since not long after they came out and I love them. I had had very few problems with any of them. I have yet to have one wear out on us. From my understandings the 4mix has just as much torque as the old 2strokes but just does not get get there as fast. It takes the 4 mix longer to get up to speed then a 2 stroke. I was also told that the 4 mix can run at half throttle and have more torque than a 2 stroke while burning less fuel.
But with all that a side, I love my sthils and I would have nothing else.Comment
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What are you commercial guys doing about removing carbon from your 4 mix engines? I believe the maintenance schedule calls for removing carbon deposits (de-cokeing) every 150 hours. Does this have to be done by a dealer, or can it be done by the owner? If it must be done by the dealer, how much does it cost?Comment
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Had some of my 4mixs going on three years now it seems like and never done any such thing to it. Only maintence I do to them is change the plugs, fuel filter and air filter at the end of each growing season and clean them every once ina while. Now I do run 89 octane gas in all of them. Can't really tell a differance between 89 and 87 in how they run but I just do for some reason.Comment
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Use Opti-2 oil at a 100:1 ratio and forget about carbon problems. Use the "Search" feature, this has been gone over before.Originally posted by cranheim
Personally, I run my 4-Mix units on Opti-2 (as with all 2 cycle equipment) at 100:1 and haven't had a single problem. Even the spark arrestor screens in the exhaust stay clean.
Oh, and Mastermower: RedMax has long had the StratoCharged 2 stroke. It is a unique design, and is a real beast in the power department.Woody
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Thanks to those who replied. It appears the maintenance recommendations to remove the carbon in the 4 mix engines every 150 hours is not being done by those who responded. I have heard the new STIHL Ultra 2-stroke 100% synthetic oil is supposed to reduce these carbon deposits according to STIHL. However, I have not seen and change in the recommended maintenance procedure by them. If you professional users can get away without doing any special maintenance, it may not be as critical as I thought it was. I have always tried to follow the manufacturer recommendation for long product life.Comment
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I have a fs85 trimmer and a fs90 4mix trimmer which is the replacement model for the 85 i wont even begin to tell you how unimpressed I am with the fs90 uses more fuel, harder to start and if you let off the throttle too soon it acts like it wants to die. Talked to the dealer he says its normal. Talked to another dealer said the same. I think it is a load of crap if you ask me. I wish I had bought a fs80 and bought a solid shaft to go with it; it would have been a fs85 then!Comment
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This is an old thread but I am now having problems starting my BR-600.
It starts then shuts off after about 15 seconds. It has new spark plug, air filter and plenty of compression.
What would be the diagnostic steps to follow? Of couse I don't have the manual any more...
It is acting almost like a awitch has gone bad.
Thanks!Incitatus for the US Senate !Comment
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spark arrestor screen maybe clogged
try taking it out completely and see if it changes anything.Originally posted by buster57 View Post
steveComment
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Fuel tank not venting, coil going bad maybe? Fuel filter clogged?Originally posted by buster57 View PostComment
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