# Stihl FS76 Trimmer Smoking



## JimB6267 (May 1, 2009)

I know this is an older trimmer/brushcutter but it has had little use. I am going to use it with a four blade brushcutter head and adjusted the RPM as guided by the owners manual to about 10,000 rpm using a tach. It smokes heavily, more so than with the autocut string head adjusted as guided by the owners manual. The rpm following the autocut head procedure is about 15,000 to 16,000. Is the heavy smoke a problem or to be expected with the high speed screw turned in to control the speed? Idle speed, by the way, is about 5,000 rpm.


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## geogrubb (Jul 28, 2006)

I don't know what you are using to check the rpm but they sound too fast, if you have adjusted the high needle in so the engine runs the fastest and do not set it back until it starts to sound a little like a 4-cycle you will burn it up, 5000 rpm is not an idle, it is more like the max for a lot of engines, the only reason I know for a 2-cycle to smoke is the richness of the fuel mixture and old/slow burning fuel. Have a good one. Geo


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## rotti1968 (Apr 26, 2009)

the low end should be around 2800 to 3000 rpms, the high end max should be 9,700 to 11,300 max blade or trimmer head.What is your fuel mixture? It should be 50:1 for all stihl products, using a part or full synthetic mix oil, with the premium fuel as recommended by stihl.your screw setting should be 1 to 1.25 turns for both the high and low speed adjustments to start with then tune from there . I just looked and I can not find any stihl trimmer that they recommend to be set at 15,000 to 16,000 rpms. The highest I find is 13,000 and that is for the fs 550 56 cc brushcutter the biggest unit they make .


I just double checked the fs 76 service manual and its 2700 low end rpms,9700 to 11,00 high end rpms and 1 turn each on the high and low and tune from there .


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## JimB6267 (May 1, 2009)

I know the fuel mix is old so I will start with making a fresh batch. I am using a Fluke 88 meter with an inductive pickup set to the 2 cycle rpm setting.


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## JimB6267 (May 1, 2009)

Thanks for the rpm specs. As you probably guesed I used the 4 cycle setting on my meter. I double checked my meter book. A fresh fuel mix makes a world of difference. Thanks for the support.


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## ald hg (Mar 2, 2012)

*???? FS 76 service manual????*



rotti1968 said:


> I just double checked the fs 76 service manual and its 2700 low end rpms,9700 to 11,00 high end rpms and 1 turn each on the high and low and tune from there .



I noticed in ur post , which I included above, that u checked ur manual for the Stihl fs 76. so i was wondering if u could tell me where I could download a copy of it. I would really appreciate it a lot. I've Been looking, but haven't had any luck finding one anywhere. please, I would appreciate any help from anyone. thanks!!!!


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