Stihl Kombi Edger Versions FCS-KM

[KerfWatcher]

Looking for some experience / background on the different versions of the stihl FCS-KM, which is the straight shaft stihl kombi edger attachment. From what I can tell, 3 different versions have been made from oldest to newest.

1.) Orange body, one wheel, flex drive shaft
2.) White body, 2 wheels, solid drive shaft
3.) Orange body, one wheel, solid drive shaft.

I own 1 and 2 listed above, the local stihl rep was able to confirm that 3 above did have an old version with a flex drive shaft (1), and recommended that I update 1 above to 3 above via installing a solid drive shaft ~$20.

Does anyone have experience positive or negative with the flex shaft in the Kombi edger attachment or other attachments? These are used on KM90R and KM131R power heads.

 

[KerfWatcher]

Well, I did some digging.....actually read the manual (shocker I know). Found out that the KM94R, when running the edger, should swap the solid drive shaft out with a flex one. My understanding is that the KM94R is a 2 stroke, non 4 mix, light weight version of the kombi system...So why does the KM94 require a flex drive shaft for the edger attachment? I looked through a few other kombi attachments (ex bed redefiner) and the manual seems to rate them for use on the 94R with a solid shaft?

 

[Justin Taylor]

Well, I did some digging.....actually read the manual (shocker I know). Found out that the KM94R, when running the edger, should swap the solid drive shaft out with a flex one. My understanding is that the KM94R is a 2 stroke, non 4 mix, light weight version of the kombi system...So why does the KM94 require a flex drive shaft for the edger attachment? I looked through a few other kombi attachments (ex bed redefiner) and the manual seems to rate them for use on the 94R with a solid shaft?

Maybe more rpm? But that doesn’t make too much sense since the 4mix motors have more power and I think they rev to 12k

 

[tfp]

The flex shafts break fairly frequently for us but if you use them on good paths that don’t have any concrete slag or otherwise under the surface to hit you should get decent mileage out of them. Also beware of hitting any concrete if the pathways or whatever you are edging aren’t aligned perfectly. If conditions are really bad (long grass with a thick root mat, dirt or silt buildup on the edge), consider ‘barking’ off the edges with a line trimmer first and then run the edger over it. We started doing this and it reduced the number of shaft breakages, but a lot of our paths are uneven so we still break some. We can’t get the straight shaft version here which is unfortunate as I’m sure a solid shaft would last much longer.

 

[KerfWatcher]

Thanks guys, still doesn't answer the question as to why one should not use a solid shaft in the edger when running the KM94R power head.