would running 87 octane in a trimmer that require 89 cause hard starting?

[JohnnyG]

I've run them full tilt for an hour straight, which makes me wonder, maybe they got too hot and seized or something.

Being hot, as I mentioned above, would be conducive to pre-ignition. Particularly if there was "some" carbon buildup increasing compression.

 

[ARB1977]

93 in my Sthil and in my Briggs 163.

 

[repairman54]

If in a northern area winter blend fuel in the summer will cause hard restarts due to vapor locking. Makes my 17 hp BS with a fuel pump surge at idle and sputter.
I now try to get stocked up on summer fuel for the winter so if my winter fuel usage is low I'm not having issues next spring or summer.
No E0 locally, have to drive 45 min. for it so 15 gal. of stabilized fuel is always on hand for generator use also. E0 I get is 90 octane.

 

[Chevyc10]

You can buy new recoil assembly $15 on eBa. When pull ropes fray or break I replace assembly. Easy job,4 screws.

 

[jeepman3071]

It is more likely the recoil starter than anything fuel related. Also I highly doubt they are seizing up, you wouldn't be able to pull them over at all, and after a few times of that happening you wouldn't have enough compression to start anymore. Running at wide open throttle for hours under load is how they are designed to run, and will keep your exhaust ports clean.