Rev Limiters

[jsd176]

Not really sure where to post this, but here goes. I while back I posted that I bought a new FS130 trimmer. After using it for a few minutes, I opened it up to full throttle at which point it start to vibrate substantially. Well I just picked it up from the dealer and they told me that the reason it vibrates at full throttle is because of a rev limiter. Does this round right? I sent Stihl an email asking the same question. Maybe some dealer/techs on here can shed some light on this for me. I researched the 4mix trimmers before buying and this never came up. I can't imagine they would make a trimmer that you can't run at full throttle. Any input would be greatly appreciated.

Thanks in advance.

 

[Rookie1]

Stihl must know what rpm is the max for that engine. I am guessing it would rev til it breaks and that wouldnt be good.

 

[husky362]

put it in grass

its a 4 mix it just sounds like its not turning the rpms it's probly turning over 9000, under load it shouldnt hit the limiter, stihl use a rev limiter to keep the valves, push rods and springs inside and have a good usable lifespan

 

[Brmorgan]

Are ya sure the head is spooled correctly? I run an FS90 (also 4-mix) for a dozen hours a week or more, and it's butter smooth unless either the line gets spooled a bit funky, or one strand breaks off at the opening where it comes thru the head. I've held it wide-open without a load quite often and have never noticed a vibration I would worry about. However, if one of the strands snaps off and goes back inside the head, it's damn near impossible to hold onto the thing, it vibrates so bad. I'm not gonna say your dealer is full of it because he may very well be right, but so far I haven't experienced the same problems.

 

[Spitzer]

jsd, they do have a rev limiter that kicks in at 10,500rpm, and yes, you will feel it as well as hear it when it kicks in.
I have the KM130 combi, and mine is the same. I don't like the feel or the sound of it when the limiter steps in. Any more than 1/4 throttle when grass cutting in long grass with line or blades, or even the hedge cutter attachment will get it stuttering on the limiter.
The only time it don't hit that limiter is when i use the Blower attachment, which by the way is excellent. That blower holds it back.
I even trimmed the limiter caps on the carb screws and opened the high speed right out to try and get her 4 stroking at WOT, but this made no difference, it still hits that limiter first.
I only run mine at 1/4 throttle or less most of the time, the torque these little engines produce is quite fantastic, even on small throttle openings.
With only needing to run part throttle, i try to safeguard this by useing AMSOIL SABER PRO at 50/1.

Yep, fricken AMSOIL, its the only way to go.

 

[blsnelling]

My KM130 Kombi head has a rev limiter. It does not affect it's use at all.

 

[Spitzer]

My KM130 Kombi head has a rev limiter. It does not affect it's use at all.

Maybe, or maybe not. Tiz there for a good reason though, but it is a pitty the mighty corporation didn't fit them with a better trigger/throttle control. I do find the trigger a bit too sensitive at times and the thing hits the rev limiter when there is absolutely no need to have it revving so high. Perhaps the bike handle versions allow better control in that respect, they certainly are better regarding vibes.

 

[normalspeed]

Many years later : I have same issue, with the unit(fs110) reaching full throttle on 10% trigger, then chocking out & dying. - seems far too sensitive, and after checking everything (and adjusting carb), found the problem.
Next move is to find how the f***k the cable got twisted round the cover screw.