Crap stihl strimmers

[simonm]

I've got 2 stihl brush cutters that are both a year old, when they get hot they like to run rough as hell and cut out. 

Once they stop they are a pita to start! 

 

Any ideas? 

[Stubby]

1 minute ago, simonm said:

I've got 2 stihl brush cutters that are both a year old, when they get hot they like to run rough as hell and cut out. 

Once they stop they are a pita to start! 

 

Any ideas? 

low compression ?

Edited June 1, 2020 by Stubby

[simonm]

3 minutes ago, Stubby said:

low compression ?

It feels like it when you pull the cord, what's the cause & remedy? 

[Stubby]

Just now, simonm said:

It feels like it when you pull the cord, what's the cause & remedy? 

Cause can be any number of things . Bad mix is one ( old fuel or wrong ratio of oil to petrol )  An air leak is another making it run lean and hot causing damage to the piston .  Wrongly adjusted carb is another . Not saying it is low comp , just a suggestion . take the muffler off and have a look at the piston through the exhaust port . 

[simonm]

How do you adjust the carb? Think they are 1 of them electric things as there's no hi low screws. It's fresh fuel & it's deffo always mixed right. 

[Richard 1234]

9 minutes ago, simonm said:

How do you adjust the carb? Think they are 1 of them electric things as there's no hi low screws. It's fresh fuel & it's deffo always mixed right. 

Change air filter the Auto tune (or whatever it’s called) Stihl strimmers don’t like much crap in air filter. I’ve got a couple of them that do it when air filter is too blocked. When changed start machine and run for 50 seconds on Tickover to reset computer

Edited June 1, 2020 by Richard 1234

[adw]

Most Stihl machines i have seen have compensator carbs, so i cant imagine the air filter would be the issue, unless it is completely blocked.

[spudulike]

3 minutes ago, adw said:

unless it is completely blocked.

And that would never happen would it???

[spudulike]

One year old - I wouldn't rule out the air filter unless you clean them out regularly. Having them block up causes the engine to run rich so the AT leans the mix right down to the point a hot start is a bitch!

Other than that, not sure if it has the small 10mm spark plug but these can become unreliable, more so than the 14mm ones.

Worth checking the compression but with AT....unlikely and you would feel it on the starter. Worth stripping the carb if the air filter and plug don't work, the gauze strainer may be blocked especially if you use the same can for saws and strimmers etc.

[Richard 1234]

1 hour ago, adw said:

Most Stihl machines i have seen have compensator carbs, so i cant imagine the air filter would be the issue, unless it is completely blocked.

Just speaking from my experience with the sodding things! In theory your right but once you put a new filter in it magically works again. I found it surprising how even reasonably clean air filters still didn’t work right. Mine were used all day so needed to work properly so i changed filters probably too often as it’s cheaper than waiting half an hour for it to cool down on hot days.