BR600- 4mix carb. help needed

[jk14]

I just picked up a very clean low hour br600 with the 4 mix engine. Guy said it didn't run I got it home and put fresh fuel in and it popped off but wouldn't really idle. I need a little help on where to set the mixture with the limiters removed (spec?) I imagine that it's quite different than a 2t.

The carb. had limiters on it so I adjusted them to spec. 3/4 out and the threads felt very loose and the low screw fell out. It looks like someone was in fooling around so I removed the limiters. I found the hi screw 9 turns out and I'm guessing the lo was about the same since it took a little over 8 turns to seat it.

And yes I'm adjusting the valves as we speak.



Edit: I adjusted the valves which were definitely tight and set both screws at 2 turns out. It seems to run pretty good there smells a little rich at idle but burns clean wot. I only ran it for 30 seconds though because I don't want to kill it. Any advice would be appreciated.

 

[jk14]

Ok in case anyone else may need the info. I found a technical manual online and the spec without limiters is:

2 turns out on the low
3-1/2 turns out on the high

That's what I set mine to after adjusting the valves and it runs like a top now. I also have a link to the manual if anyone wants it.

 

[Whiskers]

Glad you got it going. The valves can also get crud built up over time not allowing them to open and close. Stihls decarbonizer works wonders on cleaning them out.

 

[Carhartt]

You will love that 600. I used to say you can blow small children down the street with a BR 600. Try and put the shoulder straps on at about half throttle. I watched a friend of mine spin himself around a cpl times when he borrowed mine.

 

[Simondo]

I just picked up a very clean low hour br600 with the 4 mix engine. Guy said it didn't run I got it home and put fresh fuel in and it popped off but wouldn't really idle. I need a little help on where to set the mixture with the limiters removed (spec?) I imagine that it's quite different than a 2t.

The carb. had limiters on it so I adjusted them to spec. 3/4 out and the threads felt very loose and the low screw fell out. It looks like someone was in fooling around so I removed the limiters. I found the hi screw 9 turns out and I'm guessing the lo was about the same since it took a little over 8 turns to seat it.

And yes I'm adjusting the valves as we speak.



Edit: I adjusted the valves which were definitely tight and set both screws at 2 turns out. It seems to run pretty good there smells a little rich at idle but burns clean wot. I only ran it for 30 seconds though because I don't want to kill it. Any advice would be appreciated.

All i can put forward is......I Dont know what Stihl USA say, but the one thing i can pass on to you is the 4 mix engines are supposed to be run on Stihs HP ultra and not the lower grade oils. Thats what Stihl UK tells us anyhow. The 4 mix line trimmer engines are a bit erratic runners if the valves are not right to ....a general 4 mix thing it looks like.

 

[jk14]

Glad you got it going. The valves can also get crud built up over time not allowing them to open and close. Stihls decarbonizer works wonders on cleaning them out.

I'm going to pull the muffler and take a look at the exhaust valve this weekend. How is the stihl decarbonizer applied? (Mixed with fuel, fogged in intake, applied directly to valves?)

You will love that 600. I used to say you can blow small children down the street with a BR 600. Try and put the shoulder straps on at about half throttle. I watched a friend of mine spin himself around a cpl times when he borrowed mine.

Yeah I'm already digging it. It seems like a giant upgrade from my antique echo pb400 that it will replace.

All i can put forward is......I Dont know what Stihl USA say, but the one thing i can pass on to you is the 4 mix engines are supposed to be run on Stihs HP ultra and not the lower grade oils. Thats what Stihl UK tells us anyhow. The 4 mix line trimmer engines are a bit erratic runners if the valves are not right to ....a general 4 mix thing it looks like.

Yeah I believe the stihl ultra was supposedly developed for the 4 mix engines. However the ultra that we have here in the USA is FB rated so I'm not huge fan of it. I generally stick with FD rated oils.

 

[Onan18]

I'm going to pull the muffler and take a look at the exhaust valve this weekend. How is the stihl decarbonizer applied? (Mixed with fuel, fogged in intake, applied directly to valves?)


Yeah I'm already digging it. It seems like a giant upgrade from my antique echo pb400 that it will replace.



Yeah I believe the stihl ultra was supposedly developed for the 4 mix engines. However the ultra that we have here in the USA is FB rated so I'm not huge fan of it. I generally stick with FD rated oils.

Pull the spark plug out, get the piston to TDC. fill the combustion chamber with it, let sit for 15 minutes, WITH EYE PROTECTION ON AND OUTSIDE pull the engine over several times, re-install plug, fire up blower and stink up the whole neighborhood.