Stihl BG85C Blower Carb ?'s

[billyjoejr]

Just got a new Stihl BG85C blower.
The dealer set it up and it runs ok, but being anal, I am trying to get the perfect tune.
I am using an EDT8 and understand tuning a chainsaw.
But with blowers being under a constant load, I am unsure of the settings.

Owners manual says low idle is set with 'L' screw at one turn out and 'LA' screw is turned in until engine runs smooth then a quarter turn back. 'H' screw turned out 3/4 of a turn or turned out to stops.

With these settings the blower is blowing smoke when accelerated (running rich on low idle?). If I turn the 'L' screw in 1/4 to 1/2 a turn (leaning it out) the rpm's pick up, the engine smooths out and the smoke goes away. I then adjust the 'LA' screw to get the idle at 2800 rpms. If this was a chainsaw, I'd say that the settings are now perfect, but the blower manual seem pretty adamant on the 'L' screw being 1 turn out.

1: Am I ok with the 'L' screw being 1/2 to 3/4 of a turn out from gently seated?

2: On the 'LA' screw, I just can't tell when the engine 'smooths out'. So I turn it in until the idle is at 2800 rpm's.(idle speed according to manual). Is this setting correct?

On 'H' screw settings, I read a post by Lakeside that you should lean the 'H' screw out until the rpm's max out, then richen the screw till the rpm's drop 75-100 rpms. My 'H' screw is turned all the way counterclockwise against the stop. When I turn it in the rpm's drop. This tells me that it is running lean. The rpm's are around 7200.

3: Should I cut the tab off the limiter so I can follow Lakeside's directions to make sure I am running safely rich? Or should I just trust Stihl in setting up the carb correctly and leave things alone?

4: Are the limiter tabs on this blower like those I've read about on chainsaws? In that they need a special tool to remove them. And can they be removed permanently or do the mixture screws need them to keep their settings?

And Yes I am aware of the saying "If it ain't broke, don't fix it", but I just can't help myself. :monkey:


And with my previous experiences with the local Stihl dealer, I live by the other saying of "If you want it done right, do it yourself." :greenchainsaw:

 

[Lakeside53]

If this is new you need 5-10 tanks though it to break it in.

If you're worried about the H, follow your 3.

I'd have just left the L and LA alone. There's a big range in acceptable operting envelope on the L... but that increased rpm when you lean out the L is too lean. it''s supposed to be slightly rich. Put LA where you want - for a stable stable idle.


I don't know what carb you have (there are many) but it's likely that the H cap just pops up - a screw driver beneath will lift it to clear the stop.

 

[billyjoejr]

Thanks Andy,
Thats what I wanted to hear.
Just worried about running it to lean and it looks like I was on the 'L' screw.
Only one tank of fuel through it, so it looks like I got some work to do to break it in. The weather is perfect for that today.

Happy Thanksgiving
Billy

 

[billyjoejr]

One more question.

I am using Shell Premium and Stihl Ultra at 50 to 1.

With the 'L' at one turn out and the 'H' turned counterclockwise against the stop, the blower blows some smoke.
In my understanding of tuning a chainsaw it is running rich.
If I turn the 'H' screw clockwise the smoke goes away but the rpm's drop. Telling me it is now starting to run too lean.

This is my first brand new two cycle anything.
Is this normal and I just need to patiently wait for the first 5-10 tanks of mix to be used before before I try adjusting beyond the standard settings?

Sorry if this is redundant. Day off + new toy + several cokes and whiskey = This is driving my nuts and don't want to be too rich or too lean........ :crazy1:

Edit: Looking back on this I realize I'm that customer that I hate dealing with. The one that knows just enough get in trouble and needs to be bailed out.
Note to self: Just leave the d@m things alone and trust the pro's. :deadhorse: