Stihl Farm Boss

   / Stihl Farm Boss #21  
My Farm Boss MS 290 was hard to start brand new. The service guy gave me these tips for a cold start:
1. Use Full Choke until it "Pops" once.......then
2. Go to 1/2 choke until it starts.

It has worked well ever since. ... that was in 2011....I just service it myself since then and be sure to clean the Spark Arrestor.

Cheers,
Mike
 
   / Stihl Farm Boss #22  
Don't forget about the impulse line...especially if doing a full service with a new fuel lines etc...
 
   / Stihl Farm Boss #23  
oldballs said:
1. Use Full Choke until it "Pops" once.......then
2. Go to 1/2 choke until it starts.
Click to expand...

I've used that on two stroke motorcycles since the 1980s. Recently I have modified it on my saws to three pulls on choke then turn it off even if it did not pop. Seems to result in fewer cold start pulls to get a start, at least on saws that have been run fairly recently and did not have the carb run dry.
 
   / Stihl Farm Boss
  • Thread Starter
#24  
I modified the muffler last night and started the saw. It started fine after about 5 pulls. I still need to tune the carb. It sounds like it's running too fast to me. I purchased a digital tachometer online for 12.99 and will tune it to max out at about 12,000 rpm.

Kevin
 
   / Stihl Farm Boss #25  
The shop manual should specify the speed to tune it to. 12k may be too fast. My saws' specs run from 10.5 to 12.5 and it's not always the larger ones that are slower.
You can also check how it runs in the cut- it should four stroke when cutting when you lift on the saw a little. The cheap tachs don't always work that well.
 
   / Stihl Farm Boss #26  
You may find an inexpensive tach does not have a quick enough response time to tune a chainsaw. Madsen's has a great guide on tuning a chainsaw by ear. Go to this page and click on the Saw Tuning link. You'll need good speakers or headphones to listen to the audio link. The speakers in most laptops are too cheap to hear what is going on clearly.
 
   / Stihl Farm Boss
  • Thread Starter
#28  
The tach matches my CNC mill digital spindle readout within 4 rpm @ 7,000. This is a one time use only as far as I'm concerned. I'll probably lose it in my shed shortly after I'm done tuning the saw. :)

Kevin
 
   / Stihl Farm Boss #29  
NoTrespassing said:
The tach matches my CNC mill digital spindle readout within 4 rpm @ 7,000. This is a one time use only as far as I'm concerned. I'll probably lose it in my shed shortly after I'm done tuning the saw. :)

Kevin
Click to expand...

Some inexpensive tachs will not register high enough RPMs to tune a chainsaw (If I recall, max RPM on my saws is 13,500, almost double your CNC mill). In addition, chainsaws should not be run at wide open throttle under no load for more than a couple seconds, max. A slow response tach will not register the RPMs in that time.

My suggestion is tune by ear, per the link I sent earlier, then if you want, back it up with a double check on your tach. If your tach gives you a wonky reading, I'd be inclined to trust the tuning by ear a whole lot more than an inexpensive tach - as mentioned, it may not accurately read your chainsaw RPM. The problem is, if an inexpensive tach is not reading accurately, it will most likely be reading low. If you try to adjust for this supposedly low RPM by leaning out the engine further, you risk lean-seizing your engine.
 
   / Stihl Farm Boss #30  
The sound it makes four stroking when you lift in the cut is really obvious- waaaaahhh (lift) uunnnnnnhhh. To someone who has tuned race motorcycles it sounds rich. But it's a safe tune for a chainsaw.
 
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