Need Some Quick Advice on High Altitude Issues

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.
DMZX

DMZX

Member
Aug 30, 2010
211
NE. Oregon
My son is with a Forest Service handcrew on the Waldo Canyon fire in Colorado. He sent me an e-mail last night saying they are having issues with their saws due to the altitude (>7,500'). I believe that they run Stihl 460 Magnums. He did not specify what the issues were, but I suspect they are down on power, idling roughly and fouling plugs.

My question is: Can the idle screws be adjusted for high altitude or do those models have "smart carb" technology that compensates automatically.

Any ideas would be most helpful.
 
No reason why you can't lean out the high speed mixture screws a tad. The intellicarb only compensates for a clogged air filter, not atmospheric density. And the MS460 has yet to get the Mtronic system, which I'm sure they're (Stihl) saving for the MS461.
 
  • Like
Reactions: ScotO
Page 43 of my MS250 manual has instructions for high altitude adjustment. (Sorry, it won't let me copy from a PDF document). Perhaps you can download the 460 manual.
 
DanCorcoran said:
Page 43 of my MS250 manual has instructions for high altitude adjustment. (Sorry, it won't let me copy from a PDF document). Perhaps you can download the 460 manual.
Click to expand...
Good idea. I will look at my 290 manual and see if it says anything and then see if I can download the 460 manual.
 
DMZX said:
My son is with a Forest Service handcrew on the Waldo Canyon fire in Colorado. He sent me an e-mail last night saying they are having issues with their saws due to the altitude (>7,500'). I believe that they run Stihl 460 Magnums. He did not specify what the issues were, but I suspect they are down on power, idling roughly and fouling plugs.

My question is: Can the idle screws be adjusted for high altitude or do those models have "smart carb" technology that compensates automatically.

Any ideas would be most helpful.
Click to expand...

@ over a mile high, the air is way thinner. Tuning a saw @ altitude is no different than at sea level. L screw in till the idle is smooth, rev it up tune the H screw out or in till the saw is 4 stroking slightly. Lay it in the wood & listen, it should smooth out under load. Burp the throttle from Idle to wot, id the saw revs up quickly w/o hesitation set the LA or idle screw in or out till the chain just stops moving. If it bogs going up, give it a little more on the L side & adjust idle as described. Imo a saw needs tuning to match changing weather & temp conditions to run optimally anyway. Pretty easy with a little practice. If they've been running those saws rich for long, the spark arrestors should be cleaned out too. Thank them for the job they do from me please. A C
 
My son contacted me tonight and said they leaned them out a bit, but the problem seems to be the engines loading up due to very high temps and gas boiling up in the tanks.


He says direct suppression efforts are futile as long and the wind blows and temps remain at +90 degrees. They are moving along the flanks, protecting structures and keeping one foot in the black.

My kid is a Squad Boss on the crew. 5 season under his belt. Got his head screwed on tight. Iraq war vet. He will keep his people safe.

Fossil, I will e-mail him that link so he can store it on his phone for future reference. Thanks.

AC, I copied your post and will send it as well, with your thanks.
 
Gotta be one of the most dangerous, difficult and frustrating jobs there are anywhere. Anybody who would go in there and do that is a hero in my eyes. I wish them well. Rick
 
  • Like
Reactions: ScotO
fossil said:
Gotta be one of the most dangerous, difficult and frustrating jobs there are anywhere. Anybody who would go in there and do that is a hero in my eyes. I wish them well. Rick
Click to expand...

Yea, + about 100
 
All them folks that looks at large fire and thinks to themselves "yea, I can take that!" is a hero. The men and women that are fighting these wildfires gotz some true grit and my full respect.
 
Status
Not open for further replies.
Top Bottom
Back