Welcome to ArboristSite.com! Log in or Sign up to interact with the ArboristSite community.

ArboristSite.com Sponsors
 
 


  1. Please see this post Click Here Please ask questions if you have them!! I hope this is going to be great for us all.
    Dismiss Notice

Should a chainsaw 4 stroke out of the wood?

Discussion in 'Chainsaw' started by pops21, Aug 31, 2010.

  1. pops21

    pops21 Addicted to ArboristSite

    Joined:
    May 8, 2008
    Messages:
    1,197
    Likes Received:
    217
    Location:
    Asheville, NC
    I was doing some thinking today. Is a chainsaw that 4 strokes out of the wood but clears up in the wood in perfect tune? I know some just shoot for a few hundred RPMs below max reccomended RPMs. But which is the right and wrong way. Then there are people that start rich and do timed cuts leaning the saw out till the times peak and start dropping. So is the best answer
    A. Four stroking out of the wood but clean out in the wood
    B. Set to a few hundred RPMs below max recomended RPM
    C. Do timed cuts till you have fastest time

    Sorry if this has already been answered but I feel there is a grey area when it comes to the right tune in the wood. Especially with all the muff mods and porting being talked about. Cause I feel that throws another variable in the mix.
     
  2. maico490

    maico490 ArboristSite Guru

    Joined:
    Jan 19, 2008
    Messages:
    574
    Likes Received:
    150
    Location:
    England
    C is the best way to do it but for most people in the real world A will get the job done. Just relying on setting to an arbitrary RPM can be a short step away from a toasted saw.
     
  3. Tzed250

    Tzed250 Account Hold

    Joined:
    Jul 23, 2002
    Messages:
    7,024
    Likes Received:
    1,102
    Location:
    West Virginia
    .


    mine do....


    .
     
  4. Brian VT

    Brian VT Addicted to ArboristSite

    Joined:
    Nov 9, 2008
    Messages:
    3,174
    Likes Received:
    330
    Location:
    VT
    4-stroking with no load on the engine may mean that it's slightly rich,
    but that's certainly better than it being lean.
    Doing a plug chop will give you a bunch more info. if you want to get closer to perfect. Timed cuts have too many variables.
     
  5. pioneerguy600

    pioneerguy600 Lost in Space Staff Member

    Joined:
    Dec 23, 2007
    Messages:
    36,524
    Likes Received:
    15,727
    Location:
    N.S. Canada
    For general work related saws go with method ," A", if you have enough run time on chainsaws and really know what you are doing method ,"C" would be better. Method,"B", might just toast a saw having carb or fuel problems.
    Pioneerguy600
     
  6. pops21

    pops21 Addicted to ArboristSite

    Joined:
    May 8, 2008
    Messages:
    1,197
    Likes Received:
    217
    Location:
    Asheville, NC
    I tune by ear wanting a light 4 stroke out and as soon as it touches wood it clears up. But some of the newer saws are hard to hear the 4 stroke. What got me thinking about this is alot of videos that are posted on here and on youtube you can't hear the 4 stroke. Especially on modded motors.
     
  7. Taxmantoo

    Taxmantoo Plays with chainsaws

    Joined:
    May 8, 2008
    Messages:
    15,452
    Likes Received:
    13,941
    Location:
    Olivet, MI 49076
    I'd rather bury the bar and tune for peak RPM than do timed cuts. Especially since timed cuts can be helped a bit by tuning for high RPM and building more energy in the flywheel, which is the direction you don't want to go in.
     
  8. SkippyKtm

    SkippyKtm The Lorax, my FIL rip...

    Joined:
    Jan 3, 2009
    Messages:
    2,809
    Likes Received:
    1,278
    Location:
    The quiet corner, CT USA
    Method "A", having it 4 stroke out of the wood, and then 2 stroke when its in the wood is the method I use. So far no problems.
     
  9. stihl_collector

    stihl_collector ArboristSite Operative

    Joined:
    Jul 10, 2010
    Messages:
    195
    Likes Received:
    12
    Location:
    Qld Australia
    I tune eveything slightly on the rich side, never had a problem with any 2 stroke we've ever had.
     
  10. porsche965

    porsche965 Addicted to ArboristSite

    Joined:
    Oct 3, 2008
    Messages:
    1,967
    Likes Received:
    1,969
    Location:
    N.E. Ohio
    A all the Way.

    However most shops use a tach to specs. ??

    I use a tach to establish a baseline for the particular saw. IF you haven't had any problems all these years don't change what you are doing.

    :cheers:
     
  11. Scooterbum

    Scooterbum Addicted to ArboristSite

    Joined:
    Oct 30, 2006
    Messages:
    4,877
    Likes Received:
    1,033
    Location:
    Virginia
    I run mine a little rich. 4 stroke out of the cut and in till I make the saw work.

    I don't want to hear it clean until it's under a load.

    I'd just rather not take the chance on damage.I hate seeing aluminum transfer in a saw I like.
     
  12. oscar4883

    oscar4883 Addicted to ArboristSite

    Joined:
    May 16, 2009
    Messages:
    2,043
    Likes Received:
    204
    Location:
    PA
    :agree2:
     
  13. biggenius29

    biggenius29 Banned

    Joined:
    Sep 21, 2008
    Messages:
    2,290
    Likes Received:
    269
    Location:
    Hamilton Michigan
    Thats what I do. My saws are all work saws. I would rather them run a little rich and a touch slower, than lean and fast. Whats .01 seconds worth when you are cutting firewood?
     
    miking likes this.
  14. kugss

    kugss ArboristSite Operative

    Joined:
    Apr 26, 2010
    Messages:
    353
    Likes Received:
    45
    Location:
    Pittsburgh
    Sounds like me.
     
  15. dingeryote

    dingeryote Blueberry Baron

    Joined:
    Nov 21, 2008
    Messages:
    13,604
    Likes Received:
    2,273
    Location:
    Michigan
    Same here.

    If it cleans up with just a light load, it's too lean in my book.

    I don't like to wear out the carb screws with daily fussing, and temp and fuel variations can grab ya when you aren't paying attention.

    Stay safe!
    Dingeryote
     
  16. Cliff R

    Cliff R Addicted to ArboristSite

    Joined:
    Jan 24, 2008
    Messages:
    1,920
    Likes Received:
    795
    Location:
    Mount Vernon, Ohio
    Good responses, and yes, it's best to er slightly rich than lean, in all cases.

    I've been cutting firewood since the mid-1970's, and have never smoked a P/C yet, or had any other engine "issues" related to lack of lubrication, EGT's, etc.

    What throws a monkey wrench into this deal is that some modern saws have rev-limiting coils and retard modules. These items can mimic the "four stroking" that we listen for at no load, and the untrained tuner can end up too lean with the "H" screw and possibly damage the engine.

    I have a couple of saws with rev-limiters. I start out with them noticably rich, and missing heavily, then sneak up on the tune by leaning them up and making cuts. With some, it's still difficult to tell exactly when you hit the rev limiter vs the ideal fuel setting(s).

    For all my other saws, I set them for best power in the cut, and so they four stroke when the load is removed. They should "clean up" as soon is load is applied again. Basically, the "H" speed screw is your "rev limiter", and makes sure saw gets plenty of fuel to avoid going lean or running away when the load is removed.....Cliff
     
  17. mowoodchopper

    mowoodchopper Polar Bear

    Joined:
    Jan 3, 2009
    Messages:
    2,405
    Likes Received:
    216
    Location:
    to far west for the preacher
    #1 If you run your saws this way, you have a problem even with a 5100!
     
  18. Arrowhead

    Arrowhead RARE BREED

    Joined:
    Feb 26, 2009
    Messages:
    13,842
    Likes Received:
    3,603
    Location:
    Illinois
  19. Hedge Hacker

    Hedge Hacker ArboristSite Operative

    Joined:
    Aug 20, 2010
    Messages:
    101
    Likes Received:
    10
    Location:
    Illinois
    ok now im worried. i put a muffler mod on my new 460 and took it in to the dealer to have them adjust the carb. i know that they just hooked her up to the tach and tuned it to 13.5k. It flat out screams. do you think its running too lean?
     
  20. teatersroad

    teatersroad What's a henway?

    Joined:
    Nov 22, 2009
    Messages:
    2,276
    Likes Received:
    456
    Location:
    Central Oregon
    A then C here, though not really timed cuts, I just know the saw well enough that if I'm not getting the performance I expect I look to the tune. This generally leads to a quick deuche of the air filter too. Seems after mod the saw is more sensitive to wanting all of that air.

    Could someone give a simple explanation of why the saw runs leaner under load? Or does it?
     

Share This Page