Best way to tune a Carb...?

Arborist Forum

Help Support Arborist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Geal

ArboristSite Operative
Joined
Mar 30, 2009
Messages
111
Reaction score
5
Location
UK
has anyone got a simple but effective way of tuning a carb, i have had a look on here but havent had much luck, does any one know of a good link or site thanks.
 
Geal

All you really need is a good straight knot free log and a stopwatch.

An 'H' setting that gives you the best timed cut is your best bet.


Set the 'L' for the best idle , quick and smooth acceleration, with out loading up on extended idles will be all you need.


There is a ton of info using the search function.

Welcome to the site! :cheers:
 
has anyone got a simple but effective way of tuning a carb, i have had a look on here but havent had much luck, does any one know of a good link or site thanks.

Just run both screws in until they just touch the seat, don't go to far. Now Back them both out 1 1/4 rounds and it'll be so close it ain't funny then fine tune it by ear. Good smooth idle and four stroking at WOT.

If the saw has a muffler mod. be sure to richen up the high speed to allow for it. Saw Safe.
 
Just run both screws in until they just touch the seat, don't go to far. Now Back them both out 1 1/4 rounds and it'll be so close it ain't funny then fine tune it by ear. Good smooth idle and four stroking at WOT.

If the saw has a muffler mod. be sure to richen up the high speed to allow for it. Saw Safe.

+1 for most carbs.......a very good starting point.
 
Just run both screws in until they just touch the seat, don't go to far. Now Back them both out 1 1/4 rounds and it'll be so close it ain't funny then fine tune it by ear. Good smooth idle and four stroking at WOT.

If the saw has a muffler mod. be sure to richen up the high speed to allow for it. Saw Safe.

Yup. This is how I tune my saws. Might not be scientific but I haven't burnt one up yet.
 
so from what i have read L for the right mix and H for rpm, so if i turn up H clockwise to get more rpm for my saw will i have to adjust the L? and if i get my saw to idle smoothly with the L needle then just adjust the h needle for the rpms? is this right?
 
so from what i have read L for the right mix and H for rpm, so if i turn up H clockwise to get more rpm for my saw will i have to adjust the L? and if i get my saw to idle smoothly with the L needle then just adjust the h needle for the rpms? is this right?

Not exactly. Lo and Hi typically operate independently. Once saw is warm turn Lo screw counterclockwise until saw starts to stumble. Then turn clockwise until same thing happens. Midway between both were you set Lo screw. Now you set idle screw. Test settiings by seeing whether saw revs smoothly w/o stumbling. Next you set Hi speed as discussed in earlier posts. However don't lean out too far(turn clockwise) or you'll burn up saw. I listen for fourstroking sond and then rev saw up and shut it off under WOT. This way I can check color of plug. You're looking for a light brown color. If its more white in color your Hi speed needle is set too lean. Turn it counterclockwise and retest.

Bob
 
Not exactly. Lo and Hi typically operate independently. Once saw is warm turn Lo screw counterclockwise until saw starts to stumble. Then turn clockwise until same thing happens. Midway between both were you set Lo screw. Now you set idle screw. Test settiings by seeing whether saw revs smoothly w/o stumbling. Next you set Hi speed as discussed in earlier posts. However don't lean out too far(turn clockwise) or you'll burn up saw. I listen for fourstroking sond and then rev saw up and shut it off under WOT. This way I can check color of plug. You're looking for a light brown color. If its more white in color your Hi speed needle is set too lean. Turn it counterclockwise and retest.

Bob


thanks for that will try on my 361
 
The l is the low speed/ idle jet and the h is the high speed jet.

How I tune a saw is warm it up then turn in the idle screw till the chain spins, then tweak the l screw till you get the spot where the chain spins the fastest. From there blip the throttle and adjust for best throttle response. Turn the idle screw out till the chain stops and/ or to manufacturers recommended rpm (if you have a tac.)
H you hold the saw wot and richen (turn out) the h screw till it burbles. Put the saw in wood, make some cuts and richen/ lean slightly for fastest cutting. If you're really extreme adjust the h while the saw is in the cut, lol.
 
Set it to stock settings and go from there. Put it in wood and listen. It is pretty obvious what the saw wants. If you are unsure on this take it to someone who knows and will teach you. A good dealer or someone on this forum who is local to ya.
 
Back
Top