woops sorry brad ,yer both experts I follow
Chainsaw Tuning 101
- Thread starter blsnelling
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Good call from Brad. I had a 372 doing the same thing. It was worse right after a fill up, not as much air space in the tank. It would have "moments of glory" as it leaned out right before starvation set in
Glad I didn't mess it up. I knew better than to keep running a saw with issues....
Hmm the half choke or half throttle position (or how you want to call it) doesn't work anymore. It doesn't open up enough. Read a lot what the problems could be, but can't fix it. It is a stihl ms240. Any suggestions? It is a mechanical problem, saw runs good.
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HusqyStihl
ArboristSite Guru
Good call from Brad. I had a 372 doing the same thing. It was worse right after a fill up, not as much air space in the tank. It would have "moments of glory" as it leaned out right before starvation set in
Luckily it only happen twice so far, first time i figured "crap, walked all the way out to the wood to cut and didn't fuel her up", walked back, found it had fuel in it but not much so i was scratchin my head. Topped everything off and started right up and ran fine. Idled all the way back to the wood, rev'd fine, WOT fine then a minute into the cut and it crapped again. Not gonna run it again until i get a valve in it for reassurance. Sounded the same as you just described! Thank again!
~Moose
Hmm have some problems with my husqvarna T435. It starts good, and idlrs good. When you rev it up it goes very good. Also when you saw it also goes very well. I pruned a whole tree and has plenty of power. But when it is on idle and you hit the throttle 3 or 4 times in a row it just dies. What can cause this? I was thinking about the L screw?
I also have a video if you don't understand what i mean.
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I also have a video if you don't understand what i mean.
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VinceGU05
PSA vitim.
A tad rich I would say.
Edit: definitely too rich on the L. Screw it in 1/8 of a turn and try again. And repeat.
If it flat spots, it's too lean [emoji106]
Edit: definitely too rich on the L. Screw it in 1/8 of a turn and try again. And repeat.
If it flat spots, it's too lean [emoji106]
Is it possible that one of the symptoms of running it too rich that the muffler is full of oil? I use Aspen 2 stroke mix.
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VinceGU05
PSA vitim.
It will burn out if tuned right and you use it a fair bit to get some heat into it.
DrewUth
Jack of all trades, master of none.
In my experience, tuning the H is fairly easy; its the Low speed that I fiddle with the most. For example, I want the saw to respond promptly when I whack the trigger open; too lean and it will bog, to rich and it will blubber and slowly clean out. On the flip side however, after I chop the throttle from wide open, occasionally my saw will stall, which is pretty frustrating. I richened it up, but then I have to fiddle with idle settings to get it to idle properly. Thoughts? Clean air filter of course, good fuel mix, etc.
Does anyone still read plugs? I grew up racing two stroke dirtbikes, and a plug reading was always key, but its tricky to read for High and for Low.
Does anyone still read plugs? I grew up racing two stroke dirtbikes, and a plug reading was always key, but its tricky to read for High and for Low.
NewShockerGuy
ArboristSite Lurker
Great thread!!
I am in the process of tuning my echo cs-370. I noticed that it starts right up. I have de-catted the muffler, opened the exhaust port and now need to adjust accordingly.
For the low side I noticed that when I adjust either lean/rich, I can make the saw dance more on the ground... meaning it will vibrate a lot more, OR I can adjust the low side to where it doesn't dance on the floor. Is there a preferred method or just adjust the low side according to the throttle response and make sure it's instant, but not continuing to spin the chain after I let go of the trigger... IE: It should not turn the chain without throttle. And after I let go it should come to a stop rather quickly and not spin down...
High side I am making a little rich, but it's very difficult for me to hear the 4-stroking and or burrble... I am cutting into wood but natually when I let off of cutting it changes in pitch, but I can't tell if it's good pitch or bad pitch. I doesn't scream like it's too rich in the one video but it also doesn't burrble... so I should make it slightly richer?
Thanks!
-Nigel
I am in the process of tuning my echo cs-370. I noticed that it starts right up. I have de-catted the muffler, opened the exhaust port and now need to adjust accordingly.
For the low side I noticed that when I adjust either lean/rich, I can make the saw dance more on the ground... meaning it will vibrate a lot more, OR I can adjust the low side to where it doesn't dance on the floor. Is there a preferred method or just adjust the low side according to the throttle response and make sure it's instant, but not continuing to spin the chain after I let go of the trigger... IE: It should not turn the chain without throttle. And after I let go it should come to a stop rather quickly and not spin down...
High side I am making a little rich, but it's very difficult for me to hear the 4-stroking and or burrble... I am cutting into wood but natually when I let off of cutting it changes in pitch, but I can't tell if it's good pitch or bad pitch. I doesn't scream like it's too rich in the one video but it also doesn't burrble... so I should make it slightly richer?
Thanks!
-Nigel
Always err on the safe side and go richer. Then slowly lean it out until it cleans up in the cut.
nomad_archer
Addicted to ArboristSite
Nigel - The second video in the first post is the best one to hear the 4 stroking as a result of being too rich. If you arent hearing the 4 stroking go richer until you do. It Doesn't hurt to go way rich and slowly lean it out until it cleans up in the cut.
For the low side adjust for good throttle response and that the chain comes to a stop when you let off the throttle. Use the idle adjustment to smooth out the idle and to keep the chain from rotating on idle.
For the low side adjust for good throttle response and that the chain comes to a stop when you let off the throttle. Use the idle adjustment to smooth out the idle and to keep the chain from rotating on idle.
NewShockerGuy
ArboristSite Lurker
Thanks for all the info!
Let me update as I just got back from the woods.
I started it out on the high side RICH... Meaning when I gave it full throttle it would garble and almost die. I guess this is TOO right, yes? So I started backing it out slowly. Each time slowly adjusting and listening. One thing I am not sure about and I didn't see it covered in here. What does it mean when I am cutting the wood probably 8" in diameter, and after I am done with the cut and bring it back up as if I am normally resting it dies. Still too rich? It did NOT do this everytime, just once in a while..It did this to me a couple times right after it was done cutting. I could however pull the rope and it started back up no issue.
Thanks,
-Nigel
Let me update as I just got back from the woods.
I started it out on the high side RICH... Meaning when I gave it full throttle it would garble and almost die. I guess this is TOO right, yes? So I started backing it out slowly. Each time slowly adjusting and listening. One thing I am not sure about and I didn't see it covered in here. What does it mean when I am cutting the wood probably 8" in diameter, and after I am done with the cut and bring it back up as if I am normally resting it dies. Still too rich? It did NOT do this everytime, just once in a while..It did this to me a couple times right after it was done cutting. I could however pull the rope and it started back up no issue.
Thanks,
-Nigel
nomad_archer
Addicted to ArboristSite
Nigel I'm not sure what the cause could be. You may want to create a new separate thread. You will get more response's to your question.
I do! Also super important is to read the wash on the piston top. The plug will tell you quickly how things are, but if you really want a fine-tune then you have-to-have your saw completely and thoroughly warmed, then run it in the wood at least 45-60 seconds at the appropriate rpm's then shut it off using the kill switch. Let it cool then look at the top of the piston. It should be black, somewhat "dry" in appearance, with scallops at the transfers where the incoming mix has "washed" the carbon off. You can Google for photos.
If it gets too hot, like right before you are going to burn something, you'll see what appear to be bright shiny specks on the piston dome. Those are droplets of melted aluminum coming from the top of the piston or combustion chamber; you are at the ragged edge.
I spent almost a whole winter season trying to wring out a Holtzman ATACC on my '99 XCR 800 before I gave up on the ATACC and removed it. Called Holtzman and they told me the product doesn't work very well on flat-slide carbs!
Here's a video I made this afternoon demonstrating how to tune a chainsaw that has a rev limited ignition coil. On a saw like this, you can tune these by ear listening for it to 4-stoke. The rev limited kicks in before it gets to that RPM. It's very difficult to tell if your hearing the rev limited kick in or it it's 4-stroking. This is how you do it.
Not stockI see Spring has Sprung in Franklin, Oh.
That saw can't be stock
Sounds really good
