So bought a chinese saw (holz g070)

[fields_mj]

I'll preface this by saying that I've never owned or operated an 070, 090, or any of their clones. On my high jet, I open it up until it 4 strokes at WOT out of the cut. In the cut, it should not 4 stroke. If it does, I lean it out a little until it stops 4 stroking in the cut. I presume that these lower RPM models will still 4 stroke just like other saws. Of all of the ways people have said to tune the hi jet on a carb, this is the way that makes the most logical sense to me.

I don't worry a whole lot about the mfg max rpm specs because my saws haven't had much work done to them (most have not had any work done), and my saws rarely see max RPM because I make it a habit of trying not to run the saw wide open outside of the cut. The vast majority of the time that my saws see max RPM is while I'm tuning the carb. Otherwise its in the cut where I'm not going to be able to hit those max RPM ratings. If I'm tuning a new saw, I may set it a little under the max recommended RPM during break in but that's about it.

Then again, I'm not a builder and I may blow up one of my saws tomorrow.

 

[sliceoflife]

Something is mechanically wrong, you should be able to bog the crap out of that saw with the high jet.

Yeah honestly I don't know what to tell you, low and idle jet adjustments are both super responsive. High jet I have completely unseated and it's just hanging on by the little orange bracket that keeps it from falling out... still 7800 rpm with WOT. Can't find anything obviously wrong, but just seems that the high adjustment doesn't do much, if anything, beyond 1-2 turns out.


Fields, thanks but I dont trust my ear to identify 4 stroking while cutting and trying to adjust the jets... just beyond my comfort level with the saw at this point. Maybe in the future.

 

[Vintage Engine Repairs]

The fact it runs is something to be pleased with honestly! Though, I agree with maintenance supervisor, it doesn’t seem right.

 

[Maintenance supervisor]

Mines an 090 butyou can hear the "growlly burble " of 4 stroking out of the cut after tune.

 

[sliceoflife]

Kind of the jackhammering or really loud velcro tearing sound @ 2:22-2:23? Right when the pull cord handle starts having a seizure?

 

[sliceoflife]

So I milled a slab on my lunch.


Started it and let it warm up for three minutes... Soon as I put the saw to wood it bogged down from 7800rpm to 3500 rpm and stayed there.

I turned in the H adjustment until it started to sound like it was overrevving to my (VERY uneducated and probably wrong) ear then backed it down slightly and milled.

This was sitting mostly at 6000-6500 with occasional dips into 3500-4000 and spikes to 7000-8000 when it came out of the wood. Chain was getting fairly dull (fourth slab I've done without sharpening), so could that have been causing excessive load and causing this? I'm going to sharpen the chain before the next cut anyway, but out of curiosity.

Still it Seemed to mill ok at this. 8ft of 16-20" diameter silver maple took about 10mins to cut a slab, going slow at a Very awkward angle (it was laying on the ground)... probably if it was set up better, could have been done in 5-8min.

Based on tuning videos I've seen, it shouldn't just sit at max RPM no matter where the H adjustment is when unloaded & WOT; should it? Any clue what might be causing this?

All told nothing seems to be wrong enough with the saw to keep it from working but so far:


1. Decomp valve crappy, doesn't stay open about 90% of the time; so I just hold it down when pulling and release at the top of the pull.
2. Clutch lets chain spin @~ 1500 rpm... 1000 rpm under spec for idle. Luckily chainsaw idles ok @ 1500... but still.
3. RPM seems fairly erratic under load... 3500-6500 RPM
4. RPM sits at 7800 @ WOT with no load no matter where the H adjustment is set (It'll go over 7800 if I turn the adjustment WAY in, but won't go below 7800 no matter how far out).


Will probably be a bit before I get the chain sharpened and mill another slab, but I'll set up to record when I do so I can post it and yall can hear the audio and let me know if it gives you any insight.

 

[sliceoflife]

So I had another hour free after work today and slabbed out another slab... Total length 17 min because there was another log in my way so first foot took a long time wiggling it around; then a neighbor approached me and I assumed he needed to talk (he just wanted to watch), then I ran out of gas 4/5 of the way through the log. Also I'm pushing it slightly uphill and on the ground... so really poor planning for the cut; but hopefully you can hear the saw. Peaked at the Tachometer when the saw really was roaring and it was bouncing around 7000 and peaking at 9000 or so; but mostly sticking at 7000-7500. When I was feeding it into the log I could tell it was bogging quite a bit from the sound (I'd guess 4000-6000); but didn't have a free hand to maneuver the tachometer so I could read it at this angle.


Uploaded... So Here I start it. Try to show the RPM (compression of video made it illegible, but it was ~1500), then rev it a few times before setting it up (around 3min mark) and trying to figure out how to work around a log that the nose of the mill was hitting for a minute or two before milling.

 

[Maintenance supervisor]

The decomp is meant to be held down on these, it doesn't stay down on its own.

 

[sliceoflife]

Really... good to know, thanks

 

[Burning man]

Did you check the governor? It's an airflow operated governor that controls the throttle position and is located above the flywheel, it is a thin chintzy piece of metal.

 

[sliceoflife]

Governor looks good... seems to function correctly.

 

[OM617YOTA]

So I had another hour free after work today and slabbed out another slab... Total length 17 min because there was another log in my way so first foot took a long time wiggling it around; then a neighbor approached me and I assumed he needed to talk (he just wanted to watch), then I ran out of gas 4/5 of the way through the log. Also I'm pushing it slightly uphill and on the ground... so really poor planning for the cut; but hopefully you can hear the saw. Peaked at the Tachometer when the saw really was roaring and it was bouncing around 7000 and peaking at 9000 or so; but mostly sticking at 7000-7500. When I was feeding it into the log I could tell it was bogging quite a bit from the sound (I'd guess 4000-6000); but didn't have a free hand to maneuver the tachometer so I could read it at this angle.


Uploaded... So Here I start it. Try to show the RPM (compression of video made it illegible, but it was ~1500), then rev it a few times before setting it up (around 3min mark) and trying to figure out how to work around a log that the nose of the mill was hitting for a minute or two before milling.

Gave it a listen, sounds pig rich to me. You say above that it'll go above 7800 rpms if you turn the high speed adjustment WAY in, and I suspect that what you're thinking of as WAY in is actually where the normal adjustment should be. Keep in mind that a good starting point is ~1.5 turns out from seated(gently!), and you probably won't have to go past 2.5 or 3 turns out to be right. Don't get hung up on how many turns out or what RPM to run, the ear really does tell the story.

I'm by no means an expert, hopefully someone who is will tune in.

 

[OM617YOTA]

@sliceoflife

Go to the 2:30 mark on this video. When he gets on the throttle, for just an instant you can hear the burble or the extra pops that sound like yours does the whole time, then he puts it in the wood and it smooths out immediately. This is what you're looking for.

Mines an 090 butyou can hear the "growlly burble " of 4 stroking out of the cut after tune.

 

[holeycow]

Rich all over from bottom to top. Wow! Turn those screws in! It's miraculous that it even runs.




oh ya, toss the tach in the dumpster.

not really, but it is entirely unnecessary.

edit; doh! He mentions tach... double doh! He doesn't even search for the burble..liability problem obviously. He does a real one. This is not it. Damn. Sorry.

 

[holeycow]

 

[holeycow]

Both of those guys know exactly what to do, but complicate things too much. I'm disappointed in Steve. He does a much better video on tuning.

there's a million of them. There's only one correct sequence. Once you are familiar it is second nature and you might skip a step. But to learn you should follow the sequence exactly.

anyway, the saw is WAY rich. I don't know that saw, but most older designs will start and run pretty good with both mixture screws turned out 1 to 1 1/4 turns out from lightly seated. Fine tune from there.

new saws are simply a pita with epa restrictions, limited coils, computer tuning and whatnot.

 

[OM617YOTA]

Rich is good. If it's going to be tuned wrong, that's how you want it tuned. Kept it from burning down halfway through the first slab.

Go new enough and the saws are dead easy to tune......

 

[holeycow]

Ya, like between 1975 and 2005 or so..

the 070 in question is making very little power..

but don't burn it up either.

 

[holeycow]

Yeah honestly I don't know what to tell you, low and idle jet adjustments are both super responsive. High jet I have completely unseated and it's just hanging on by the little orange bracket that keeps it from falling out... still 7800 rpm with WOT. Can't find anything obviously wrong, but just seems that the high adjustment doesn't do much, if anything, beyond 1-2 turns out.


Fields, thanks but I dont trust my ear to identify 4 stroking while cutting and trying to adjust the jets... just beyond my comfort level with the saw at this point. Maybe in the future.

You need to turn that high back in. Just set it a hair rich from factory specs and see how it runs. Or not. One thing for sure, that saw it rich as hell on top.

ok, I listened to more of the audio video. It's painful to hear. Your saw is hating life. Try turning that screw in a quarter turn. There are brief moments where it stops four stroking, so you are not real far off...well you are, but go to the correct tune slowly. If that was a small saw it would stop dead in its tracks. And for gosh sakes, hold the throttle wide open! You don't run a saw at part throttle openings. Hardly ever.

I don't know about your saw, but the two chinese saws I bought recently are refreshing in their tunability. The react just how a saw should react. None of my newer ones are that easy because they all have limitedcoils and stupid carb settings and need attention more than any of my older, pre-epa saws with respect to tuning.

love the birds in your audio, btw!

 

[holeycow]

Ok. Watch this video.