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#Post#: 66270--------------------------------------------------
Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Chris-PA Date: December 12, 2015, 5:37 pm
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I have a 38cc Earthquake, which is a Chinese clone of a RedMax
G3800 - only they modified it to meet emissions. It's kind of
an interesting contrast given that this is the saw Zenoah
started with to make the strato GZ4000, and this is the
alternate non-strato approach to meeting emissions. It had
modified port timing, lower volume transfers runners and a cat
(think Echo and others). So of course I ported it and got rid
of the cat muffler for a modded normal one, but I could never
get the thing to rev like I wanted. I went through maybe 4
different tear downs, cut the jug, swapped the ignition to a
Ryobi system and back again, swapped the carb and back again.
That whole adventure was documented here:
HTML http://www.arboristsite.com/community/threads/what-i-learned-porting-an-earthquake.270735/
I hadn't used it in a while, but was out cutting since it was in
the 60's today and decided to run the Earthquake. And.....it
was a slug. Well maybe that's extreme, but it still just didn't
want to rev and the spool up was lazy. That's been the
persistent issue with this build, and while you can convince
yourself it's pretty good, if you let it sit for a while and run
other better saws it's pretty apparent when you pick it up
again. So I took it down to the bench and yanked the jug.
The first obvious thing was that it's been a head slapper.
There were two spots in the casting of the combustion chamber
under the spark plug boss that looked like they slumped a
little, and I had tried to grind them out when I decreased the
squish, but they looked to have been just kissing the piston
dome - maybe just enough to polish the carbon. So that had to
be dealt with, which I did by grinding some more on those spots
in the the combustion chamber, and by a little filing on the top
of the piston. I also filed off the orientation arrow which
they had cast on the piston crown, as it had left a neat little
dent in the edge of the squish band! Which shows that using
solder to measure squish in a couple of spots isn't necessarily
good enough, especially with a domed piston.
But the main thing was the transfers. If you look at the
pictures of the transfers I showed earlier (
HTML http://www.arboristsite.com/community/threads/what-i-learned-porting-an-earthquake.270735/#post-5157085<br
/>), I had only ever raised the intake side outlets (and the
intake side transfers are quite small on this jug). From what I
have read they should be even, or the exhaust side ones should
open first. I was pretty convinced this has been the problem.
So I took some measurements and cut some card stock, and just
hacked away with a small ball end cutter until I evened them all
up. It wasn't that pretty, but not that bad either. I left the
total transfer duration at 106 (21deg blowdown).
So I slapped it back together and took it back up just before
dark - and finally it has the snap I wanted! I even took some
of the extra spark advance out I had put in to try to get the
rpms up. So all the stuff I tried - compression increase,
squaring up the intake, spark advance, opening the lower
transfers, opening the muffler more - none of it really
addressed the sluggishness problem. Those mods may have helped
it to run like it does now, but but without fixing the transfers
it wasn't good enough. Which of course I had been told.
I'll try to get a video of it now - it's finally what I expected
it should be.
#Post#: 66279--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: 3000 FPS Date: December 12, 2015, 8:03 pm
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Good deal Chris. It was a good read. I am not a big fan of
the earthquakes but I know you love to tinker with these saws
and figure things out so good for you.
#Post#: 66281--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Chris-PA Date: December 12, 2015, 8:46 pm
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Thanks! Really I'm a fan of Zenoah designs, and the clones are
a way to get older models cheap. Actually this saw was
purchased as a parts mule for my GZ4000's for $35 delivered -
but I've been playing with it ever since!
#Post#: 66300--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Chainsawrepair Date: December 13, 2015, 11:29 am
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Never ran the copies. But the ported 3800 redmax was super light
and nimble for 38cc.
HTML http://chainsawrepair.createaforum.com/redmax/redmax-3800/msg444/#msg444
#Post#: 66308--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Chris-PA Date: December 13, 2015, 3:54 pm
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Ran it a bit clearing brush and bucking a bit of ash. Throttle
response was nice while cutting brush. Took this video:
HTML https://www.youtube.com/watch?v=B-12jcD7DYc
Once it got loaded in the cut it was running around 10,500rpm.
Seemed to run pretty clean - at least I didn't stink too bad
like exhaust after running it today.
#Post#: 66353--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: weimedog Date: December 14, 2015, 12:34 pm
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A great read, thanks for posting. :)
#Post#: 66354--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Chainsawrepair Date: December 14, 2015, 1:22 pm
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[member=1697]Chris-PA[/member] have you figured out why the
copies weigh so much more then the redmax 3800 originals?
Sounds and looks good in the cut. Wonder if you could make the
chain hungrier. :P
#Post#: 66357--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Chris-PA Date: December 14, 2015, 1:50 pm
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[quote author=weimedog link=topic=5469.msg66353#msg66353
date=1450118081]
A great read, thanks for posting. :)
[/quote]Thanks!
[quote author=Cut4fun . link=topic=5469.msg66354#msg66354
date=1450120945]
[member=1697]Chris-PA[/member] have you figured out why the
copies weigh so much more then the redmax 3800 originals?
Sounds and looks good in the cut. Wonder if you could make the
chain hungrier. :P
[/quote]I don't think do weigh much if any more than the
originals. My G621 clone weighs under 12.5lb, or withing 0.1lb
of the original if what I've seen is true. I never weighed the
Earthquake, but it's lighter than my GZ4000's by a little, which
is about right. The difference between how much mag is in the
alloy might make a small difference, but the alloy part of the
G3800 chassis is so small it would barely be noticeable.
The chain was Tri-Link lo pro semi chisel. I had touched a rock
with it cutting brush earlier, so it had just been filed and the
depth gauges set. That was a 16" bar on a 38cc saw cutting a
pretty hard piece of ash - I feel like that was all it's got and
a more aggressive chain would just bog it.
#Post#: 66362--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Cut4fun Date: December 14, 2015, 2:18 pm
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[quote author=Chris-PA link=topic=5469.msg66357#msg66357
date=1450122649]
[quote author=weimedog link=topic=5469.msg66353#msg66353
date=1450118081]
A great read, thanks for posting. :)
[/quote]Thanks!
[quote author=Cut4fun . link=topic=5469.msg66354#msg66354
date=1450120945]
[member=1697]Chris-PA[/member] have you figured out why the
copies weigh so much more then the redmax 3800 originals?
Sounds and looks good in the cut. Wonder if you could make the
chain hungrier. :P
[/quote]I don't think do weigh much if any more than the
originals. My G621 clone weighs under 12.5lb, or withing 0.1lb
of the original if what I've seen is true. I never weighed the
Earthquake, but it's lighter than my GZ4000's by a little, which
is about right. The difference between how much mag is in the
alloy might make a small difference, but the alloy part of the
G3800 chassis is so small it would barely be noticeable.
The chain was Tri-Link lo pro semi chisel. I had touched a rock
with it cutting brush earlier, so it had just been filed and the
depth gauges set. That was a 16" bar on a 38cc saw cutting a
pretty hard piece of ash - I feel like that was all it's got and
a more aggressive chain would just bog it.
[/quote]
Thats what I was wondering how it would do with a PS PS3 chain
on it. You got any to try?
#Post#: 66365--------------------------------------------------
Re: Finally Have My Ported Earthquake G3800 Clone Running Right!
By: Cut4fun Date: December 14, 2015, 2:27 pm
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Just trying to save some paper weights listed. Paper weight
listed for 5000 is accurate as I owned one.
G3800AVS 9.1lbs
GZ400 9.7
GZ4500 9.6
GZ4000 9.5
G5000AVS 11.2
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