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Oleo-Mac GS720 and 820

Started by joe_indi, September 24, 2008, 10:03:49 AM

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joe_indi

Has anyone tried out the new saws GS720 and GS 820 from Oleo-Mac (Emak or Olympik)?

http://www.oleomac.it/Sezione.jsp?idSezione=520&idSezioneRif=375&titolo=New%20GS%20720%20-%20GS%20820%20chain%20saws

I have one of each for trials and would like a second opinion.

Joe


sawguy21

I remember selling and servicing O-M saws in the 70's but have not seen the brand for many years. I believe some models may be re badged for other manufacturers.
old age and treachery will always overcome youth and enthusiasm

SawTroll

Quote from: joe_indi on September 24, 2008, 10:03:49 AM
Has anyone tried out the new saws GS720 and GS 820 from Oleo-Mac (Emak or Olympik)?

http://www.oleomac.it/Sezione.jsp?idSezione=520&idSezioneRif=375&titolo=New%20GS%20720%20-%20GS%20820%20chain%20saws

I have one of each for trials and would like a second opinion.

Joe



After looking at the specs, I see absolutely no reason to invesigate any further - power to weight obviously isn't good at all........ smiley_chop smiley_chop
Information collector.

tyb525

LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

SawTroll

Information collector.

tyb525

Yea I know that's what you said, when he said he had them for trials I thought he meant he could try them for free, which in that case why wouldn't you.
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

joe_indi



Quote from: SawTroll on September 24, 2008, 08:21:59 PM
After looking at the specs, I see absolutely no reason to invesigate any further - power to weight obviously isn't good at all........
That was exactly the way I too felt at first.
But as tyb525 commented, since the offer was to try them for free, why not?

You can never know about them for certain unless you have tried them.
Would you try them if the power to weight ratio were to change a bit.
I asked that question because that is exactly what I am trying to find out.
The engines are built like real work horses.The bore and stroke specs give promises of potential power, but when actually cutting wood these saws were behaving like toddlers. I was using  18" guide bars on them with chains from Carlton (A3), Stihl (35RSC) and Oregon (73LGX).
18" full chisel is what we run on MS460, MS660, 372xp, 385xp and 575 here.
I am trying to figure out why the O-Mac saws are not pulling their loads like these other saws with similar specs.

tyb525

Less compression? maybe the clutch doesn't have enough friction? Different muffler?
LT10G10, Stihl 038 Magnum, many woodworking tools. Currently a farm service applicator, trying to find time to saw!

joe_indi

Quote from: tyb525 on September 25, 2008, 10:33:37 PM
Less compression? maybe the clutch doesn't have enough friction? Different muffler?

Compression is fine.Clutch too is okay.
I don't think it's the muffler. Exhaust flow is too smokey and oily.
If I try to lean the mixture the engine does not rev up.
It four strokes too muck.But setting the H screw leaner did not help.
I does not seem to be getting the  required rpm.
It bogs down in the cut.
Since fuel supply and compression seem fine, I will have a look at the ignition.These saws have digital ignition  ::) with variable timing.
Will post later
Joe

olyman

somethins flucky!! as olys nearly always haul mail!!!! and will last forever if not abused--

joe_indi

The culprit was the ignition module.
It was the bit about the variable timing that got the  ole gray matter into top gear.
Logically variable timing would mean retards at slow speeds and progressive advance as the rpm increased.
This works on automobiles, but maybe not on chainsaws.
When the saw is at load in a cut,the rpm is sure to drop.This causes the ignition timing to become retarded.Which causes the rpm to go down further, which causes the timing... well, it keeps going down to the bottom end.The engine becomes sluggish.Unless you lift the bar out of the cut and let the rpms build up again.
I would say that this seems to be a tedious way of doing a simple job.

To confirm my theory I needed an ignition module without any fancy electronics that could be used in the space, with the available mounting points.
The only one at hand that fitted the bill was the module of the Stihl 420 blower.
I selected the 70cc GS720 for my experiment.
The results were to be seen(and heard) to be believed.
The engine response improved nothing less than 200%.
The initial carb settings seemed to be too rich with the module change so I leaned out the carb adjustments.Boy did she respond then!!
Though it might seem to be an exaggeration, honestly, the revving was better than that of a MS460.
I tried the saw in a few cuts and it went straight down without any noticeable drop in rpm.
Since I had no way to take an extensive trial, I gave the saw to one of my customers and told him to push it however much he could.He uses both MS460 and Husky 575. That was on Friday (25th).
This morning he called me up to tell me the results.
Since it left the 575 at the starting post, he did his trials with only the 460 and the 720.
For every 2 trees the 460 cut the 720 cut 3. The 460  completed 25 tons(metric) of cutting per day  to the 720's 30 tons. The 460 needed 10 liters of fuel per day while as the 720  managed with 8 liters.
The 720, probably because of the greater surface area on the cylinder fins, ran much cooler.
And remember that the GS720  has only 70plus cc against the MS460's 76cc.

I repeated the module change on the 80cc 820 an hour ago.
It is showing what I think is is same improvement in engine characteristics.
I  called up the supplier who gave me these saws for trials and   asked him to get me 2 'no-nonsense ' ignition modules from Oleo-Mac.
I want to check out whether all this happens only with a Stihl blower module or whether it holds true for any other module.
Joe



SawTroll

Quote from: tyb525 on September 25, 2008, 04:14:15 PM
Yea I know that's what you said, when he said he had them for trials I thought he meant he could try them for free, which in that case why wouldn't you.

Nothing wrong with it then, and the results he posted sure are interesting!   :) 8) 8)
Information collector.

jacob j.

I've always liked the Oleo-Mac products but these models still appear to have some drawbacks-

1.- Single-sided brake handle- prone to breaking off under heavy use as compared to the dual-sided brake handle as found on other big saws

2.- The nylon air filter would be a drawback here in our extremely dry and dusty summer time environment.

3.- The rev-limiting ignition which Joe has had good luck replacing with a non-limited module.

4.- It appears from the brochure that these still have external clutches?

It's been my experience that the Oleo-Mac/Olympyk saws have been well made and are high quality units, even if slightly heavier.


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