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Recommended RPM for tuning

Started by AlaskaLes, November 02, 2016, 02:08:46 PM

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AlaskaLes

I've got a cool new tool for the chainsaw shed.
Been reading a lot about using a tach to tune chainsaws lately.
I've always used the tune-by-ear method in the past and they run well.
Nowadays, we're putting a lot of hours on the saws and I like to get the most out of the tools.  Both power and longevity.
So, I ordered one of the more recommended brands of tach.  It's an Oppama PET 1100R.
I liked this design, because it can be used on every motor I own.

My questions here is for the guys who use tachs to tune.
What are the high RPM settings for these saws?
Husky 353
Husky 394XP
Echo 330-T
Thanks for your help.
You can see Mt McKinley from our backyard...Up Close!!

Mighty Mite MK 4B, full-hyd, diesel bandmill
Kubota 4wd 3650GST w/FEL; Forks;
3pt Log Arm& Log trailer
Husky 394XP
Husky 371XP
Husky 353
Echo 330T
Nyle 200M
Robar RC-50 50BMG-just in case the trees get out of line

joe_indi

Coils with speed limiters and/or electronic ignition timing advance result in tach reading errors. With more electronics going into the coil including chips to control the carb, the only reliable tuning aid will be our ears.

There is also word of a fuel injected MS661 (?) undergoing field trials.
What role our tach will have in the future of such saws is unknown.
But definitely, those two flaps on either side of our heads should continue to act as aids to let us know if our saws are running okay  :D

AlaskaLes

Interesting Joe...I will continue to utilize the provided flaps.
The one good thing is that all of these are 2006 or older, so the high tech gadgets should be a non-issue.

The Echo was my 1st test of the tach.  I hooked it up and it was topping out at 13,500 to 14,500.
My first thought was that this was too high.
Looked it up and it's right on the money!!  My flaps were working on that one!! 8)

I posted this question thinking that the Recommended RPM would be more difficult to find for these saws.
It was surprisingly easy to locate the numbers.
Toady I'll be checking the other 3 saws to see if they are in need of some tweaking.
You can see Mt McKinley from our backyard...Up Close!!

Mighty Mite MK 4B, full-hyd, diesel bandmill
Kubota 4wd 3650GST w/FEL; Forks;
3pt Log Arm& Log trailer
Husky 394XP
Husky 371XP
Husky 353
Echo 330T
Nyle 200M
Robar RC-50 50BMG-just in case the trees get out of line

ZeroJunk

Make sure they are up to operating temperature.

joe_indi

Clean air and fuel filters and recommended bar and chain are needed prior to setting the recommended rpm. Also ensure your seals are holding (will need a vacuum test). If you use the tach, the best setting would be to do it in the wood, where, at times you might need to open up the H screw instead of closing it.

Al_Smith

The ear makes a better instrument than a tachometer .Things like altitude and temperature will vary how you tune the engine .Manufacturers recommendation of max RPM are only a guideline not a hard fact that must be adhered to .If you err it's better to be on the rich side as opposed to lean .

CTYank

Used to be, before the days of cheapie inductive tachs, that mfgs' instructions for (H) carb adjustment was to go for max rpm under load (in the cut). That is it- good as it gets.
Without a tach to measure that, the "2-stroke under load @WOT, and start of 4-stroking when you lift" approach does the same, and just requires functioning hearing, no electronics.
Setting by tach, again, is just an approximation, keeping things quick, cheap & dirty for dealers. IMO.
'72 blue Homelite 150
Echo 315, SRM-200DA
Poulan 2400, PP5020, PP4218
RedMax GZ4000, "Mac" 35 cc, Dolmar PS-6100
Husqy 576XP-AT
Tanaka 260 PF Polesaw, TBC-270PFD, ECS-3351B
Mix of mauls
Morso 7110

AlaskaLes

More excellent replies!!
I really like the variety of experience here.
You can see Mt McKinley from our backyard...Up Close!!

Mighty Mite MK 4B, full-hyd, diesel bandmill
Kubota 4wd 3650GST w/FEL; Forks;
3pt Log Arm& Log trailer
Husky 394XP
Husky 371XP
Husky 353
Echo 330T
Nyle 200M
Robar RC-50 50BMG-just in case the trees get out of line

SawTroll

The manuals I found said 12,500 for the 394xp, 13,000 for the 353 and 13,500 for the 330T.

Keep in mind what the others said though, those numbers aren't a goal by themselves.

It also happens that the recommended max rpm changes during production of a model.

At least coil mounted rpm limiters will mess up the readings (and what the ears tell you) when the limiters kick in. This means that final tuning of the "H" should be done by starting a bit low on the rpm (where you get a normal reading and sound), and "creep up".

Also it happens that saws run the best (and are tuned right) on higher rpm than the max spec - and then it is of course up to the owner to decide how to handle it...
Information collector.

ZeroJunk

A tach is just a tool. Not a bad idea to check your ears occasionally. I always end up a few hundred RPM below the max rating, and leave them that way. What a few hundred more RPM gains you is meaningless to me for my use. And, you have no control over what fuel, temperature ,etc. that customers are going to subject it to. So, if you send a saw out the door tuned to max RPM you are nuts IMO.

AlaskaLes

Makes sense, just shy of max RPM isn't going to be a huge power loss and it would tend to be a safer range to run it hard.
You can see Mt McKinley from our backyard...Up Close!!

Mighty Mite MK 4B, full-hyd, diesel bandmill
Kubota 4wd 3650GST w/FEL; Forks;
3pt Log Arm& Log trailer
Husky 394XP
Husky 371XP
Husky 353
Echo 330T
Nyle 200M
Robar RC-50 50BMG-just in case the trees get out of line

Kbeitz

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

three feathers

I am with Zero Junk on this. I set my saws about 300 below max. no load rpms.
Jerry

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