Rpm tunning

[Eric howes]

I have a 266se and just got a new tach and wanted to dial in the saw. Problem is there is 2 different spec that I found. One that is for a 266se with is 12500 free and 8300 on a load. The other spec I found is 12500 free and 9300 on a load. My 266 says SE and xp on it so I'm not sure why the load difference . Does anyone have any insite on this?
Also, how exactly is the load rpm done? I can see there being alot of variations in load rpm running. Should I set the free rev rpm and call it good?

 

[John Stryker]

I would set it to 12,500 wot, and then see how it does in the wood. You could see if richening it a little helps with the load rpms, but the rpms will vary depending on how much load you put on it which complicates things.

 

[ZeroJunk]

Make sure you run the saw until it is up to operating temperature before you set it with a tach. They will creep up as the saw gets warm and any excess fuel in the crankcase is burnt out. Even then I would fudge a few hundred RPM on the max no load.

 

[Eric howes]

Ok, I also have a partner 5000. Specs say 14000 free. Saw seem to run pretty good with good power but once I put the tach on it, it won't even free rev 14000.

 

[blsnelling]

You can't tune to a specific RPM under load. There are WAY too many variables that affect that RPM.

 

[tomdcoker]

I bought a $150.00 Tac when I first started working on saws and have not used it in ten years. There is a thread on tuning by ear that bsnelling posted several years back, sorry I do not have a link, but someone should be able to send it to you. Tom

 

[Eric howes]

You can't tune to a specific RPM under load. There are WAY too many variables that affect that RPM.

That's what I was thinking as well.

I can tune by ear, but I like to get the spec rpms and the dial it in from there. I set the 266 to 12550 but to me still seems in the rich side

 

[Marley5]

I favor the rich side vs the lean side and how i tune. Ymmv

 

[ZeroJunk]

I don't think they ever intended for you to try and tune it under load with a tach, just a spec as to where it has optimal performance. Probably no way to do that other than a dynamometer.

 

[jltrent]

I would get it hot and set for around 12000 rpms and go with it. I have a DTI 20K fast tach and it is amazing how close I can get by ear and then check with the tach.

 

[ChoppyChoppy]

tunning?

 

[holeycow]

Jetting is like making hay.

Once you know/understand the subject, a tach or a moisture meter are completely unnecessary

IMO

 

[Deleted member 149229]

Jetting is like making hay.

Once you know/understand the subject, a tach or a moisture meter are completely unnecessary

IMO

Not when you have substantial hearing loss from 40 years in heavy manufacturing.

 

[holeycow]

Yes, I suppose. But familiar saws tune can also be felt. Not so much with unfamiliar saws.

I hope I can continue without a tach, although it might be an interesting exercise just to see where a saw really is.

 

[Evan]

Ive never used a tac. Not really sure what theyre good for but they seem to be veey popular here.
Guys want me to put my cummins on the dyno. Im like why i dont really care if the number is 250 or 500hp its gets the job done i need it to do

 

[Finnrpm]

There is a thread on tuning by ear that bsnelling posted several years back, sorry I do not have a link, but someone should be able to send it to you. Tom

https://www.arboristsite.com/community/threads/chainsaw-tuning-101.250802/

Just wondering why above thread is not in Chainsaw stickies?

RV

 

[SawTroll]

I don't think they ever intended for you to try and tune it under load with a tach, just a spec as to where it has optimal performance. Probably no way to do that other than a dynamometer.

Yes, the "under load" number is the rpm where they expect the max power to be - it is just for information, not for tuning.

12,500 rpm is a fairly conservative "max WOT" rpm number, so I wouldn't be afraid to go a bit higher if the saw still "four-cycles" out of wood.

 

[Okie]

https://www.arboristsite.com/community/threads/chainsaw-tuning-101.250802/

Just wondering why above thread is not in Chainsaw stickies?

RV

very good. (tuning by ear and listening for the 4 stroke rich area) If saw won't 4 stroke. it's time to find out why, before a meltdown occurs and meltdown can happen very fast when under a heavy load.

 

[JTM]

After playing with a tachometer on my 660 I no longer need it to tune. My ear has been calibrated for that saw.

 

[Eric howes]

I have a variety of different saws so it'll be nice to know