What kind of tachometer do you use to set the rpm of you rev limited saws? Can you change the battery in it or is it a throw away?
I'm using a TT20K, from Design Technology Inc. (http://www.tinytach.com/design/handheld.php). It has a replaceable battery, and a 1/2 second refresh rate, very important for tuning a saw. It has other features as well. It had the most bang for the buck of any tach I looked at. Beware of tachometers that use a 2 second refresh rate, you may do damage before you get a reliable rpm reading.
I have the EDT8 from Stihl, one of the slickest tools I have ever used. No replaceable battery but it just keeps going like the Energizer bunny.
Get a .5 refresh rate tach. The 1.5 sec refresh rate from Baileys and EDT 7-8 are to slow for the money. There is a cheapie tach that is 2.5 sc refresh rate and cost $20-$25, it works, accurate but is slow.
Older no longer available tachs like the Stihl EDT-5, DET-302, DET-303, Echo-1000 (same as EDT-5). If you find one grab it.
Still available TT-20 are all .5 refresh rate and cost $85
If I couldnt find a EDT-5 like I have, I would buy one of these new.
http://www.amickssuperstore.com/DTI_2_Cycle_Two_Stroke_Tachometer_Tach_p/dti%20tech-tach%20tt-20k%20tach.htm
Any body using the "Tiny Tach", the $65 one?
We had them on our mowers before they started putting hour meters on them. They worked well, however they do not have replaceable batteries, that I know of. It also looks like you will need the Commercial TinyTach, which will read to 20,000 rpms. The standard TinyTach only goes to 9,999, and has a really bad (for chainsaws) refresh rate of 2.5 seconds.
I was wondering the procedure you use to set the high speed jet? Madsen's show the rpm for my 372/rev limited at 13500 rpm. This is very close to the rpm were the limiter cuts in. Do you start over rich, then sneak-up to 13500 on the counter? The problem I see is the refresh time on the counter/tachometer, you could jump to the rev limiters rpm and not know it.
That is the way I would do it but I still have a lot to learn. ;D
Set it at 13000 instead on the edge of burning up in a long hard cut. It'll have better grunt set a little lower. Steve
On a rev limited saw the tach will jump around when the saw is on the limiter. Like on my Dolmar 7900 rev limited at 13.5k, if hitting the limiter it would show 11.8k 12.3k 11.6k 12.9k 12.1k 11.7k 13.0k, hope you get the idea.
I just tuned at about a 100 below max rpm, but I was readjusting for weather changes all the time with mine. When it got cooler I would have to adjust, even colder adjust, warms back up adjust.
You can also tune them in the wood during the cut if you wanted to for some reason, just watch not going to lean. Yes it will hit the limiter out of the cut.
Assuming good fuel and better mix,lean grants long life.
I set jets in a cut and pay attention to what my spark plugs tell me....................
I hear reports of saws burning down quite often from being set to lean,and it's been worse lately when they are set to EPA spec or higher and then do some long hard cuts. Just because they really scream out of the wood when set lean doesn't mean they cut faster, I've found they bog easy when too lean, given a little more fuel they have a wider powerband. I've never heard of one buning down from being too rich but if way too rich you'ld lose power and carbon up more. Steve
Quote from: ladylake on February 14, 2009, 04:31:52 AM
I hear reports of saws burning down quite often from being set to lean,and it's been worse lately when they are set to EPA spec or higher and then do some long hard cuts. Just because they really scream out of the wood when set lean doesn't mean they cut faster, I've found they bog easy when too lean, given a little more fuel they have a wider powerband. I've never heard of one buning down from being too rich but if way too rich you'ld lose power and carbon up more. Steve
Wise words to listen to smiley_clapping. Rather be rich then to lean cutting firewood all day. I didnt get the lean is a long life thing either and i have run some saws lean before, just not for firewood cutting. 8)
As per always,consider the source.
Tough to get giddy over the "experience" of someone cutting a cord and thinking it telling.................
For conversation,this powerhead had over 8 million board feet under it's belt at the time. Far from from running rich and compromised with less than pristine fuel,due to logistics. She spins like a top,even when pulling a 42".
But cutting for money,do in fact sway things.....................
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