Echo 680 "H" needle tuning?

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LuDookie

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Hi everyone,
Seeking some advise....
I've got a fairly new, couple months old Echo CS680 that I've done a fair amount of cutting with so far. The saw has been great and hasn't given me the first problem, and cuts good, but I did notice something while getting it tuned in, and then stumbled upon some information on a thread here on AS that leads me to bring this up...I've read here about guys running 590's and them having a semi-fixed jet that will allow the saws to run with the H needle fully seated, not allowing the operator to lean them out enough in some circumstances. I live at nearly 9000 feet ASL, so everything runs a little fat up here. I always expect to have to lean things out. When I first cranked my 680 and began to break it in, it was definitely fat and sluggish, and "4 stroking" heavily at WOT. I began cutting with it and slowly leaning it out in the cut, gaining RPM's and strength to the point that the H needle is fully seated (and yes, the limiters have been defeated). The good thing is, the saw is very strong at this setting, even though I've backed it off a bit, and when you open the H needle the RPM's drop and so does the cutting strength. I also pulled the muffler and see signs of a rich run, and a very good looking piston, so at least I'm pretty sure I'm not lean. I'm running a tach on the saw and seating the needle gives me just above 12,000 RPM's WOT and anywhere around 7,000 - 9,000 cutting, only burbling a little when the RPM's raise in the cut (less pressure)....so, I'm liking the performance but here's my questions....

Does the 680 have the semi-fixed jet? It will definitely run pretty strong at 9,000 feet with the H needle seated.

I hear some responses to the 590 threads suggesting a rev limiter, but will a rev limiter come into play at cutting speeds? Seems like the burble I'm hearing(in the cut) at about 9,000 - 9,500 is "4 stroking". I am under the impression that the rev limiter is at max RPM if this saw has one....which leads to the next question....

Does the 680 have a rev limited coil?

I've had really good luck tuning and running a CS370, MS261, 385XP, and an old Pioneer, along with my weedeater and blower. The 680 is the first one to "bottom out" on the lean side. Fortunately I like where it's at, and it's better than being "bottomed out" on the rich side. And for the record, so far it is the coolest running gas powered tool I run now. I'm pretty sure I'm not toasting the saw, but I know you guys on here have a lot of knowledge on the subject.

Just looking for some reassurance, I guess.

Thanks in advance.
 
My 680 took a little getting used to. This saw is more low-end power than speed. Almost fools you into thinking something is wrong with the tune. We tend to get used to the high-rev saws. This saw is more about torque. I really like mine.

Sent from my E6782 using Tapatalk
 
Yep, I'm pretty used to the way the Echo's run, and it's just a solid feel. The 680 can keep lugging at 5 to 6K long enough for you to adjust and keep it from stalling. It's that torque that is a little reassuring that it's not running lean, not to mention that everything has trouble breathing up where I'm at, so it's hard to get anything too lean.
 
Definitely an old-school feel with the 680. It's a little heavy but built like a tank.

Sent from my E6782 using Tapatalk
 
Out of a service data booklet for the 680
View attachment 619412
What stands out there is the operating speed....9,500 to 10,000. I'm typically getting over 9K but the band is all over the place when you are noodling and cutting big stuff, which I would expect. The new manual doesn't mention that. It states the max RPMS from a range of 12,500 to 14,000, which is quite a range. Same thing for the manual on the 670, and I've heard they run best at about 12,000 to 12,500. I'm only getting 13,600 or so with my MS261, and it is screaming. I honestly am not interested in getting my 680 close to 14,000.

Thanks for that. Wish I had a better understanding of the ignition timing data.
 
I edited my OP a little....I misspoke and meant to state that "operators aren't able to lean them out enough", not richen them. Sorry for the confusion.
 

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