Stihl 070 stalls in cut

[Robin Wood]

Hey guys i have a stihl 070 that stalls in the cut, the engine does not die but the chain takes a good bite on the wood midway while cutting and the chain stalls. Im cutting hard dead wood btw

saw has:
1. new clutch(old ones had bluish mark)
2. new crank seals(old one was hardened on one side i think it was clutch side)
3. new fuel line, tank vent, impulse hose, fuel filter and etc
4. new ignition coil, new plug wires, new plug
5. carb rebuilt new diaphragms
6. cylinder got fine sanded and smoothened out
7. piston had a lil scoring below oil ring and ring
had a lil wear but still usable(according to my dealer)

any input are appreciated, thanks in advance

 

[scallywag]

Bar/chain size?

 

[watchamakalit]

Is the oiler functioning? Will the chain immediately spin when removed from the wood after it stalls?

 

[Robin Wood]

it has 30" new b&c(cutting dry acacia, aussies might be familiar with this)
clutch cover side smoked when bar was buried and i stopped when cut was finished
the auto oiler is a lil stingy but im spamming manual oiler though
its kinda hard to pull the saw from the wood, its like 1 cutter teeth has drived in real good and wont let go
i have to give it good yank to release it(imagine if raker set too low and chain grabs)
yes it does, high rpm is strong and throttle response is unbelievably good
idling becomes weak once hot
plug is rust colour but edge and thread tad oily, mix is 50:1 low smoke good oil

 

[scallywag]

It almost sounds like the log is closing on your cut?.........I have a few 070/090, Contra saws, they are not designed to run on 50:1!.......But thats your call.

 

[watchamakalit]

I wonder if it's leaning out in the cut and losing power.
Rakers too low making it take too big of a bite?

Not really sure just spitballin.

 

[Robin Wood]

scallywag: im starting to think that you could be right. its expensive oil and designed to be mixed 50:1, any more oil it will flood the engine. i have used it on my brush cutters and other saws, got good result but i do have cheap oil that i mix 20:1, reckon i use that instead ?

watchamakalit: shouldnt the engine die when leaning out in the cut ? anyway imma try richen it and give it a test first thing tomorrow mornin. the chain is new i have not filed it yet, it happened on the very first cut and following ones

 

[scallywag]

Have you tuned this saw yourself?.. If so where are the high and low adjustment screws on the carb set at?.......they both should be one full turn out from seated.

More oil will not flood your saw.

 

[scallywag]

With carb set correctly, mix 25ml of your good oil to one (1) litre of fuel=40:1 and try the saw.


Personally, I run my seldom used 070/090 saws on 25:1. But as I said, it's your call.

 

[Robin Wood]

No my dealer did the setting, HL screws are on the left side of the carb right above the gas cap
Yeah it wont flood but will sure make the plug wet and gunk up the exhaust port
I have tried mixing more of the good oil before for brushcutters but the engine struggles to run at high rpm
Come to think about it my dealer used the cheap oil mixed at 20:1 when doing the carb setting, i will go back to that and see how it reacts
BTW when you mix more oil per fuel/l shouldn't it rob more power ?

 

[scallywag]

Your saw must be tuned to the mix ratio for best performance!...Can you buy Stihl oil where you are?.....You need to keep the fuel mix at least 40:1 or better still 32:1.

 

[scallywag]

Robin, I think you have found your problem!......your saw is tuned to 20:1 and you're running 50:1 fuel mix

 

[pioneerguy600]

070`s and 090`s are not like the other saws in the Stihl lineup of chainsaws, they are designed for much heavier duty cutting delivered at lower RPM., more oil actually makes more power in slower revving engines. Listen to scalleywag, he really knows these saw very well and the conditions you are cutting in.
I will ask one question, is the governor still set up and working in your saw?

 

[Robin Wood]

no doubt you guys are pro's
you know you dealing with pro's when they ask questions in alien language
it cuts much better with 20:1 mix
governor aka autochoke is hooked on but cant tell for sure if its working without opening the shroud and giving it a race
it does sound a tad lean on the high side(wot)
it cuts extremely well and 4-strokes on 1/2 throttle

 

[Robin Wood]

stihl oil are red ones right ?
its kinda expensive, but we have similiar quality cheaper versions that everybody uses
echo has its own oil and some loggers say its the best
i tried pouring few drops of this good oil in a cup of the usual cheap oil and it went right in to the bottom, cant this be used as a guideline to see if its good oil ?

 

[Robin Wood]

sorry minor correction mix was 25:1 not 20:1

 

[scallywag]

no doubt you guys are pro's
you know you dealing with pro's when they ask questions in alien language
it cuts much better with 20:1 mix
governor aka autochoke is hooked on but cant tell for sure if its working without opening the shroud and giving it a race
it does sound a tad lean on the high side(wot)
it cuts extremely well and 4-strokes on 1/2 throttle

Robin, Ok lets stay with the 25:1 fuel....... Your saw should be 4 stroking at WOT out of the cut only!

Do you have a work shop manual?

 

[Robin Wood]

yeah i should stop messing around the oil/fuel mix
yes i notice that being said alot times in the forums
however my dealer sets a lil lean on the high side, i will try richen all my saws
maybe dealers set saws a lil lean so it wont last too long ?

 

[Steffen]

I use Aspen gas in all my Stihl saws, but mix it to 3% with the best oil.
The saws run very well on this, and the Aspen fuel cleans the engine also.

 

[Robin Wood]

mind if i ask what is Aspen ?
anyway the saw tends to cut one side now when buried in the log(bar 30" log 34"), chain still looks new and needs no sharpening so far(ran only 1 tank of gas with it)
bar still looks alright(still new and also ran 1 tank of gas)
otherwise it cuts good on the small stuff, did lotsa cookie with 1/2 throttle and it cuts like a dream could go on n on lol