084 setup

[charlieh]

i have just finished checking over my new to me 084av and i have some questions, the saw is running a 36inch bar and the exhaust has had some moddifications performed on it (about 6 small diameter holes in the front cover) i have had the exhaust off and the piston and cylinder seem to be in reasonable condition (very very slight scoring on the exhaust side of the piston). The saw is running the non rev limiting coil.

The high screw was set to 3/4 of a turn out and WOT was 10050 rpm, i set it back to 1 turn out and was getting 8400rpm so is the more turns out richer or leaner? (richer i assume)

I have red threads about this saw turning 12000 rpm ok, i dont want to aim for that as the saw is for milling so 10k is ok with me, I was advised by the previous owner to run it at 25:1, surely stihl 50:1 which is recomended in the manual is ok for this? or should i run a richer mix?

also in the few seconds i had it running on the tach the cylinder head seemed to get very hot my next biggest saw is a 372xp and i havent noticed this level of heat so is this heat normal?

any help is always appreciated (im still a relative newbie)

Charlie

 

[nytreeman]

might be running to lean creating the heat or mix may be wrong.How old is the saw my 051av is mid 70's and takes 40:1.I have a 372 and 272 husky and there both air injected for better intake airflow and cooling

 

[carvinmark]

I run my 084 at 50:1 on my mill with no problems.

 

[Lakeside53]

two things...

1) For milling you should definitely run a mix heavier than 50:1. Milling is a continuous power operation (unlike the intermittent power use of cross cutting) and is typically a full tank at full power, then refuel). Additionally, the saw need to be "detuned" slightly (richer mixture) to limit the peak HP (to keep the piston temperature down). The heavier mix and detuning will help the lubrication and temperature issues. Use a full synthetic mix 32-40:1. 50:1 is fine for non-milling operations.

2) Before you start believing your tach, you need to determine whether your saw has a limiting coil or not. The tuning procedure is quite different between the limiting and non-limiting versions. At 3/4 turn out I suspect your saw was pulling 12k... but your tach reads low because the limiter is skipping sparks.


8500 is way too low (RICH) in any case... I'd be comfortable at 11000-11,500 for milling.

 

[charlieh]

hi, thanks for all your help, i will get some richer fuel mixed up for milling

lakeside, the saw has the non-limiting coil so i figure the reading of 10k rpm at 3/4 of a turn out was correct, i wonder if something else is causing it to rev low considering the h jet setting, would the exhaust mod cause this?

charlie

 

[Lakeside53]

Nope... If anything it would be the other way...


I'd check your carb inlet needle for leaks, and that your adjustment screws / seats aren't damaged. If they are, your "1 turn" calibration can be off.