031AV Stihl issue(s)...

[mrcaptainbob]

It runs pretty good! My son replaced the carb and all rubber hoses.
I believe he also put in an electronic points system. It's back to it's old reliable startup self.
However.....I cannot get it to rev past 941++ rpms. Should be maxed at 12K. Can't get there.
I'm thinking it's the pick-up that may need adjusting. Timing is at .008-.009. I'll verify that tomorrow.
After doing some minor cutting for maybe 5/10 minutes, anytime the trigger is released quickly it does a smallish 'pop' through the exhaust. By the way, compression's in the 140 range. It idles great, no chain creep.
Now...on to the oil mix.
for some reason, I always thought Stihl was 50:1. Did a quick check today for that rpm thing and found the oil mix spec'd at 40:1
So???? Since I run 50:in all my Stihl's, should I stay there? Or be safe at 40:1? Don't want to clog anything up.
(I cut about 14 cords a year for the house owb....)

[sawguy21]

Is it an aftermarket ignition system? The electronic spark may not be advancing far enough. Also check the spark arrestor, it may be plugged.
Regarding the mix, you are opening a can of worms. That saw is 50 years old, 24:1 was the norm at the time. As technology improved mix was cut to improve performance and reduce the smoke. My newest saw is 30 years old, I haven't had any problems with 50:1 using modern oils but many like to go heavier as they feel more comfortable.

[mrcaptainbob]

Yes, it's the old oil mix 'issue'. My own is to follow manufacture's desire. Regardless it's age.
I'll check with my son as to what ignition he installed.
Thanks for the help, Sawguy.