My 020 AVP started to show some strange symptoms.
The L screw was quite far out, the H far in and transition between the two was poor.
I tried a new carb kit and that didn’t help, took the welch plug out of the L side expecting it to be full of debris, but that was clean and finally tested the high speed nozzle ball valve.
Using the Mityvac showed how it would leak down, sometimes gradually, sometimes quickly. It would still open and close, but the seal was ineffective.
I tried cleaning it in an ultrasonic cleaner, tried forcing it against its seat with compressed air and spraying carb cleaner through, none of which helped.
I did some research to find that they are hard to find for the old Tilly carbs and NLA in Australia.
I checked alternative carbs for the same model saw to find the Walbro nozzel valve / jet appeared (in photos) very similar. I went out on a limb thinking that there was (though only a very small chance) a possibility they are interchangeable, but worst case scenario it’s $10 Australian to find out.
It arrived today and it measured 0.5mm wider in diameter and tapered.
I decided to chuck it up in the drill press and place some abrasive paper onto a piece of float glass as a flat backing.
After about 45 mins I finally got it to within 0.01-0.02mm of the OEM Tilly.
I put a very thin coat of clear nail polish to take up any imperfections and seated it home.
Sprayed carb cleaner through the H side to remove any debris and put the saw together.
Tuned it and it was great. I could close the L 1/4-1/8 of a turn more than before because it wasn’t sucking air through the nozzle and the H was able to be richened up by 1/2 a turn more as it wasn’t running so rich off the L.
Transition was clean and unrestricted too.
All in all it was a fantastic result, couldn’t be happier and what I figured probably wouldn’t work, did so on a number of occasions.
The L screw was quite far out, the H far in and transition between the two was poor.
I tried a new carb kit and that didn’t help, took the welch plug out of the L side expecting it to be full of debris, but that was clean and finally tested the high speed nozzle ball valve.
Using the Mityvac showed how it would leak down, sometimes gradually, sometimes quickly. It would still open and close, but the seal was ineffective.
I tried cleaning it in an ultrasonic cleaner, tried forcing it against its seat with compressed air and spraying carb cleaner through, none of which helped.
I did some research to find that they are hard to find for the old Tilly carbs and NLA in Australia.
I checked alternative carbs for the same model saw to find the Walbro nozzel valve / jet appeared (in photos) very similar. I went out on a limb thinking that there was (though only a very small chance) a possibility they are interchangeable, but worst case scenario it’s $10 Australian to find out.
It arrived today and it measured 0.5mm wider in diameter and tapered.
I decided to chuck it up in the drill press and place some abrasive paper onto a piece of float glass as a flat backing.
After about 45 mins I finally got it to within 0.01-0.02mm of the OEM Tilly.
I put a very thin coat of clear nail polish to take up any imperfections and seated it home.
Sprayed carb cleaner through the H side to remove any debris and put the saw together.
Tuned it and it was great. I could close the L 1/4-1/8 of a turn more than before because it wasn’t sucking air through the nozzle and the H was able to be richened up by 1/2 a turn more as it wasn’t running so rich off the L.
Transition was clean and unrestricted too.
All in all it was a fantastic result, couldn’t be happier and what I figured probably wouldn’t work, did so on a number of occasions.
