G'day Harry
I still have the original vacuum control button without a hole that is fitted on the motor housing and is connected to the Diaphragm Carby Cap vacuum line connector still on.
So it seems to like to start in the run position only.
Does having a Vacuum Control Button without a hole effect the way it starts.
Also I ran the lawn mower for 1/2 hour and tested its RPM and Compression. RPM was 3660 RPM and Compression was about 60 PSI.
I tried to restart the Lawn Mower on Run and it started after the Second Pull.
This time I ran it for another 20 minutes and its RPM was about 3820 RPM and Compression was about 55 PSI.
Again I started the Lawn Mower on Run and it started after the Second Pull.
This time I ran it for another 30 Minutes and its RPM was about 3660 RPM and compression was about 53 PSI.
So having a Vacuum Control Button without a hole affect the way it starts, and does the above RPM and Compression readings , still warrant a Piston Ring Replacement. I am happy to do it , if it will help compression & starting. Also to replace the Vacuum Control Button with one with a hole.
Harry
If the vacuum is not connected to the carby diaphragm the governor won't work ,I wouldn't worry about it
on an old 160 2 stroke as they usually have enough power anyway.
I can't find a Victa factory lowest compression in psi recommendation to replace the rings ,but this
is the one a shop has already said is too low and I recommended about 70 psi cold as the lowest I'd use,
Honda 4 strokes recommend 85 psi cold as the lowest .
Low comp can mean hard starting and easily stalled under load.
Victa give a maximum used piston ring gap at 16 thou and with new rings the mimimum ring gap is 8 thou.
A Victa 160 full crank motor has it's maximum torque figure at 2000 rpm ,I haven't looked at Power torque
figures but it just shows you don't need to scream the motor out normally to cut grass unless compression is down.
I always start the Power torque mower on full throttle and back it off when it starts.
Having a Vacuum Control Button without a hole won't affect the way it starts.
I'd put rings in this one just because it's down a fair bit ,other 2 stroke are recommended for a rebore
with 8 thou bore wear from standard.
A full crank 160 victa is 8 thou clearance maximum between the piston skirt and bore before
needing a rebore so I'd use that figure for the Power torque motor.
To check the ring gaps you push the rings evenly down the bore from the top by about an inch.
You can spend $30. on this one or get another mower or just use it until it won't go any more,
up to you.
Cheers
Max.