Hi Folks, the good news is I've got rid of the old Tomos Engine, the bad news is I somehow ended up with another 2 stroke ok it was cheap its a yamaha 20hp autolube jobby from early 90's.
All was fine when I picked it up and saw it running now its home and on my boat it seemed to want to stall at low revs.
I've taken the sparkplugs out and given them a good clean and although this helped it still wasn't quite right
A chap in the marina near me suggested I needed to up the idle revs which I did and I've adjusted the air mixture screw and it doesnt stall now but still seems a tad lumpy. Any ideas ? is there a trick to setting the mixture?
Yamaha are notorious for blocked idle jets which somehow screw the whole range of operations.
My advice - strip and clean with carb cleaner and an airline, pay particular attention to the little piercings in the choke tube on the engine side of the butterfly, you can trace their location by following the jet-way tubes moulded into the carburettor casting.
However - if it doesn't respond to a good clean the chances are that aluminium salts have blocked the jet-ways and to sort that problem requires some drastic operations involving prising out the little balls that are peened into them and re-boring, followed by sealing up the external holes again with lead pellets.
NOT for the faint-hearted! Plus you need a decent workshop to undertake that trick.
The cost of boating is insignificant compared to costs of a young wife and two teenage kids!
Lumpy at low revs
Posted - 25 May 2012 : 22:16:31
