My new conversion of the G62 weighs only 4 lbs and has syncro spark electronic advance..Pretty hard to get much lighter without making it too weak somewhere...I can make the prop hub a little lighter, might try one this week...It be UNDER 4 lbs including ignition, which is as always, inside the mount...
An engine under 4 lbs with 26-28 lbs thrust can't be too much of a problem...