It seems that I had similar dilema to resolve some time ago and I made my mistakes. Just to share what I learned:
1. McCulloch 28cc from leaf-blower turns APC 17x6W at 8000-9000 rpm and weight above 1.5-2.0 kg with magnet
depending on how much "flesh" one cuts from the body.
Replacing the magnet at this small(!) gas engine seems not efficient because the battery is not much lighter than
the flywheel, similar is for Zenoah etc. and needs care to be charged while the flywheel is "permanently charged".
Using a starter is not such a bit deal; most of us have it and use it unles the engine is so well tuned...
2. For each type engines there is an OPTIMUM displacement and word 'optimum' here is going to cause unger if not
clarified; it is quite personal "optimum". For me ALL BOILS DOWN TO POWER-vs-WEIGHT Ratio unless there are too
many personal other reasons:
A) Glow Engines have their optimum at 26cc developed for F3A. Below that they are a bit too heavy and above that
they eath too much fuel (about 2.5 times more than gas ones.).
B) Gas Engines seems to have some optimum at about 80cc. 50cc is still too small and 100cc gets a bit too big.
After experimenting with toooo many engines I am about to try to sell most of them and retain the only 26cc
and to not invest in 80cc-gas - it is leading to too much Side-Costs (model, servos, Car to transport it, and the
Smell to save it at home is a problem beside the Fire hazard which is pretty much there when gas is involved.)
C) My side"-menu" has bunch of 15cc and few 35cc all glow.
Surely my Gas McCulloch will have ot wait till I play enough with the Glow ones and they are not so "oily" if
pipe is taken to out of the tail of the engine. Surely I also like the simiplicity of the Glow - that is why so many
are with Glow...
Well, I will appreciate if someone tells more technical reasons why one should go gas if he wants to stay on
modest budget ?
Cheers, Nick