RE: 90 sized engine recommendation
You can get a Magnum .91 fs on RCU market place for under $150.00 new. Been flying Magnum 4 strokes for a few years now and they are very good engines . Best bang for the money.
ST .90 can be hard to set up , but once dialed in , run very good.
You really donthave to spend alot of moneyto geta good engine.