ORIGINAL: dennis
The problem is that they seem to have so many problems. Especially with heads and carbs. Not to mention the Fox 74 when introduced years ago I carefully broke mine in and was pleased with it until I flew it about a dozen times and the piston holed itself on a less than full power run. Fox explaining cavalierly that they had somehow cast the pistons with too thin a crown and they had a problem. Sure they fixed it for free but it has sat in my drawer going on 20 years with no thought of running it as I moved on to other engines. I can certainly relate other problems over the years but most manufacturers have also had their share of duds. To Fox mfg. credit though they do stand 100% behind their product.
There have been many improvementin the last couple of decades. Especially with the carb and heads. OS never really owned up to the many bearing issues they have, at least Fox admits when they have a problem and fix it for free. Lifetime warranty in fact. I have a Fox .50 made in the 80's, original bearings, no problems as long as you keep the nitro low. One of my fav engines, despite the crude needles.