I have been reading all the threads on the Norvel engines, particularly the 25's. There have been several posts about the lack of consistency in performance. I was wondering if they (Norvel) have worked out the bugs from the earlier engines. Like most others, I am contemplating the OS 25FX or the Norvel Big Mig 25. I want an engine that will be hot, light, and reliable. If Novel has worked out the problems and the support is there, I would love to give one a try.

I've been around both at the field and the 25FX has been less tempermental and easier to get parts for. It's a toss up as to which has more power

Most problems with Norvel engines appear to be from lack of break-in. All the advice I have read said to bench run them for an extended period. How many tanks of fuel escapes me at this moment.

I have an .061 and .15, both bushed and have run about a 1/2 gallon through each. They are very reliable and quite powerful. Considering that the Norvel has a 5oz or so weight advantage on the 25FX, the Norvel could be down on power and still be the better choice.