My synopsis of the matter, if its Says "Balanced and blue printed" it means beware.

There is a natural tendency in the human being to explore and experiment. So many people cannot wait to disassemble their engine or to change something about it. Many times it is just for the sake of change. Many times the results are more like how much better your automobile runs after you wash it.

If you try to trade in a car or truck on a new one, If the dealership gets the impression you modified it from original, they will not take it at any price.

The same goes for a model engine. I've been looking at model engines for close to 60 years and some people foul them up royally.

There are some people (also on RCUniverse) that I would trust if they were selling a model engine. But just someone out of the blue - I would let it pass . . .

I bought a OS 48 four stroke. The guy said that he had ported and polished it. He did do a nice job of blending the valve pockets into the runners and matching the intake runner to the intake manifold. It even had a OS 52 carb. I had previously seen some of his Harley work so I figured he didn't foul it up. The OS 48 did run nice with no problems but didn't have any more noticeable power than a regular OS 48.

I see a lot of modified model engines on the Internet. Some are modified just for the sake of change. Some of the mods serve no real purpose in performance and may possibly be detrimental to overall operation.