I wonder if that is the 'older' style rods though? I have been using the newer one for a long time and never had a problem. I only ran for a short time on the old style rod. It would be interesting to see if any of the newer I beam style rods have exploded. I guess the difference for me is if the rod does let go, my boat just stops and i fish it out. If a rod goes in your plane, it's a totally different story! If i do ever happen to have it let go on me i'll let you know here but i'd say with the RPM's i'm pulling you're pretty safe going higher on the new style rod. Although i've probably jinxed myself now....

i have also heard of the crank flexing and causing interference with the head in these (being that they are only a half crank engine). I am yet to see any evidence of this.

The next engine i am close to having a go with is one from a Pope brand Blower vac. 26cc cross flow, full crank, pull start and at AU$87 from the local department store it's a reasonable option for a cheap boat. The only thing that puts me off is that it is a slant plug style so it is harder to water cool. Next to useless for a plane though. If i build up another boat, i might give one a shot.