Simple V4 engine is here.

[karl_1052]

Originally Posted by goof2

Those are weak examples. I'll bet the Mercedes/Ilmor pushrod engine from the 1994 Indy 500 redlined north of 10k rpms. That also has about as much to do with a production engine for the street as what you posted.

Well, those are all big V8s with heavy pistons and valvetrain. Did you expect this 1650cc motor to use the same size valvetrain as a 5000cc V8?
I posted those vids to show with a lightweight valvetrain(which this motorcycle engine could have) can rev to high RPM limits.
It all comes down to the ability to control the valves, and with light valves and good springs, there is no reason that a pushrod engine won't rev past 10K.