I have a venture 50 with a OS 50 HYPER.I put the fan on the engine with red locktight ,got it real tight .When i tryed to start the thing the fan spins on the shaft .is there a part i"m missing or a secret to getting this thing tight? The engine has a shoulder thats 9.5mm fan hole is 6.3mm Is this enough bearing surface to ever stay tight?

First ditch the red locktite and use blue.

Second, clean all the surfaces with alcohol or brakecleen brake dust cleaner.

Third, use a crank lock tool to lock the crankshaft. Put some blue locktite on the fan and tighten it down, then put the prop nut on, again with blue locktite and tighten.

Let it sit for 24 hours.