I'm sure that Clarence has wonderful credentials but when it comes to the VT21 he appears to not know his arse from his elbow.

My VT21 idles like a Swiss watch at just under 2,000 RPMs once it's warm on 10% fuel with 20% oil (half castor, half synthetic).

Connecting the crankcase vent to the fuel-tank is a big no-no and will stuff up the engine's lubrication system by not allowing sufficient oil blow-by between the piston and liner.

Likewise, connecting the nipple on the muffler to the fuel tank will also risk *major* engine damage because this is where the top-end (rotary valve and gears) gets its lube from.

Unlike a regular 4-stroke, you can't just rely on residual oil from a quick squirt with the oil can to keep a VT21's top-end lubed. The rotary valve is subjected to combustion temperatures and spins in the head. If the oil film decays or breaks down then the engine will suffer significant damage!

Likewise his use of 10% synthetic oil was a big no-no. These engines must have 20% oil with a good percentage of that being castor -- it says so in the manual and a quick inspection of how they work would show that the rotary valve assembly needs lots of *good* oil that will hold up at high temperature.

It sounds like Clarence was unfamiliar with these engines and got a bit out of his depth when reviewing them.

Mine is now 25 years old and still runs like a well maintained sewing machine. I replaced the bearings a while back but apart from that it's needed no work and is still running on the *original* glowplug!