Gents,

Excuse a little scolding, please?

Our engines are miracles of modern technology... at least the pieces turned out by hi-tech processes are. Assembly, particularly in low hourly wage parts of the world, may not be everything we wish it were. That leaves some of the responsibility up to us...

Even if you buy a new car, these days, a read of the owner's manual will suggest a "break-in" process for a certain period of time. It is, today, much less involved and crucial than it once was, but you'll gain by following the recommended precautions.

So, I recommend checking that the engine is bolted together well enough to run. I've been surprised (- shocked, SHOCKED, Rick -) to read that some of us don't bother!

Further, I recommend pulling the backplate - at least - off a 2-cycle to check whether there's any loose bits from the manufacturing and assembly processes floating around in the crankcase. If there are, a flush with rubbing alcohol should remove them. Oil the moving parts, and re-install the backplate.

"Torquing" the head is less critical now than it had been, but is still pretty important. Try backing off all the head bolts until they are loose, then running them in until they "just touch". Then back each out a half turn.

I.e., for a six bolt head, use a Star of David type pattern. Select one of the front bolts and call it 12 o'clock. Turn it in 1/4 turn, then go to the bolt at 4 o'clock and do the same, Then to the 8 o'clock bolt - same. Now, cross the head to the opposite - 2 o'clock - bolt and give it a quarter turn. Then 6 o'clock... Then 10 o'clock... Then diametrically across to the 4 o'clock for another 1/8 turn.

And, with this sequence, continue with ever decreasing increments, to draw the head down. In two or three more passes, you should feel definite resistance at each bolt. Continue to pull-in even increments, with a small handle diameter screwdriver, or the short tang of an Allen hex key, until you can't add any further draw-in. The head should be on square, evenly tight, and well-sealed for running, now.

(For four bolt heads, try to keep crossing the diameter as well as possible, say a sequence of 2 o'clock, 8 o'clock, 4 o'clock, 10 o'clock, then from 10 o'clock to 4 o'clock and round and round we go...)

A helpful thing to check is how free the shaft turns (before the 'pinch' zone in AAC/ABC or ABN engines). After each increment in tightening the head, roll the shaft back and forth to assure that you haven't pulled in any distortions. Again, this is less likely with more recent engines, but it can happen. Checking as I recommend at least gives confidence that we haven't bound up the engine by ham-handedness...

After the first few runs, test stand on in a model, go around the head bolts and backplate bolts, as above, to correct for any gasket 'settling' or compression from running loads, etc. This should last a long time...

Finally, every engine I've had in my hands came with some form of mfr's recommended break-in procedure. Try it: you'll probably appreciate it when your engine outlasts those of others who expected their toy to be ready to play with in the box, and performs better while lasting longer.

I first opened up a model engine back in the early-1950's, and have always found something that could be improved...