ANATOMY of a SICK SAITO
PART TWO Page THREE: Re-assemble

Piston & rod orientation is CRITICAL because there's a slight off-set in the rod position on the piston. Look at the photo, and you'll see the difference in the length of the wristpin bosses. This off-set is intended to keep the rod from rubbing the backplate when you go up vertical with your airplane. If you install the piston backwards,   the piston & rod will bind in the cylinder. There's an orientation dot on the rod. Install the rod with this dot facing the short wristpin boss as illustrated. You will reference this dot when the piston is inserted in the cylinder.    

Thoroughly lubricate the piston ring,  and rod. Install the 2 teflon buttons (wristpin keepers) into the piston.

Now CAREFULLY insert the piston by compressing the ring and slipping the piston into the cylinder. Have the Reference dot(on the rod)  facing towards the INTAKE side of the cylinder as illustrated. THIS IS CRITICAL! You must install this RIGHT!   

Now CAREFULLY insert the rod (and cylinder) on the crankshaft with the Reference dot facing towards the REAR of the engine. THIS is CRITICAL!

Make sure your guide tubes and pushrods are in place before you seat the cylinder on the crankcase. Carefully seat the cylinder,  pushrod (and guides) on to the crankcase. Make sure everything is properly seated then bolt the cylinder down using 4 capscrews.

Lubricate all moving parts again.

It's time to "CONFIRM" your cam timing is CORRECT. This is simple to do, but it's the MOST CRITICAL part of re-assembling your engine! What you want to do FIRST is install your prop hub and install a prop. Now rotate your crankshaft watching your rod, and find TDC. You will be at EITHER at Top Dead Center on COMPRESSION or in between strokes. IE: between INTAKE AND EXHAUST strokes.  You want to be BETWEEN Intake & Exhaust strokes. NOTE: Your camshaft has valve "overlap" on the lobes whereby both valves are slightly OPEN at the same time. SEE: photo below...

This "overlap" is  PRECISELY located at Top Dead Center on your crankshaft.

Rock your crankshaft back & fourth at TDC and observe your rockers. both should be actively moving slightly. If so, your cam is timed properly. Your Saito engine will tollerate a slight mis-timing of PLUS or MINUS one tooth on the camshaft without adverse effects. If it's minus one tooth, you'll get a little more torque. If it's plus one tooth you'll see a little more RPM but you'll have to lower your prop pitch since you will loose some torque. It's BEST to have the cam timed properly!

Let's test what we've done so far:

Your timing is correct, and the crankshaft rotates smoothly while the valve train is working. You may or may not have good compression at this time, since we haven't adjusted the valves yet. You shouldn't feel any binding on the crankshaft and the bearings should be smooth. If so, then we are ready to continue...

Adjust the valves according to the owner's manual, and install your valve covers.

Now install your backplate & new gasket as illustrated in the photo, having your vent line(s) on the bottom. After you tighten the backplate down rotate the crankshaft to be sure the crankshaft & rod IS NOT rubbing the .backplate On very rare occasion the backplate may need 2 gaskets for proper clearance.

Install the aluminum ring on FIRST followed by the o-ring. Slip the carb & manifold on the cylinder and bolt it it down with the 2 capscrews.

Make absolutely SURE the o-ring is not damaged and properly seated as depicted in the photo!

The engine should be inspected one last time prior to firing up. Rotate the crankshaft several times and check for un-usual binding or hanging.The compression should good snap action. Check all the capscrews, check the o-ring seal, work the carb linkage. You may want to add a little more after-run oil to the crankcase prior to the first fire-up. 

CONGRADULATIONS! Your engine is ready. Please follow your Owner's Manual regarding correct prop size for break-in AND follow the recommended BREAK-IN Procedure.

About your fuel selection: Avoid fuels that contain CASTOR. Four Strokes stay much cleaner with fuels that contain 100% synthetic. For maximum power you can go as high as 30% nitro with Saito engines. However, 15% nitro works great. There's no need to by "Four Stroke" type fuel. It has less oil and totally un-necessary. Just use 2 stroke glow fuel.

Old glow fuel is your engine's worst enemy. Do not fire up your new overhauled engine on that old fuel that's been sitting around! Glow fuel degrades with age and worst of all is absorbs moisture!