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OS Surpass 52 Four Stroke OVERHAUL
Here are the upper cylinder components, and we're quickly approaching final assembly! The head assembly has been preped by cleaning and lapping the valves to insure a good compression seal. If you suspect your valves are not sealing you can test them by putting a few drops of alcohol in the manifolds then observe the combustion chamber for alcohol leaking through. If they are leaking re-lap the valves using toothpaste or lapping compound. It's very important that the valves seal perfectly. It's time to lubricate and insert your tappets (lifters) into the crankcase. Make sure the flat side goes in towards the camshaft. The tappets should easily slip into place, if not... you will have to polish the sides of the tappets. They must move up & down freely. Your pushrod guide tubes should have a small o-ring at each end as shown in the photo.Insert these into the crankcase just above the tappets and seat the o-rings. Seat the aluminum head-gasket in the head and carefully set the head in place while holding your pushrod guide tubes steady and inserting them in the head.
This gets kind of goofy trying to hold everything in place so I will explain how I do this. I put a small amount of grease on the head gasket to keep it on the head and a little grease on the lower o-rings. This will hold just long enough to set the head. NOTE: You do not need to put the PUSHRODS in at this time! So don't bother... Here is another method I use which works great too. Hold the guide tubes with your thumb then install the head with the engine upside down.
When the head is firmly seated install ONE capscrew towards the guide tubes and gently snug it down. DO NOT tighten it!
Now inspect your head installation LOOKING FOR properly seated o-rings & guide tubes. Also check to be sure the head gasket is in place!
Once this is confirmed, you can install the remaining capscrews LOOSELY. Again, DO NOT TIGHTEN any of these capscrews! Now with all the capscrews in place you may CAREFULLY tighten them in a criss-cross pattern. I tighten these to 34 OZ.IN, torque if you don't have a torque wrench then "tightly" snug them down trying to keep the same amount of torque on all 5 capscrews. Do not get carried away with the muscle on the capscrews! OVER-TIGHTENING is much worse than under-tightening.
Insert your PUSHRODS in the guide tubes and set your rocker assembly in place making sure the pushrods are seated in the rocker arm cups. Tighten the rocker arm assembly down with one capscrew is illustrated. Install your prop hub and a propeller. Rotate the crankshaft several times to seat all the valvetrain components. Lubricate everything on the valvetrain. Adjust your valves as per the owner's manual. I perfer to set my valves at .004" on both, this is just my preference... Once the valves are adjusted install the valvecover.
Install the intake & carb loosely with the HIGHEND NEEDLE opposite the MUFFLER as seen here. Jiggle the assembly back & fourth to seat the o-rings & gasket then snug it down. NOTE: the carb can be installed opposite as shown if your plane requires it. Your engine is ready! OK, I have 14 flights on the 52 and here are the numbers it generated:
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