Putting my Saito back togethe....but I dont know for sure what the postitioning of the Piston should be when the cam gear is dropped back in. The cam gear has a marking that should be at 6 o'clock...but what about the piston? Should it be all the way up? PLEASE HELP


Also is there a safe way to check that it was done right? Any help would be great. This is my first rebuild.

Put the piston at Top Dead Center (TDC) The timing mark on the cam shaft points straight down and when it is orientated as such there is a small hole in the cam shaft that lines up with where one of the lifters installs that you can CAREFULLY hold the cam in place with an allen wrench, after you remove the lifter, while you install the cam housing to the engine block.

The hole lines up with the intake valve lifter hole

OK...Ive got the cam back on...no issue....but no i can get the cylinder head on while properly lining up the push rods. When i bolt everything together ...I dont get the same compression feel i got priro to taking engine apart. Whats the trick with getting the pushrods on correctly?

Saito 91

Experience?

The pushrods have to be aligned into the sockets in the rocker arms. I usually do this after I get a bolt into holding the cylinder in place.

The small end of the pushrods go towards the rocker arms.

If the tip of the pushrod is caught on the lip of the adjuster on the rocker arm there will be no compression.

If the engine is all together, the carburettor must be fully open in order to properly judge the compression feel.

To check your work, put the piston at top dead centre on the compression stroke. Now turn the crank 360 degrees or one full turn. As you move the crank back an forth it top dead centre both valves should be rocking back and forth. if only one is, you ain't got it

The two valves should be somewhat open the same amount but one will be closing and the other opening

That really does help. I will take a look at it to make sure ive got it. Thanks for the tip!

Yes, That's the valve overlap one hears about. Also if you have any motor with no timing marks or indiscernible marks, this method will time any 4 stroker.

I noticed that when i re-built my FA-72. The valves have a ton of over lap. I had an old chevy that had a pretty hot motor an when i built it i installed a cam that had alot of overlap. Now on a multi cylinder engine i can understand how it can give you an edge. But on a single cylinder saito you don't have other cylinders carring the one thats just pushed the exh out. Hey unless both valves being open makes it scavenge? I think thats when the hot gasses leaveing the cylinder sorta help pull a new charge of fuel an air in from the vacume created while the intake is open right before the exh valve closes

I really should think about these things before i start typeing, an then you guys would not have to see me answer my own question like a moron----

The model airplane engine needs some flywheel action of the propeller to carry it through to the next combustion sequence

Yeah i thought of that after i clicked ok. My FA-72 is on a model that won't let me go over 12 inchs on the prop. I ran a top flight 12x7 but the engine wanted to kick back when you idles down. Now i have a heavy APC 12x8 an it works great. It puts a load on the engine