mblue2050

My Feedback: (6)

Rebuilding a Saito .72. Overheated?

Anyhow. New conecting rod, valve springs and piston ring. The rod egged where it rides on the crank. A nice place for a bushing in my opinion.

While inspecting the entire engine I had removed the cam gear assembly. I see crank to TDC and cam gear timing mark lined up per the manual.

My question is how do I insure I hit the correct spline. Held the crank TDC but the gear might have rotated when I assembled it.

Any suggestions to this first time tiny engine rebuilder would be appreciated

Woody218

My Feedback: (24)

Remove the rocker arm covers. With the glowplug out, rotate the crankshaft until you see the exhaust valve closing, and the intake valve opening. Insert a toothpick or such into the glow plug hole, move the crankshaft until you are sure it's at top dead center. This should be the area of maximum valve overlap, where both valves are open, and they should both be open an equal amount. Sight across the rocker arms, they should essentially be parallel with one another.

mblue2050

My Feedback: (6)

Thanks for the tip.
I will double check using you method.
I do think it is right and worst case scenario is a slightly out of time engine as nothing binds. Intake seems correct. Compession is good and exaust begins to happen as I think it should.
Long duration on these small engines apparantly.
I know what RPM's it turned with differnt props while running correctly so....
Guess I will just have to start it and see. Like I said nothing binds!!! Still much caution as this engine as suprised me a few times running perfect....backwards. Thats a bit supising on take off.
Seems there should be some easy way of insuring the cam gear landing on the correct spline on the crank. Bigger engines with overhead cams have an alignment tool.
As I said thanks for the help and anybody else who might have some help.

donkey doctor

Hello; I haven't had the 72 apart yet, but I have had most of the others apart and they all have a hole in the intake cam that lines up with the lifter when the timing mark isdown. What I do is remove the lifter and push a pushrod into the hole and hold it in position while holding the crank at tdc through the back cover opening. Then mount the cam chest on the engine with the pushrod in the indexing hole. After tightening things down, remove the pushrod and install the lifter, then continue with the assembly secure in the knowledge that everything is timed properly. It is easier to do then to tell about.