AM 25 REBUILD

This engine was a gift from my friend Ken Buckley saying"Merry Christmas"

GEE thanks mate, what can I do with this?

Well, the first step is to give it a bath in our chemical cleaning bath and go from there.......

So now we can see where to start. The first step is resizing the worn crank bush up from the original 3/8" to a nice new and true 10mm diameter. We also made a small adjustment to the venturi for better gas flow through the inlet port.

Now it's time to start on the new crankshaft.

Also the front end parts are now added..........

Next step is make the tooling needed to finish the big and and then machine in the porting and counterbalancing.

 Below is the finished crankshaft.......

Now we assemble the new crankshaft into the case and add the prop driver, prop washer and nut.

next is the back plate......

Now lets look at the piston, cylinder, head and con rod parts.

We have removed the rod from the piston and checked its condition.

The rod is ovulated at the big end and worn in the little end so we will be making a new rod. With the cylinder liner damaged with a broken mounting lip we will also be manufacturing a replacement liner along with a new piston, gudgeon and contra piston. Having to make a replacement liner will present us with the opportunity to redesign the less than ideal porting arrangement and use porting more like that of the Oliver Tiger.

Below photo shows the new con-rod and gudgeon pin. The new rod has lube holes drilled into both the big and little and to improve lubrication and therefore longevity of the new parts....

Now we assemble the rod onto the crank and final assemble the back plate.

Now it's onto the piston blank and the cylinder liner.

We have made the replacement cylinder head to accomodate a slightly redesigned cylinder liner to help us eek out substantially more power from this engine, hopefully.

Here's the new cylinder liner blank ready for porting.

Next is to machine in the ports.

 

Now the liner is finished it's time for some lapping and then we'll fit up a new piston and contra piston.

 

Now it's onto the piston.........

 

Now we make the liner base gasket and assemble the cylinder onto the rest of the engine......

Test assembled to make sure everyone plays nicely together.

 

Next up is the compression screw and needle valve assembly...............