FROG 250 Restoration progress

This is the engine as we received it, not looking to happy I must say.


The first stage of this restoration was to do an initial clean in a thinners bath and then attempt to dismantle the seized solid engine. this was achieved using gentle heating and lots of oil.

Once the engine had been dismantled, thankfully with out incurring any further repair work, the individual parts were re-cleaned in a fresh thinners bath, results below

Next step is to re-lap and polish the liner so I can replace the compression.

Here's the liner cleaned,re-lapped and ready for the new piston and contra to be fitted.

Now its onto making the new piston and contra, along with a new gudgeon pin and con-rod.


Next step is to now assemble the crank assembly to the case.We've also cleaned and repaired the original N.V.A. and made a steel prop washer.

Now it's onto the new con-rod and gudgeon pin........


Next it's fit the con-rod and piston assembly to the rest of the engine........

Now we check and adjust the piston to liner fit for the final perfect fit and reassemble the cylinder to the engine.........

Now we'll have a quick rummage through our parts bins to locate another tank and we'll make the needle bracket,then it's off to the test stand for a test run.


Now lets add some fuel.