⭕ For the 1931 season,there was a complete new engine with a smaller crank case and smaller crankshaft.Now with single port cylinder head and downdraft intake.Many details have been changed from the old engines. For 1932,there were still additional small cooling fins on the housing and a lubrication groove in the cylinder base with some oblique holes to the piston.During the year 1933 all engines were again developed, first with 250 and 350 cc,later then 500 and 1000 cc.From the racing engines of the period 1931-33 only a few individual pieces were built.
The engine offered here is the final development of the famous dog-ear racing engines.A super rare motor with about 36 hp at 6000 rev/min!
The engine is completely dismantled and all original.All the parts in the pictures are genuine JAP racing parts-guaranteed no replica!
The case is very good and has no damage.The oil breathing is very special for this year.
The cylinder has a special lubrication (see oil terminal and copper tube) for an oil ring channel and several holes for piston lubrication.The condition is very good-no damage.With a matching JAP racing piston.
The cylinder head is designed specifically for this model and year.The inlet has 32 ??mm with 20 degrees downdraft.The 14 mm spark plug sits almost centrally.Single port.At the front a cooling fin and 2 small pieces are broken from other fins.Otherwise,the head is very good.
From the rocker box I only have the cover.The rocker arms are there includes all bearings,small parts,etc. The dog-ear covers are complete.
Original Crankshaft with flywheels in very good condition.A crank pin is currently not available.I believe it is the same size as the post war dirt track engines have.
With 3 roller cam followers.They (according to the year of manufacture) have bronze bushings.
The camshaft timing is extreme.With a valve lift of 9 mm instead of 8 mm as usual the racing engines have.
Original brass plaque for the oil-Castrol R (it was only for racing engines)
The magneto platform base is good and fine,no cracks,no welding.A cover I have unfortunately not.
The valves and triple valve springs are original JAP racing parts--new old stock!