Royal Enfield diesel conversion with Ruggerini MD151

My first Enfield diesel build was with an Yanmar L100 engine, and it was finished by 90% when I found an 2 cylinder 654 cc 16 HP Ruggerini MD151 engine at a quite well known auction site.
It was in good condition, “just” the piston rings needed to be renewed :!:

Nowadays it is the same engine as Kohler/Lombardini 25LD330-2 and it is a 650 cc version of the 850 cc version Ruggerini MD191/Lombardini 25LD425-2.

Mechanical fuel pump, the tank and exhaust muffler are omitted 🙂

These engines have the same mountplate shape at the output shaft as the the original Enfield Taurus 6LD325 engine, so it fits nicely to the Taurus inner primary chain case.
That is, no need for an adapter plate between engine and inner primary chain case WHEN using the long Enfield gearbox diesel mainshaft version !

Primary chain, clutch/mainshaft support bearing and sketch of primary chain wheel

The big challenge is always to align the engine to clutch and to achieve adequate “round-the-engine” clearence.

The following pictures show my mounting fixtures between engine and gearbox, engine and downtube, enginehead and frame..

Square tube 38×40 mm 200 mm long fitted to engine. Later welded to the gearboxplate (5.6 mm thick).
The 6 hole engine plate 4 mm thick.
Fixture between gearbox and rear side of engine.
Made of 4mm and 5.6 mm steel plate and square tube, weight 2.5 kg
Frontadapter weight 1.9 kg
Engine head adapter. Connects to the Enfield frame with a rod, 25x115x5 mm piece of steel.
Made of 5 and 6 mm steel plate pieces, weight 0.4 kg.
The leftmost 2 holes are to fit the diesel filter
Engine in frame, ready to test run
First start in july 2013:
Getting out for a local ride 😉 :
I wanted a better clutch support bearing than the HP bush bearing due to the engines 32 Nm torque.

I tried the bush bearing in my Yanmar build, it went hot and the bronze bush crashed the alu bearing housing !

Here is the bearing housing sketch with an oil seal 20x32x7. For now I have added a HP oil seal on the outside of the chain case !.

The 4 holes need to be drilled for the Allen screws to fit the Taurus inner chain case bush bearing mounting threads.

A KN SU airfilter is replacing the industrial filter, using a piece a steel plate “interface” the inlet to the SU filter:

Slimlined the Ruggerini flywheel – got the weight down from 7.1 kg to approx. 5.1 kg.: