Measuring and/or Machining Crankcase

MEASURING AND/OR MACHINING CRANKCASE

General

The main bearing bores should always be measured each time the engine is overhauled and the crankcase is disassembled.

Measuring

1. Mount crankcase on engine holder P 201 in conjunction with mounting parts P 201 b and bolt both case sections.
Screw in all anchorage bolts and four M 8 nuts on bearing 1 (flywheel end) and bearing 8 (pulley end) finger tight.




2. Align both case sections with each other with light knocks from a plastic hammer. Joint must not offset in bearing bore no.8.

Measure bearing bore no.8 crosswise with an internal calipers, centering bore again if necessary.

3. Tighten all anchorage bolts and four M 8 nuts with specified tightening torque.

Anchorage bolts M 10 = 35 Nm
4 nuts (bearing 1) M 8 = 22 to 24 Nm (bearing 8)

4. Measure all 8 main bearing bores with an internal calipers.


If bearing bores are too tight, ream to standard size of 65.00 mm diameter with a standard size reamer.


The size for bearing bores 1 through 8 is 65.00 to 65.019 mm.



5. If bearing bores are too large, ream to oversize diameter of 65.25 mm (B bearing) with a rough reamer and finish reamer.

The control size for B bearings is 65.25 to 65.269 mm diameter.



Machining and Reaming

General

Bores in light alloy silumin crankcases must be reamed to B bearing size in two steps. Lubricating the reamer with gasoline is essential while reaming out bores.

1st step = rough reamer = 65.20 mm dia.
2nd step = finish reamer = 65.25 mm dia.


Reaming




1. Mount locally made tool on crankcase and clamp in a vise.




Locally Made Tool Sketch
Material: sheet steel or aluminum

2. Insert end bearing sleeve EL - 35 in bearing bore no.1




3. Insert end bearing sleeve EL - 35 in bearing bore no.8 and align with guide rod 35 x 1500.







4. Only now install the guiding fixture to support front of guide rod. Use M 10 x 45 bolts.




5. Run guide rod 35 x 1500 mm with reamer into bearing bore no.8 and ream out all bearing bores slowly and uniformly.

Note: Have a second person provide thorough lubrication with methylated spirits while reaming out bearing bores.