650RJ (Seca)

Upper Crankcase Disassembly

J. Crankcase Disassembly

1. Remove the upper crankcase bolts, starting the highest numbered bolt. Turn over the engine and remove the lower crankcase bolts,




TCI Identification

The following is a guide to determing if a used TCI is appropriate for a given machine:


Cleaning the Hitachi Carb

This series assumes you took the carbs apart, and are trying to figure out how to put them back together again. If you haven’t taken them apart yet, it’s a good idea to skim through this first anyway. Address any questions to: xj-owners@micapeak.com, and we’ll try to talk you through it.


Pictures and text by Dwayne Verhey


Cylinder and Piston -- Inspection and Repair

F. Cylinder

1.    Inspect the cylinder walls for scratches. If vertical scratches are evident, the cylinder wall should be rebored or the cylinder should be replaced.

2.   Measure cylinder wall wear as shown. If wear is excessive, compression pressure will decrease. Rebore the cylinder wall and replace the piston and piston rings. Cylinder wear should be measured at three depths with a cylinder bore gauge. (See illustration.)


Cylinder Head Removal


It is not necessary to remove the engine in order to remove the cylinder head, cylinder, or pistons.

A . Preparation for Removal

1 All dirt, mud, dust and foreign material should be thoroughly removed from the exterior of the engine before removal and disassembly. This will help prevent any harmful foreign material from getting into the engine oil.

Lower Crankcase Reassembly

2. Lower crankcase

a.   Install the shift cam and secure it with the guide pin. Install the stopper plate and bolt and tighten securely.

b.   Install the neutral switch.

c. Install the transmission drive axle assembly into the crankcase.

Cylinder and Cylinder Head Disassembly

13. Remove the front cylinder holding nut and remove the cylinder assembly. It may be necessary to tap the cylinder lightly to loosen it from the base gasket.

14. Remove the rear cam chain guide by loosening the holding bolt.

1. Holding bolt 2. Rear cam chain guide

Crankshaft, Con rods and Bearings -- Inspection and Repair

I. Crankshaft

1. Crankshaft run-out

the crankshaft at both ends on V-blocks. Measure the amount of
crankshaft run-out on the main bearing journals with a dial gauge while
rotating crankshaft.

Run-out limit: 0.040 mm (0.0016 in)

If run-out exceeds limit, replace crankshaft.

2. Inspection of bearings

Transmission -- Inspection and Repair

L. Transmission

1. Inspect each shift fork for signs of galling on gear contact surfaces. Check for bending. Make sure each fork slides freely on its guide bar.

2.    Roll the guide bar across a surface place. If the bar is bent, replace.

Middle Gear Adjustment

C. Middle Gear Servicing

1.    Disassembly

Refer to page 39 for disassembly.

2.    Inspection

Refer to page 52 for inspection.

3.    Gear lash check

The middle gear lash can be checked only when the gears are installed in the crankcase.