Measuring Crankshaft Assembly

Note! As the illustrations in this service information are used for different model years and/or models, some variation may occur. However, the essential information in the illustrations is always correct.

Measuring the crankshaft
Use a micrometer.





Measure bearing journal out-of-round and taper. Measure at a number of points laterally and longitudinally.





For the correct values for connecting rod bearing and main bearing journals see Specifications.

Check crankshaft out-of-true





Use a dial indicator and magnetic holder.
Position the crankshaft with the two outer main bearings in the V block.
Turn the crankshaft and measure radial runout on other main bearing journals.
For the correct values, see Specifications.

Removing the piston rings
Use piston ring pliers.





Remove coke deposits. Scrape piston ring grooves clean with a groove cleaner or a broken and filed piston ring.
Check for damage, wear and cracks.

Checking piston ring axial clearance





Use new piston rings.
For the correct values, see Specifications.

Checking piston diameter





Use a micrometer and vernier caliper.
For the correct values, see Specifications.

Calculating piston running clearance





For the correct values, see Specifications.

Disassembling connecting rods/pistons
Check first that the piston and connecting rod are marked.





Piston marking: Scrape the piston pin clean. If the markings are unclear mark the piston with the cylinder number and an arrow pointing to the front of the engine.
Use a marker pen.
Connecting rod marking: Refer to Reassembling Engine, Assembling The Crank Mechanism.
Carefully push out the lock-ring using a groove-cut chisel.
Press out the piston pin with your thumb. Clean and check connecting rods, caps and screws for damage, signs of wear or cracks.

Check the piston pin alignment with the pistons





The piston pin must not be loose. It should be possible to push it through the hole using thumb pressure.
If the play is too great replace the piston.

Check the piston pin alignment with the connecting rods





The piston pin should slide through the hole with light thumb pressure.
If the play is too great measure the piston pin.
Use a micrometer.
For the correct piston pin diameter see Specifications.

Checking the bearing recess in the connecting rod big end





Visually check the bearing shells.
If in doubt measure out-of-round.
Use a bore gauge.
For the correct bearing recess see Specifications.

Checking the connecting rod in a connecting rod aligner
Check for out-of-true and twisting.

Caution: Check that the aligner fork is unbarred and round at the handle. Remove and apply the expander at the big end between each alignment operation.