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Podcast

Episode 20: Top End Rebuilds Part 2

CBtopendEpisode 20: Top End Rebuilds Part 2

Episode 20 continues with Part 2 of our series on Top End Rebuilds. We pick up where we left off after describing disassembly of your motor to prepare for a top end rebuild. This episode covers the tools necessary to rebuild your top end and the steps to prepare your motor for final reassembly. It’s recommended you have listened to Episode 19 before starting this show.

Notes for this episode:

Assembly

Piston skirt scoring:
Debris between cylinder and piston
Motor ran hard before at operating temperature

Rebore
Will discuss next episode

Pistons
Thoroughly clean piston ring grooves, if using same pistons
Install new piston rings in appropriate orientation
While installing piston to connecting rod, be aware of piston orientation mark on top of piston
Slide wrist pin through piston and connecting rod and insert wrist pin clip

Deglazing/honing:
Adding a surface for the new rings to break in
Oil the cylinder wall thoroughly and tool
With triton hone or ball hone on drill move tool up and down through cylinder at a constant quick motion
Remove tool out of cylinder whilst still in motion

Removing old gaskets:
Gasket scraper
Razorblade
Scotchbrite pad on die grinder

Heads:
Remove all old gaskets and check for head warpage (use glass/mirror)
Thoroughly clean heads
Replace valve guide seals

Heads resurfacing
Start with 220 grit and move head in a circular motion for about 30 seconds and check work. Use a lot of WD-40
Check for high and low spot. Continue till surface is even
Finish with 320 grit
Too smooth and you won’t get proper gasket seat properly

Valve Lapping
Remove any carbon deposits off of valves
With valves removed, apply a light coat of valve grinding compound on valve seats
Insert valve and with a valve lapper rotate valve back and forth
Check valve for even surface and excess pitting
Lap valves until there is a solid matte grey ring on valve and valve seat
Thoroughly clean and remove all grinding compound from valve and seat

Install Barrels/Jugs/Cylinders
Replace gasket
By hand or with a piston ring compressor, slide pistons into cylinders
Gently seat barrels to the case
Oil cylinder walls

Heads Install
Install valves and valve springs
Install new gasket and place head on barrels
Insert head bolts/nuts and hand tighten
Torque down to manufacture spec and pattern

Camshaft install
Follow manual steps
Make sure cam and crank timing is correct
Install cam guides
Adjust valves
Slowly rotate crank to check for any binding and proper cam timing

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