Yamaha YZ125 1994 - 2001 | Complete Engine Build Step by Step
#2stroke #yz125 #yamaha

Hey guys, Merry Christmas! This is the 1998 YZ125 engine I got in bins (literally.) I decided to restore it and turn it into a mild 144 big bore and it became the heart of the Grape Ape build! What bike should I build next?

CHAPTERS

0:00 – Intro

CENTER CASES

2:08 – Crank Installation
5:00 – Transmission Installation
5:45 – Shift Forks and Shift Drum
7:09 – Assembling Case Halves

STATOR SIDE

12:29 – Stator Installation/ Timing Adjustment
13:24 – Flywheel Installation
14:50 – Stator Cover Installation
15:40 – Sprocket Assembly Installation
16:35 – Case Saver Installation

CLUTCH SIDE

16:55 – External Shift Mechanism Assembly
19:16 – Shift Shaft Installation
19:50 – Kickstarter Assembly
21:32 – Kickstarter Shaft Installation
22:35 – Idler Gear Installation
23:45 – Primary Drive Gear Installation
24:53 – Clutch Assembly Installation
26:35 – Tightening Primary Drive Gear
27:07 – Clutch Pack Installation
28:48 – Pressure Plate and Springs
29:52 – Exhaust Governor and Actuation Arm
30:50 – Water Pump Gear Installation
31:15 – Right Crankcase Cover Installation
32:06 – Clutch Cover Installation
33:37 – Water Pump Impeller
33:56 – Water Pump Cover Installation

TOP END

34:19 – Ring Installation
35:27 – Piston Installation
37:04 – Athena Cylinder Explained
39:13 – Power Valve Installation
42:59 – Athena Base Gaskets Explained
43:49 – Cylinder Installation
45:30 – Power Valve Arm Assembly
46:00 – Power Valve Covers Installation
47:25 – Cylinder Head Installation
48:45 – Reed Installation

SHOWCASE/CLOSING

49:10 – Showcasing the Engine
49:54 – Running/Revving the Engine
51:13 - Closing

PARTS AND TOOLS IN THIS VIDEO - (These links may be affiliate links that I get a kick back for; there is no added cost to you)

Service Manual - https://bit.ly/3JgcY7y
Maxima Assembly Lube - https://bit.ly/3mySX2x
Yamaha Assembly Lube - https://bit.ly/3syeagW
Crank Installer - https://bit.ly/3qmaYSz
Anti-Seize – https://amzn.to/3qi8PJj
Stainless Bolt Kit - https://ebay.us/spKmlI
T-Handle Allen Set – https://bit.ly/3HbMeU4
Dead Blow – https://amzn.to/33LGcee
Topar Stator Cover (05-21) - https://ebay.us/25MiNE
Stator Cover Alternative (Boyesen) - https://ebay.us/gpYxeL
Moose Case Saver – https://ebay.us/2eeRpr
Aftermarket Kick Shaft – https://bit.ly/3Esm5yz
Clutch Kit – https://bit.ly/2YsRWjz
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Red Loctite - https://bit.ly/3FrCMLD
Loctite 272 – https://ebay.us/dCh44V
Benol - https://bit.ly/3JgJExT
Tusk Air Filter - https://bit.ly/3o60B4r
VForce3 Reeds – https://bit.ly/31BODHX
144 Big Bore Kit - https://bit.ly/3khyjml
M12 Impact Driver – https://amzn.to/308yXvz
Torque Wrench - https://bit.ly/3qhCORC

COMPANIES I TRUST

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Rocket Ron - https://rocketronracing.com
BPRacing - https://bpracingatv.com
Obor Tires - https://shop.obor-tires.com/

MERCH - https://michael-sabo.creator-spring.com/

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