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grayracer513

Common Threads: Look here 1st! Mods, Maintenance, Common Issues and FAQ's

2 posts in this topic

Important: These threads are for reference and quicker access to commonly discussed issues only. They DO NOT replace the service manual or common sense, and not every contribution is necessarily 100% accurate! Whenever you consider doing one of the modifications here, I strongly suggest you read and evaluate all of the available info and consider carefully the up and downside, what it is intended to accomplish, the reversibility in case you don't like it, whether it is applicable to your bike, and any possible consequences. All of them have been successfully used by somebody, but I cannot vouch for each and every one. Thumper Talk itself endorses none of this information.

Note: Many of these threads are such that they need to stay on topic to be useful. Please be sure that any post you put up in one of these threads bears as closely as possible on the topic of the thread. For example, don't post questions about another members jetting in the jetting database. Post the jetting you use, and ask your questions in a new thread, or by PM. In a thread that focuses on one particular bike, try not to ask questions about a different model. Off topic posts are always subject to being weeded out.

Thanks,

Submit threads for addition to this list here -http://www.thumperta...ad.php?t=444209
Report errors or broken links to me by PM, please.

Part One: Engine, Transmission, and Fuel System

Engine

The Decompression Cam Mod (DCM) (for 400/426's Only) (This info does not apply to YZ/WR250F models)

Link to Instructions:
http://www.thumperta...078#post3706078

Clarification of "DCM" Timing Instructions
http://www.thumperta...040#post5378040

The whole, original 450 DCM Thread:
http://www.thumperta...ead.php?t=60381

Oil Change Procedure:

Valve Clearance Check/Adjustment
http://motoman393.th...ech/valves.html

Oil Leak at Right Front of Engine, or
Right Radiator Appears to Leak (Smoke from Radiator and Exhaust ), or
Unexplained Open Hole in Front of Head.
http://www.thumperta...419#post1522419

Cam Chain Replacement
http://www.thumperta...405#post3150405

Timing Cams: How Many Pins Between Cams?
http://www.thumperta...845#post7467845

Lapping Valves? Cutting Seats?
http://www.wiseco.co...alveInstall.pdf

Breather Tube Re-route:
Discussion
http://www.thumperta...651#post4054651
A Clean, Simple Solution
http://www.thumperta...ad.php?t=706602
A Different Breather kit parts list
http://www.thumperta...573#post4956573

The Fabulous Glowing Red Header
http://www.thumperta...ad.php?t=236304

Engine makes noise
http://www.thumperta...131#post5345131

Dry Sump Oiling Systems
http://www.thumperta...903#post5221903

Paper vs. Mesh Oil Filters
http://www.thumperta...297#post4676297

Lower Oil Filter Cover Bolt Stripped
http://www.thumperta...ad.php?t=575367

Prevent Thread Damage to the Lower Filter Cover Bolt
http://www.thumperta...ad.php?t=634724

Engine sometimes very hard to turn over, no Auto Decompression, or feels locked up after stalling:
http://www.thumperta...763#post9110763

How Auto Decompression Works in a YZF:
http://www.thumperta...171#post6849171

Honing Nikasil Plated Cylinders
http://www.thumperta...759#post4380759

Water Pump Seal and Shaft Replacement
http://www.thumperta...ad.php?t=940018

Repeat failures of water pump seals, especially in '06 and later models:
http://www.thumperta...ad.php?t=785425

Cylinder Head Torque: What's with the Angles?
http://www.thumperta...ad.php?t=972816

Transmission

Noise at Idle; Stops When Clutch is Pulled
http://www.thumperta...282#post5362282

'06 YZ450F: Hard Shifting, Inaccurate Shifting, Jumps Out of Gear
http://www.thumperta...391#post4922391

The '01 Clutch Mod for the 2000 YZ426
http://www.thumperta...ad.php?t=461631

'07-'09 (possibly later models) Clutch gains free play when hot, slips
(Conversion to '06 clutch)
http://www.thumperta...940#post7261940

WR450 5 speed swap for 4 speed YZ450's
http://www.thumperta...046#post2761046

Wide Ratio Transmission for the '06 -'09 YZ450F
http://www.thumperta...ad.php?t=464212

Hybrid (or full WR) Wide Ratio Trans for 2010-2013 YZ450F
http://www.thumpertalk.com/topic/954114-wr-4th-5th-on-a-10-yz450f/

Fuel System

Electronic Fuel Injection

Yamaha EFI Tuner Manual:
http://www.mcnews.co...uner_Manual.pdf

2010 YZ450 Fuel and Timing Maps Used by TT Members
http://www.thumperta...ad.php?t=860507

 

How to clean the fuel filter on EFI YZ450's

http://www.thumpertalk.com/topic/1017998-2010-yz450-bogs-after-15-minutes/#entry10702600

Carburetors

FAQ: Where is the Idle Mixture Screw?
http://www.thumperta...ad.php?t=696672:

How to confirm your pilot circuit setting-
http://www.thumperta...ad.php?t=327405

Jetting Used by other Members: (Add only the info about the jetting you use. If you have a question or a comment, please post to a new thread)
http://www.thumperta...ad.php?t=694921

Cleaning Carb Jets and Passageways:
http://www.thumperta...726#post8021726

A Simple Guide to Jetting by the Seat of your Pants:
http://www.thumperta...699#post2881699

Changing Late YZ450 Pilot Jets Without Moving the Carb
http://www.thumperta...ad.php?t=556427

Exhaust Backfire on Deceleration
http://www.thumperta...599#post3710599
http://www.thumperta...613#post3350613

Every Thing (just the title,its not really everything) You Need To Know About Carbs-
http://www.thumperta...ad.php?t=404426

Info on the Zip-Ty Carb Mod
http://www.thumperta...ad.php?t=458476

The O-Ring Mod How-To
http://www.thumperta...233#post6157233

What a Leak Jet Really Does
http://www.thumperta...330#post4415330
http://www.thumperta...966#post6081966
http://www.thumperta...344#post6091344

Alternate Accelerator Pump Diaphragms and Leak Jet Info
http://m.bobbitt.hom...fm/tech/ap1.jpg
http://m.bobbitt.hom...fm/tech/ap2.jpg
http://m.bobbitt.hom...fm/tech/ap3.jpg

1/4 Turn Throttle Mod
http://www.thumperta...ad.php?t=485653

The BK Mod (accelerator pump mod for YZ426)
http://motoman393.th.../tech/carb.html

The "Taffy Mod" for YZ400 models
http://docta-zaius.f.../whats_new.html (Watch for pop-ups)
 
Replacing YZ400 carbs with newer units
http://www.thumpertalk.com/topic/1043225-need-help-with-99-400f-carb/#entry11011329

High Octane Fuels
http://www.thumperta...893#post2827893
http://www.thumperta...255#post2920255

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Part Two: Chassis, Electrical, and Miscellaneous

Chassis

How to repack swing arm/linkage bearings

http://www.thumperfaq.com/swingarm.htm

Greasing steering stem bearings how-to

http://motocross.tra...-steering-stem/

Updated '06-'08 Upper Steering Head Bearing to Prevent Water Contamination

http://www.thumperta...710#post6702710

How to Stop Chain Sliders from Wearing the Swing Arm:

Grayracer513's Method:http://www.thumpertalk.com/topic/946340-picture-of-chain-slider-wear-to-swing-arm/

Motoman393's Method:http://motoman393.th...h/swingarm.html

Chain Seems Too Loose When Adjusted to Specified Tension:

http://www.thumperta...182#post8906182

Chain Hits Frame, Rear Wheel Alignment:

http://www.thumperta...955#post4244955

http://www.thumperta...ad.php?t=548940

Basic suspension tuning tips-

Set your Race Sag

Use Sag to Check the Spring Rate

Basic Suspension Setup Guide

How to Bleed Twin Chamber KYB Fork Cartridges ('05 and later YZ/YZF)

http://www.thumperta...814#post8762814

Base Bolt/Jam Nut Clearance: Gap or No Gap? Clarification to the Service Manual Regarding Fork Damper Rod Jam Nuts ('05 and later YZ/YZF)

http://www.thumperta...008#post8002008

Fork Damper Cartridge Free Piston Mod to prevent Failure of the Piston and Improve Plushness

Mod:

http://www.smartperf.../YZMODASSEM.htm

Piston Failure:

http://www.thumperta...ad.php?t=650136

Wheel Interchange Information for YZF models

http://www.thumperta...ad.php?t=632582

'08 Front Brake Locks Up After Lever Replacement

http://www.thumperta...853#post5844853

Tire Change How-to (video link)

http://motocross.tra...ip-tire-change/

Lacing and Truing Spoked Wheels

http://www.thumperta...ad.php?t=583471

Electrical

Late YZ450 Street Grade Lighting System How-To

http://www.thumperta...ad.php?t=622555

Late YZ450 Baja Grade Lighting How to: (It's expensive!)

http://www.thumperta...ad.php?t=696590

Using a WR426 stator on a YZ426 (aka "Pink Wire Mod" or "floating the ground")

http://www.thumperta...52#post10674552

Misc

Owners Manuals

http://www.yamaha-mo...uals/index.aspx Printable

http://www.yamahaown...ook.com.au/?r=0 Mostly non-printable

YZF or WR450? How to decide?

http://www.thumperta...235#post8107235

450 Plastics Conversion on a 426

http://www.thumperta...ad.php?t=151436

DIY Carbon Fiber Parts How-To:

http://www.webbikewo...torcycle-parts/

How to Start a YZ426 (Video with Doug Dubach- Special Thanks to Yamaha Motors, and all the Good People at Dubach Racing Development)

(Requires QuickTime, or a player that will handle QT videos)

Part 1: (Cold Start) http://www.yamaha-mo...troke_vid_a.mpg

Part 2: (Hot Start) http://www.yamaha-mo...troke_vid_b.mpg

Note: Video may take a few minutes to download.

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