splitting cases on 03 yz450f (How Hard)?

10 replies to this topic
  • dirtdevil72

Posted September 06, 2008 - 11:07 AM


Need to split cases due to a cracked case on 03 yz450f and was wondering what tools are needed, or any special tools that are needed? I have the new cases to put on any suggestions.

  • grayracer513

Posted September 06, 2008 - 03:22 PM


The only special tool you can't get along without very well, and shouldn't try to is a flywheel puller. Follow the manual, keep your eyes open, keep your parts organized, and you'll be OK.

  • shortburb

Posted September 06, 2008 - 08:35 PM


I did mine about 3 months ago. It was my first time. I had a friend whose done a few, help....it was less complicated than I thougth it was going to be.

  • lucio2

Posted December 03, 2008 - 10:00 PM


What parts were worn and needed replaced?? Right now my 05 YZ450F clunks when you put it in first gear. Did you replace the crank assy.?? Also,
did you notice a big difference once everything was reassembled??

  • crayztwentyseven

Posted December 03, 2008 - 11:23 PM


easy, just make sure to reseal wth silicone when you put it back together

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • 426 NOOB

Posted December 03, 2008 - 11:24 PM


Take your time and youll get it.

  • Smokeslider

Posted December 04, 2008 - 01:46 AM


Take crap loads of pictures as you go and keep everything in plastic bags with sharpie marking on the outside of what the parts are...

  • tnl

Posted December 04, 2008 - 06:28 PM


I wish I tried to do mine last year rather than having Insurance pay for it. I could of used the extra $ to mod the bike up.

  • tdamore

Posted December 04, 2008 - 09:55 PM


where are you at in CA? I just did mine and it was super easy.

  • yammamike83

Posted April 23, 2014 - 10:54 AM


Has anyone found a solution to all these 03s cracking the case behind the kickstart ? This is my first yz450f I love them I also have an 05 yfz450 quad iv never opened one of these engines up and if I can get away with fixing the case without doing so pls let me know how it's done . What have others done when this has happened?I've read about the lot of these having the same problem but haven't found a solution. This is the first forum I've joined and really like how u help eachother .

  • grayracer513

Posted April 23, 2014 - 11:25 AM


Why did you post your question in a thread concerned with a different topic instead of a new topic pertaining to your issue?


The problem with the '03 was the kick starter assembly, which has been upgraded in the parts system.  The replacements are all the newer upgraded pieces.  The cases need to be welded and machined, and the starter assembly replaced.

Related Content


YZ450F 03 Sparks driving me crazy by SirAttard

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 5 replies

Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Thinking about Yamaha 250... by Arctic Pride

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  491 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

100 hrs on 2014 yz450f, shim valves or replace them? by ttr230rider6

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  79 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.