04 YZ450f timing and valve clearance questions

42 replies to this topic
  • NorthernMNSurf

Posted June 14, 2016 - 08:50 AM


Thanks grayracer, that's the advice I was looking for. I will be replacing the crank, as well as the top end as soon as possible. It looks like I'll be spending around $850 altogether, which is not a bad trade for a learning experience and a fresh bike!

  • NorthernMNSurf

Posted June 14, 2016 - 01:39 PM


It looks like the bottom end kit (hot rods) doesn't include the applicable transmission bearings. (I only see the crank bearings, but will investigate later)

Q: how hard is it to replace the trans bearings? Is it sweat in installation? Anyone done it?

Edited by NorthernMNSurf, June 14, 2016 - 01:39 PM.

  • grayracer513

Posted June 14, 2016 - 01:46 PM


The only one difficult at all is the left side main shaft bearing.  The difficulty is due to the bearing being installed in a "blind hole", meaning it can't be driven out from the opposite side of that from which it's inserted.  For this, you can either use a blind bearing puller (slide hammer and inside puller), or heat the case to 230 degrees (Fahrenheit) and slap it down on a wood bench a couple of times to drop the bearing.

  • NorthernMNSurf

Posted June 28, 2016 - 09:24 AM


Thanks for that info gray, I will probably use a loan-a-tool blind bearing puller.
I am about to order everything I need from Rocky Mountain and Motorsport; any chance you could tell me if I'm being thorough enough? I'd like to replace everything, within reason, but I'll settle for peace of mind!

Hot rods bottom end kit
Tools: clutch/flywheel holding tool
Crankcase puller/installer
Crankcase splitter
Impact screwdriver

Cylinder works top end kit w/cylinder
Hot rods transmission bearing kit
Hot rods counter balancer bearing kit
(I already have a hot rods water pump shaft and rebuild kit, and the top end oem gaskets)

Anything I missed?

Thank you!

Edited by NorthernMNSurf, June 28, 2016 - 03:27 PM.

  • NorthernMNSurf

Posted July 21, 2016 - 01:39 PM


All that + an oem cam chain ordered today! Am I on the right track?

Edited by NorthernMNSurf, July 21, 2016 - 01:39 PM.

  • grayracer513

Posted July 23, 2016 - 09:44 AM


Looks like.  Whose piston is in the CW kit?

  • NorthernMNSurf

Posted July 23, 2016 - 10:02 AM


Vertex; do you think it would be wise to swap the rings in the kit for oem?

  • grayracer513

Posted July 23, 2016 - 10:09 AM


I would have recommended that if it were Wiseco, but Vertex is a good piece.  One or two compression rings? (Two or three rings total)

  • NorthernMNSurf

Posted July 25, 2016 - 06:37 AM


Two compression rings: I'm assuming that's better..

Edited by NorthernMNSurf, July 25, 2016 - 06:42 AM.

  • grayracer513

Posted July 25, 2016 - 12:19 PM


It's more durable, yes.  The single comp ring config is a low drag, race-only option that will require ring replacement somewhat sooner.

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  • NorthernMNSurf

Posted July 26, 2016 - 04:23 AM


Makes sense, thank you very much for the heads up. Work on the YZ will start soon!

Edited by NorthernMNSurf, July 26, 2016 - 04:24 AM.

  • NorthernMNSurf

Posted July 26, 2016 - 04:25 AM


ImageUploadedByThumper Talk1469535898.072789.jpg

  • NorthernMNSurf

Posted July 26, 2016 - 10:21 AM


I don't remember seeing the manual specify between yamabond 4,5,6B, or 7 for the casing gasket... Anyone have any knowledge on this? (If I see the answer in the manual when I get home, I will delete this post)

  • NorthernMNSurf

Posted July 27, 2016 - 05:56 AM


ImageUploadedByThumper Talk1469627807.567250.jpg

The closest answers I can find all include threebond in there somewhere, such as;

"Product should be used where Threebond 1215 is specified in service manual"

"Yamabond is repackaged Threebond"

Anyone have first hand experience?

Edited by NorthernMNSurf, July 28, 2016 - 05:17 AM.

  • NorthernMNSurf

Posted August 07, 2016 - 12:27 PM


Update: Called a couple of svc depts around and it looks like yamabond 4 is the closest equivalent.

  • NorthernMNSurf

Posted August 11, 2016 - 02:44 PM


ImageUploadedByThumper Talk1470955402.286038.jpg ImageUploadedByThumper Talk1470955421.438508.jpg ImageUploadedByThumper Talk1470955442.651636.jpg ImageUploadedByThumper Talk1470955467.466562.jpg

  • NorthernMNSurf

Posted August 11, 2016 - 08:13 PM


ImageUploadedByThumper Talk1470975186.635388.jpg ImageUploadedByThumper Talk1470975204.520321.jpg

  • NorthernMNSurf

Posted August 11, 2016 - 08:16 PM


HELP! Anyone have any ideas on what this may have been or where to start looking for broken/missing pieces?

ImageUploadedByThumper Talk1470975237.940957.jpg ImageUploadedByThumper Talk1470975250.390369.jpg ImageUploadedByThumper Talk1470975269.177301.jpg

Found these chunks in/around the strainer. ImageUploadedByThumper Talk1470975325.760649.jpg this pic with the penny is to show the thickness of the rounded chunk

  • grayracer513

Posted August 11, 2016 - 09:26 PM


The rounded chunk is a Woodruff key.  There's only one in a YZ450 (correct me...), and that goes on the crank to index the flywheel.  Apparently it was pushed out of its slot during assembly without being noticed and ended up in the bottom.  The piece of sheet metal next to it in this pic may be a locking tab that was reused, cracked and broke off, or it might be something else, but it went between the teeth of a couple of gears somewhere. 





I would guess bearing failure someplace.  The screen was sucked into the tube because it became clogged with debris, and the pump basically tore it out of the way.  The junk that caused the screen to fail went through the return oil pump and is in the oil reservoir in the frame.  The pump itself may be damaged or seriously worn, and so could the well in the crankcase where the pump turns. 


At some point, you're going to have to decide to fix it or cut your losses.

  • NorthernMNSurf

Posted August 12, 2016 - 01:41 AM


Can I flush the frame reservoir? Is there a way to check the pump and case for failure/wear on my own?

I know the point will come when I will have to decide, I'm just hoping with a whole new bottom and top end, I'll have a solid bike. Crankcase damage is another story though... If like to be thorough before it's too late to return the parts!

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