YZ450F bottom/top end rebuild


13 replies to this topic
  • iFR

Posted October 03, 2015 - 11:10 AM

#1

Hi there.
My 07 YZ is asking for a engine rebuild, I recon. My engine is really noisy :(
But I'm wondering, what brand of engine parts, do you guys think is the best?
Oem material? Wiseco, athena, CW, Vertex?
Piston crankshaft etc.
appreciated!

  • knuckleduster271

Posted October 03, 2015 - 10:55 PM

#2

Hi there.
My 07 YZ is asking for a engine rebuild, I recon. My engine is really noisy :(
But I'm wondering, what brand of engine parts, do you guys think is the best?
Oem material? Wiseco, athena, CW, Vertex?
Piston crankshaft etc.
appreciated!


Depends on what your aiming for after the rebuild..
If you just want a reliable fresh motor go all oem.
If you have performance in mind I'd go with some aftermarket parts as well as Oem..
I'm in the process of doing a rebuild on my wr450, I chose to go performance on mine.
I bought an oem crank pin and bearing
Oem main/balancer/case half bearings.
A Carrillo connecting rod
Vertex hi compression piston
Hotcams valve springs
Oem gaskets.

  • iFR

Posted October 04, 2015 - 03:34 AM

#3

I only ride woods. No MX whatsoever.
And to be honest, this YZ makes more power that I can handle lol.
Perhaps I'll stick with oem material, and a performance piston. What's the best piston?

  • knuckleduster271

Posted October 04, 2015 - 07:27 AM

#4

I only ride woods. No MX whatsoever.
And to be honest, this YZ makes more power that I can handle lol.
Perhaps I'll stick with oem material, and a performance piston. What's the best piston?


If your want to stay with stock compression I think the Oem piston is as good or probably better than any aftermarket one.
I prefer the stock piston pin snap rings over most aftermarket piston pin clips.
I'd buy some new valve springs and valve stem seals while your at it.

  • iFR

Posted October 04, 2015 - 10:48 AM

#5

Thanks for the honest opinion.
I'll probably just buy only oem parts :)
I've been recon some prices ... This will cost me about 700€ :( damn
Bike still runs, and runs great, pulls freakin hard. Much harder than my friends 490cc Athena RMZ
But my engine is becoming really noisy, does a weird knocking... Time for a rebuild.

  • knuckleduster271

Posted October 04, 2015 - 12:31 PM

#6

Thanks for the honest opinion.
I'll probably just buy only oem parts :)
I've been recon some prices ... This will cost me about 700€ :( damn
Bike still runs, and runs great, pulls freakin hard. Much harder than my friends 490cc Athena RMZ
But my engine is becoming really noisy, does a weird knocking... Time for a rebuild.


Im in the process of a complete rebuild myself due to a noisy engine.
It sounded fine cold but once she warmed up a bit it started clattering.
The source of my noise was mainly the big end rod bearing but the two balance shaft bearings had some play as well.
I opted to replace them all while i was in there.

  • iFR

Posted October 08, 2015 - 06:24 AM

#7

http://youtu.be/OKohxR6dgV4

Does this noise means it's time for a rebuild?

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  • knuckleduster271

Posted October 08, 2015 - 06:47 AM

#8

Some will say its normal and that our bikes are noisy anyways- mine sounded exactly like that- it started gradually getting louder.
Is it quiet when you first start it cold?

  • iFR

Posted October 08, 2015 - 07:26 AM

#9

No, cold or hot, makes always the same noise!
It's making this noise since early 2014, so, about 1.5 years...

  • knuckleduster271

Posted October 08, 2015 - 11:10 AM

#10

What are your valve clearances like?
I cant tell in the video, is there an aluminum bash plate on your bike? They amplify engine noise x100.
A couple things that can help diagnose it- take out the oil filter and cut it open. Unravel the paper and look for bronze/brass colored glitter (or any glitter for that matter) you can also try adjusting your valves on the tight end of the clearance spectrum.
If neither of these works you can do an oil change with a heavier oil and see if it tones it down, if it does then you can be pretty certain its the rod bearing.

  • iFR

Posted October 08, 2015 - 11:29 AM

#11

Valves are in spec.
No, I don't have any bash plate on my bike.
I need to do a oil change soon, I will use heavier oil , thank you! ;)

I'll see the oil filter, good idea. If I find glitter, what does that mean?
Thanks on advance.

  • knuckleduster271

Posted October 08, 2015 - 02:56 PM

#12

Glitter is the sign your motor is eating a bearing. If there is no metal in the oil filter its probably that the bearing is badly worn but still intact.
Thicker oil will just close up some of the excess clearance of a worn bearing, its not a fix or good even for a temporary band aid, it basically just helps diagnosing noises like these sometimes.
How many hours do you have on it?

  • iFR

Posted October 08, 2015 - 03:28 PM

#13

Don't really know, I think this motor is untouched though...

  • grayracer513

Posted October 09, 2015 - 06:30 AM

#14

You will have metal in the drained oil and used filter. Will.  No doubt.  It's just a matter of what sort of metal there is and how much.  Almost all of it, under normal conditions, is from the transmission and the clutch. They're both messy assemblies that way.

 

By far most of it it should be in the form of pretty fine steel particles and aluminum slivers.  The stuff that points to failing bearings is small "square" pieces of steel in the form of flakes, somewhat like glitter. 







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