YZ 450F do they need the oil upgrad like the yfz 450?

1 reply to this topic
  • aclemac

Posted March 18, 2008 - 03:31 PM


I just got a 03 yz 450f that I am rebuilding with a 478 big bore kit. I have seen many many threads about the yfz 450 needing a oil upgrade because the piston pin doesn't get enough oil. do the yz 450f motors have this same problem? if not, what's different?

Also, anyone know the jetting changes needed to go from stock to the 478 kit?


Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • grayracer513

Posted March 18, 2008 - 03:45 PM


This has just sprung up here recently all of a sudden, but you would think it would have been mentioned long before this if it were truly a problem. Of all the broken wrist pins I've only this week heard about, none were OEM Yamaha. I find that somewhat interesting, as is the fact that the info regarding there being a weakness in the oiling system appears to be coming from the manufacturers of aftermarket pistons.

Nevertheless, Yamaha has, if I recall correctly, increased the amount of oil sprayed on the piston, but that was to increase piston cooling, not address an oiling problem. Again I will say, this is the first I've heard of it.

Related Content


Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  57 replies

YZ450F 03 Sparks driving me crazy by SirAttard

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

Need help by Goforaride

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  68 replies

yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 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.