Power comparison between 2 '99 YZ400's

4 replies to this topic
  • Pothole

Posted October 13, 2004 - 07:07 AM


My friend and I both have '99 YZ400's. Both bikes are in about the same condition. His bike is all stock except for a White brothers E-series pipe on it, just the end section, not the header. My bike is all stock except for a Promoto end cap (with the spark arrestor screen installed) and a WR flywheel and stator. When comparing the two bikes power characteristics, his bike is alot snappier off the bottom, and feels like it has more power. Could that WB pipe be giving him that power advantage? As a side note, that WR flywheel is about 10-12 ounces heavier than stock, although I didn't notice really any power loss after installation, just a smoother powerband.

  • Dano426

Posted October 13, 2004 - 08:46 AM


The E-seris will give you a little more pep and power than the stock exhaust, but I think what you are noticing is your flywheel. The whole point of a heavier flywheel is to add mass to your engine so it will take longer to rev - hence be less snappy and have less tire spin.

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

Posted October 13, 2004 - 10:55 AM


Ditto on flywheel

  • onekyoung

Posted October 13, 2004 - 12:14 PM


Definately the flywheel diff. Before and after FW installs are hard to notice a huge difference until you race a stock YZ, then the difference becomes painfully appearent :cry:

  • Fastest1

Posted October 13, 2004 - 03:57 PM


Not only does it take longer to accelerate, it takes longer to decelerate. Mass keeos the engine running in low speed situations.

Related Content


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

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

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies

2016 YZ450 by CaptainKnobby

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  59 replies

Wilson the Blue Privateer by jetfuel

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  50 replies

Michigan Motocross Tires by 288yz450

Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply

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.