Free mods done, and Muffler added... any more power to be had?

2006 WR450f, all the free mods done, aftermarket muffler added.  It's lightyears better than it was, but is there any way to get more snap and  power out of it.  I've never ridden a YZ450, so I don't know how tame or extreme it is, but I want it to perform more like the KX450f I am used to riding.  The WR is still just a little too tame for my tastes.

The KX450F is a lean mean motocross machine, while the WR is not, and wasn't built to be. You probably already realize that.

You're up on weight and down on power right out of the box. The options you have are: port and polish the head or order up one of those fancy GYTR heads; cams - '06 YZ450 exhaust cam is a popular choice, as is the Hot Cams brand; and an aftermarket CDI like Vortex. That stuff will get you in the neighborhood of 450 mx bike horsepower.

Then you can start removing the heavier extraneous stuff, like starter, battery, lights, and kickstand to start getting the weight down. Search "25 lb weight loss" on here for ideas and a list of things to remove to lose more weight. Then you'll be closer to your goal. If you do all the engine work yourself, you're probably looking at a little over $1000 in parts/machine work (unless you go big with the GYTR head).

I have tried every possible combination on the of the earth (I believe) to get the maximum power out of the older WR's without going stupid expensive or un-reliable.


Hot Cams YZ camset gives you about 6 more hp, most of it above 5k rpm, with the same throttle response as stock.

Adding a stage 3 port and polish to the head (done correctly) brings makes the power wider at both ends, and very 'snarly' when needed. 

Upgrading the Accelerator pump system to 2008  CRF450R specs (crfsonly kit) or using an R&D powerbowl-2 kit vastly improves the apump quality.

It is very fun....Much fun.  


 What I have now works quite well with more power every where, and still as docile as a lamb if you want it to be.


The WR motor has more reciprocating internal motor mass than all of the other similar bikes, so it will always rev slower, just so you know.


Also, MX bikes have a much more aggressive throttle cam/tube, so the WR will always require a 'bigger turn' to get the same slide movement. You can change to a G2 or YZ throttle tube to change this.


I chose starting with a 2008 rather than the new FI models, because the older bikes have a larger cockpit. 

Otherwise, I would have just gone 'new' with my project.


...and I wouldn't worry much about the weight, because it handles so much better than the 'lighter' enduro bikes, which when full of gas, are only 11lbs apart.....


Edited by TheKoolAidMadeMeSick

Yeah, I actually like the handling for woods. It's a friends bike, but I spend almost as much time on it as him. We all just kind if trade in and out. I'm not looking to make a motocrosser out of it, just wanted that harder hit and quicker rev. Y'all have definitely given me some good options to look at. Thanks for the input.

Did you put on the JD jet kit if not I would try that. It make for a snappier bike. Just did one last week. Used the red needle and with the 45, 168 pilot and main. The bike had a GYTR needle to begin with.

The header pipe diameter might be restricting it

Dunno about the 06, but the AL frame models, Yamaha reduce the diameter to give it more low end torque at the expense of top end power

Hotcams will perk that thing up.  The bike will run like a YZ with a heavy flywheel.

I agree with Koolaid and Beezer.  Did the YZ Hotcams with a clean-up port job and a .5 bump in piston and it really seemed to give it the extra pop I was looking for :thumbsup:

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