Racer X Tested: 2007 YZ450

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2007 YZ450: A return from the Dead!
Like it or not the 4-strokes are a way of the life for us now and they are great in many ways on the track and trail.  However, one big downside is that when a good 4-stoke motor goes south it means serious $$.  There are many cases where it will cost as much or more than a bike is worth to repair.  Well, with the help of a few good companies we were able to fix up a very good YZ450 that was headed to the dumpster.
The bike was purchased for only $300 off Craigslist and that might sound tremendous on the surface however, if you add in the approximately $2000 to get parts for the engine and repair the suspension it is not as tremendous.  Sometimes even a free bike can be worth just that (nothing).   

When you looking to pick up a damaged current 4-stroke look for ones with good cases and head.  These parts cost way too much stock in most cases to consider replacing. 

For this project we needed a full rebuild with a Hot Rods Bottom end kit that too care of our lower end and a Cylinder Works std bore std compression top end kit.  These two kits took care of our main problems.  Then we got new OEM valves and springs from Yamaha. 

The stock pipe was in great shape and could have been used if staying on a tighter budget but were looking for a bit more performance so went with the FMF system in Stainless.

The suspension was just freshened up with some fresh Pivot Works bearings and seals and oil. MB1 took good care of us with this. 

To make this thing look like it wasn’t five years old we went to MX Plastics and get a bit of a retro look and had Decal Works give it that Henry look. 

Our initial ride has us a slight bit off on the carb and it turns out it needed one more good cleaning.   On any old bike that has been sitting you can count on that every passage could be blocked and we missed one.   Now it runs like a new bike with over 15 hours on the bike since the build we can’t complain.   Tom Morgan helped us get the jetting specs just right.

Overall it was a great project that shows that you can fix up about any bike if you have the time, resources and money to do so.


Rocky Mountain ATV/MC             www.rockymountainatvmc.com 800-336-5437
Just about every part listed below

Hot Rods                                           www.hotrodsproducts.com    515-402-8100
Complete Bottom end kit
Includes complete crankshaft, main bearing seal kit and complete engine gasket kit.            


Cylinder Works                                 www.cylinder-works.com      515-251-4070
Complete std bore and std compression cylinder kit    
Includes Cylinder, forged Vertex Piston and Cometic Top-End gasket kit

Hot Cams                                           www.hotcamsinc.com            515-402-8200
Stage two cam set

FMF Racing                                      www.fmfracing.com               310-631-4363            
Full Stainless Steel system

CV4                                                    www.cv4.net                          800-874-1223            
Formed Silicone Coolant hoses in white

TMR                                                   www.morganracingengines.com  949-421-7112
Jetting specs

Pivot Works                           www.pivotworks.com                        515-402-8000
Steering stem bearing kit      
Fork Rebuild kit
Shock rebuild kit

Uni Filter                                            www.unifilter.com                  714-535-6933
Two-Stage air filter

Renthal                                               www.renthal.com                   877-736-8425
Front Sprocket
Twin Ring rear sprocket           
O-Ring Chain                               
997 Twin Walls
Dual compound grips

Dunlop Tire                                       www.dunlopmotorcycle.com 800-845-8378
MX 51 front  
MX 51 rear 

MX Plastics                                        www.mxplastic.com               800-843-8244
All new Plastic kit                 
DeCal Works                                     www.decalmx.com                    815-784-4000
Semi-Custom Graphics kit                  
Pre printed number plates backgrounds 

Moto Seat                                           www.motoseat.com               951-258-5229
Custom Cool seat cover

Works Connection                            www.worksconnection.com   1-800-349-1475
Elite Clutch Perch                 
Stand