Dirt Bikes and ATV's

Riding 2006 Yamaha Raptor 700 chasing a 2010 YZ 450 

at three palms "River Track"

(Click Youtube link in video to view in HD)

Riding 2006 Yamaha Raptor 700 chasing a 2010 YZ 450 

at three palms "Natural Track"

(Click Youtube link in video to view in HD)

2009 DRZ 400s

Modifications:     

• JD jet kit and Keintech adjustable pilot screw 
• (160 Main, 25pilot, 2.5 turns Out)
• Jetting Spreadsheet
• 3x3 mod (Cut 3" by 3" hole into airbox top lid to increase airflow)
• Air filter
• Valve Adjustment and Fluid Change
• 120/90x18 Dunlop D606 Rear Tire
• 90/90x21   Dunlop D606 Front Tire  

Jetting Spreadsheet from Thumper Talk

DRZ Thrust curves and Top Speed:

Like any good engineer I wanted to run the DRZ through my thrust curve and top speed spreadsheet.

Using Google images I downloaded an image of a stock DRZ400 dyno curve and back calculated the torque at each RPM. Using the service manual I input the gear ratios, primary reduction (crank to clutch), and final reduction ratios (countershaft to rear sprocket). I then calculated the tire diameter and was able to get speed and force curves for each gear and rpm. I also wanted to calculate accelerations in each gear so I took the DRZ400 wet weight, added my weight and went about calculating the drag forces. For this I took a front view of the drz and placed it into AutoCAD, scaled the image to the correct dimensions, and used an accepted motorcycle aero drag coefficient of .9. For Rolling resistance I just used 50lbs. A bit too much for slow speeds and probably a bit low for fast speeds. All this work yielded a top speed of 89 mph with 137lbs of drag.

Surprisingly, the calculations matched the GPS measured top speed of 88 mph almost exactly!

So now i have a good tool to see how gearing and power changes affect the bike......

Inputs

Frontal Area Calculation

Acceleration Curve

3x3 Mod

Valve Adjustment

Valve Clearances after 9000 miles 

JD jet kit

2006 Yamaha Raptor

Wet Weight (424 lbs)

Spreadsheet for Power Commander Enrichment Map
2006 Raptor 700 with Pro Design Intake and HMF Full Exhaust
(Note the 30% greater fuel requirement at 3500 RPM and 10% to Redline)