Kahuku Motocross has been open to mountain biking for awhile but because of its isolation on the North Shore it doesn't see much mountain bike traffic. Earlier this year (2011) the park was opened up to Mountain Bike Racing.
The park is located on Oahu's North Shore, about half a mile from the famous Sunset Beach. Once you pull off of Kamehameha Hwy you will drive a couple of miles up into the park where there is plenty of parking. The track is open on Saturdays, Sundays and Holidays from 8:00am to 6:00pm. There is a daily riding fee of $10 dollars, or $5 if you purchase the annual pass. The annual pass costs $30 and is available to purchase at Kahuku Motocross.
To learn more about the Moto Track visit the Hawaii Motorsports Association's website: www.ridehma.com.
Once you leave Kamehameha Hwy and turn up to the mountain you'll be on a jeep road. Although rough, the road is in good enough condition for small cars to drive on. On wet raining days the road because slick and muddy.
I love riding at Kahuku. You can ride downhill the whole morning, BBQ at lunch and finish up the day running all-mountain lines or chilling with some relaxing cross country. If you go with friends you can shuttle most of the way to the top. The downhill terrain is steep, in the trees and all natural. You will be riding dirt bike trails so rough and off-camber. The all-mountain lines are fast and flowy with challenging downhill sections. There is beautiful single track everywhere. The place is so big you can just make up whatever lines you want.
Clicking on the link above you bring you to Google Maps where directions to the trail are plotted in from Honolulu Airport.
Download the GPX file and use your favorite software to upload trail data to your GPS. Right click on the link and select "Save Link As..." in order to download it.