DRZ400 adventure bike build

Back when I purchased my first DRZ400 to build up as an adventure bike I spent a lot of time researching different makes and models. The fact I do a lot of solo adventure riding means weight is a primary consideration. The terrain I prefer is technical and challenging so the bike needed to be off-road oriented. Riding in remote locations places importance on reliability; a kickstart is considered essential. The multi-day/week trips I do means that periods between oil changes and general maintenance etc was also a factor. 

Aftermarket part availability was crucial especially with the most important upgrade of a larger fuel tank to accommodate for the long distances between fuel stops. So, after weighing up a long list of pros and cons on many possible adventure bike candidates, a DRZ400E was selected.

To date I've racked up just shy of 100,000 km adventure riding a DRZ400. Although there have been some teething issues along the way, overall I couldn't be happier. A testament to this is that this build article is being completely rewritten as I have just purchased my third DRZ400 to be specifically built up using the RMOTO specs, and then freighted to Australia for a trip in June 2017. 

Photo 1 of DRZ400 adventure bike build
One of the many trips out on the DRZ400
Photo 2 of DRZ400 adventure bike build

Whilst the previous DRZ400 adventure bike build article was fairly basic on the details, this article will go into detail through every single step when building a DRZ400 into an adventure bike using the RMOTO specs. It is a work in progress but will be completed over the next 3 months as the bike must be completed and ready for shipping by May 2017.

2016 DRZ400E L7 strip down
Photo 3 of DRZ400 adventure bike build
For an older technology bike the suspension on the DRZ400 is fairly respectable. However it is sprung and set up for a midweight rider, not all the additional weight that comes with adventure riding such as extra fuel, water, tools, cooking gear, sleeping gear etc. With this in mind the first thing on the list was to strip the bike down and remove everything that needed to come off for upgrading plus pull out the suspension and send it off to Richard at Moto SR for a respring, revalve and 1 inch internal lowering.
Softening the DRZ400 throttle – Throttle return spring anchor relocation
Photo 4 of DRZ400 adventure bike build
The link below shows the process of how to reduce the tension of the throttle return spring and reduce fatigue on long riding days
Upgrading the Keihin FCR39 needle and main jet
Photo 5 of DRZ400 adventure bike build
After playing with a few different exhausts, needles and jetting combinations over the years I found a setup on the Keihin FCR39 that performs well for adventure riding. The needle is changed to a genuine Keihin FCR39 EMN (on the second clip groove) and the main jet is changed to a #160. The link below shows the process
Adding a hand tune pilot jet to the Keihin FCR39
Photo 6 of DRZ400 adventure bike build
There is nothing wrong with the standard Keihin FCR39 pilot jet (mixture screw) other than the fact it is tucked up into the carburettor body meaning it can't be easily accessed or tuned by hand. The link below shows the process of installing a hand tune pilot jet which will make life easy when making mixture adjustments.
Keihin FCR39 breather hose plumbing for deep water crossing
Photo 7 of DRZ400 adventure bike build
An upgrade to the Keihin FCR39 slant’s breather hoses must be made in order to successfully tackle deep water crossings. The link below shows the process of replumbing the breather hoses
Fitting a S/SM subframe
Photo 8 of DRZ400 adventure bike build
The DRZ400S/DRZ400SM subframe has foot peg mounts that fit the RemoteMoto luggage racks so a new SM subframe was fitted
3X3 airbox mod
Photo 9 of DRZ400 adventure bike build
The “3X3 airbox mod” is the opening up the airbox inlet to a size of 3 inches x 3 inches to increase airflow. Teamed up with upgraded jetting and a performance exhaust it provides a noticeable performance improvement.
Reference Link : DRZ400 3X3 Airbox Mod
Installing an oil temperature sensor
Photo 10 of DRZ400 adventure bike build
With aftermarket accessories that restrict the airflow across the engine and an increased luggage load, it can mean in the slow/steep/technical terrain, the engine temperature can rise above 100 degrees C. This is amplified on days where ambient temperatures are high. Because of this, I install both water and oil temperature sensors to monitor engine temperatures and make sure the engine temp stays at a healthy level. The link below shows the article on installing an oil sensor to the DRZ400
Installing a water temperature sensor
Photo 11 of DRZ400 adventure bike build
The DRZ400E doesn't have a water temperature sensor installed from factory and while the left radiator does have a threaded bleeder hole that can be used to screw in a temperature sensor, there are two reasons I prefer not to use this location. Firstly the cable on the temperature sensor makes it a hassle when you want to bleed the radiator system of air. Secondly the DRZ400 can get small air pockets in the left-hand radiator resulting in the temperature sender giving incorrect readings. The link below shows fitting a Trail Tech 19mm inline temperature sensor unit which is a far more reliable and accurate way of monitoring water temperatures and allows you to still use the left radiator air bleeder.
Side stand switch removal
Photo 12 of DRZ400 adventure bike build
Side stand switches are always on the hit list for removal when aiming to build the most reliable adventure bike possible. The link below shows the process of removing the DRZ400 side stand switch in a clean, tidy and reliable way.
SH775 regulator/rectifier upgrade
Photo 13 of DRZ400 adventure bike build
The link below explains how the upgrade to a SH775 regulator/rectifier improves reliability and increases voltage

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