10 Tips for the Honda XR600R by Scott Summers on 4Strokes.com

Here's what Scott Summers and Fred Bramblett (Scott's mechanic) do to their XR600R's to make them more competitive in closed course competition. Some of these tips can be applied to other model XR's as well.

To increase intake airflow, Scott removes the airbox snorkel and uses an aftermarket air filter. Scott recommends not removing the backfire screen from the air filter cage because it changes the intake air velocity and causes the bike to have poor throttle response at low rpm.

To increase exhaust flow, Scott replaces the stock muffler with an aftermarket unit with an open end-cap for closed course competition. Scott advises against using an open end-cap for trail riding, as it is too loud for use on public land. He also recommends sealing the muffler to the header junction with high temp sealant. Scott uses Hondaline Hondabond HT Sealant.

Check the header pipe where it mounts to the exhaust manifold. Sometimes the welds are overdone and the extra material can restrict airflow. Grind away the protruding material to increase flow, but don't overdo it to the point of making the area weak.

With the above mods, Scott uses the following jetting:

Main

Pilot

Air Screw

Stock

152

2-1/2 turns out

Modified

155

2-1/2 turns out

Scott says most four-strokes come jetted on the lean side and must be richened when you increase intake and exhaust flow.

To make his race bike run cooler and extend the clutch life, Scott mounts an XR250R oil cooler to the steering head and removes the headlight for more airflow.

For better cooling Scott sometimes wraps the header pipes with exhaust tape made by Thermo-Tech to keep heat from being transferred back into the cylinder and head by airflow.

On non-muddy terrain, Scott trims 4"-5" off the back of the front fender for better cylinder cooling.

Scott recommends against the use of plate-type skid plates. He feels they restrict air flow and trap engine heat.

Scott recommends good pump gas with an octane rating of at least 91, and higher if you have a heavily modified high compression engine. Scott runs a stock engine because the increased compression braking throws his timing off.

Scott recommends keeping your valves and decompression system adjusted often and properly. This is extremely important for any four-stroke dirt bike.

Credits: Content provided by Jeremy Hansen of The Unofficial Honda XR Page and edited by 4Strokes.com