The 1x XR650R had many different configurations tried by Bob Bell and Honda and it is almost impossible to know exactly what the 2005 Baja 1000 winning bike had going on inside the motor.
From my research I have ascertained that some amount of porting and polishing was done on the internals of the head, they fitted the HRC kit pictured below, minus the high compression piston (apparently to reduce power slightly as they were struggling with traction). There were air intake mods like the HRC airbox cover mod and something called a 'Bat Wing' which was an aluminium scoop inside the air box to smooth air flow into the carb. They also had the CDI tweaked to increase the rev limiter and produce better characteristics for desert racing.
Bad news is the motor is one area that I didn't modify internally from my already modified but sad looking XRR motor
There are a few reasons for this. Firstly I can't find an HRC kit, they were discontinued years ago, secondly my motor already has a Stage 1 Hotcams and Vortex programmable CDI fitted and I feel that it already has the punch to make this bike a scream to ride and it was done not long ago.
I will however be adding a Pro Circuit reverse megaphone race exhaust system and the Bat Wing mod to make it closer to the original 1x bike. If I come across an HRC kit one day, I will jump on it and do the motor justice by fitting it, but for now I am being realistic and moving on.
Now, the other aspect of the motor is how it looks. As you can see my poor old XR had a tired looking motor and it needed some freshening up. I started by removing it
I blanked everything off and used a solution of aluminium cleaner and water to scrub the casings all over. After many hours it came up looking as fresh as a new one! As with the rest of the bike I also removed visible bolts one at a time and polished them with my Dremel
. I also got new clutch and stator covers which makes a big difference visually!
And here is the finished product:
And here is a Precision Concepts motor (not the 1x but similar):
For more on the Bat Wing mod please see my future posts