Sean Colliers KX500 Project "I was only going to inspect the top end"

[USMC 500]

So here is a little info on the wheels and swing arm. After my buddy Tommy Roberts mounted the new rubber I found a few loose spokes and tightened them. Thanks to Pivot Works I had all the bearing kits needed for the steering stem, both wheels, shock, shock linkage and the swing arm. Scrubbed down the swing arm with some degreaser and a Scotchbrite pad.......Inspected and tightened the rim locks using a torque wrench and mounted a new 45 tooth rear sprocket. With all new bearings throughout the bike, new tires and all the love and attention to detail from the boys of KX Guru Racing, the Beast will be better than new.

Story on the sprockets........

Sean was running typical MX gearing 14/51. The 51 tooth rear sprocket was large to the point that it would drag the chain at a downward angle across the bottom of the chain guide. The chain had finally eaten through the lower chain guide slider, both bolts and completely out the bottom of the chain guide during our last ride. Fortunately I had this chain guide and 2 others on hand. I was able to make one really good serviceable chain guide out of the 3 and that's what's on there now. Talk about a budget build!! But it is solid, mechanically sound and not bad looking.

During the KX Guru Racing test session I had with Sean (video link below) he rode my bike with 13/45 gearing and absolutely loved it. He said that he could feel the chain rub on his bike and not on mine. He also liked the shifting characteristic and power delivery that my KX500 had with 13/45 gearing and stated that he wanted that same gearing on the Beast. With a 45 tooth on the rear we should eliminate the issue of the chain drag across the bottom of the chain guide at such an extreme angle.

https://youtu.be/U1m3jJgygC4

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A word about bearings.
The bearings in this engine were a little over a year old.
Most seemed to be ok.
But what does that really mean?
How reliable are they?
Here is a short clip of Jason at JT Engine Works and I discussing the bearings.

https://www.youtube.com/watch?v=m1MBjrWXlEk

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The next item was the head.
After Vapor Blasting the head we baked it for about 30 minutes at 200F to be sure all the water that gets pushed into the pours of the surface metal was completely gone.

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After baking I went ahead and semi polished the combustion chamber.
I didn't put a high polish on it because we will be completely rebuilding this engine in a few months and make it something to be respected on the MX track.

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Here is several shots of the engine...

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When I tell people that our builds are like giving away our children I was only joking

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Carburetion....
It was dirty and the floats were too low causing a lean condition.
It is a very common problem.
But after a bit of time we were able to make it ready to go again..
We disassembled, Vapor blasted, Cleaned everything spotless, polished the slide, set the float height and reassembled using the same settings the carb had to begin with.
Yes, we actually record before disassembly

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