Anthony had just painted the tank and sidecovers for his CB500.
On a ride, we noticed the carbs were overflowing a bit. Of course, the only logical thing to do was tear down the entire bike and rebuild it.
The bike, a pretty much stock ’72, is a good platform for low-cost, low-tech performance ‘upgrades’ for a decent increase in across the board power. We decided to use as much as we could that was original, or we had laying around.
These include a few CB650 parts, such as camshaft for a nice increase in midrange power with moderate low end and top end gains, and the oilpan for a slight increase in oil capacity.
We won’t document everything we do to the bike, but we will lay out some of the modifications made.
All of these photos have been me with my phone camera as I do this or that. At a later date, some of this will be replaced with better pictures and more descriptions.
First thing we did was have the bottom of the jugs decked a bit. This increases compression in this bike by around 9/10ths of a point.
I balanced and polished the pistons, and added some oil retention indents into the skirts. The cylinder sleeves were well within factory spec, so a quick hone was done and new rings installed. Cases painted a slightly metallic battleship grey.
We decided on a highly chip resistant paint for the frame and swingarm.
While the spokes were structurally sound, they were a bit tired looking. A quick powdercoating of the spokes, a dull luster ‘polished’ onto the hub, and a wheel truing on the wheels are an unassuming, nice look.
Some port-matching and clean-up of the intake plenums and carb boots. Carb boot rubber expands ever so slightly with heat, fuel and air, so leaving a tiny lip from boot to plenum will give you smooth airflow from carbs to head under running conditions.
For the hell of it, we powdercoated the plenums.
While doing some quick and dirty porting on the head, I found the valve seats to be unacceptable. I’ve put this head aside to do a higher end rebuild for another build.
More to come soon.
/edit: we havent touched the carbs yet...
