Preparations for September 9 race

Over the off weeks, I wanted to make two changes to the kart. First to the seat and second to the tachometer.  The first was to improve driver comfort, the second to improve our ability to analyze what was happening on the track and with lap times.

The seat issue as mentioned in the previous post has been bugging Lian for a few races where she found the back of her arm hitting the top of the seat where it wraps around her ribs.  Although the seat fits her well around the hips, it is a little too tall and her upper arm is getting bruised by the top of the seat.  This is a quality seat but seat makers don't seem to get the proportions right for the smaller drivers and it is just too tall.  The added padding to the seat bottom and back to move her shoulder away from the seat top only partially improved things.

Thinking a new seat was in order, Lian and I looked over the seat inventory at a local shop and found none that fit her better (the best fitting one was identical to the one we had).  Modifying the existing seat seems the only way to get her more comfort.  I considered cutting the seat top, shortening it, and re-attaching it with an extensive fiberglass patch.  In the end, I chose the less drastic path of adding yet more padding to the bottom.  We'll see if she likes it better.  Here is a shot of the additional layer of self-stick foam in the bottom.

Hopefully, this won't change the CG shift in the turns very much.  This is a distraction I wanted to eliminate for our driver.

As for the tachometer, it is giving good data as far as the rpm but I wanted more.  With engine tuning, I wanted to operate it as hot as I could without compromising engine life.  The old tach is capable of giving me the engine temperature at the base of the spark plug but the kart did not have this sensor installed.  When I investigated a replacement sensor for this old gauge, I made an important discovery.  The engine temp sensor that works with our old gauge does not fit our newer engine (without rule-violating modifications to the engine).  A new gauge was in order.  Here is the old instrument with it's simple, two -window display.

The new standard for Karting instruments is the Mychron 4 tachometer which has not only a tach and temp sensor that fits, but also an optical sensor.  The sensor is for an infra-red beacon setup trackside (usually at the start/finish line) that starts and stops the internal timer.  This feature allows it to record lap times error free!  Mom won't have to fumble with a stopwatch anymore.  This was not inexpensive but it was needed to step-up our game.  Here is what the new gizmo looks like mounted on Lian's steering wheel.

It was a little bit of a chore to install, mostly because there was a modification needed to the engine air shroud near the spark plug.  I didn't want to do the cutting with this still on the engine so a few hours worth of disassembly and re-assembly and about 10 minutes of cutting and filing got the job done right.  Now it is giving me what I need to squeeze the max from our trusty Briggs & Stratton engine.

Next post - the results at the track...