Thursday, May 13, 2010

May 8th Kart Practice at NTK

I made the trek to Dallas, TX this past weekend to practice in the shifter kart at North Texas Kartway. It's been over a month since I practiced in Midland so I was very anxious to have a productive weekend in the new kart. If you remember back to my April practice at Midland, I was having fuel delivery issues. I've been troubleshooting and ordering parts since then and it has been a frustrating process, but I believe the problem is now cured.

The root cause of the problem was excess epoxy from the pump-around carburetor modification clogged my fuel system. On shifter karts, it is common for the fuel system to be modified with a pump-around fuel pump that basically takes excess fuel from the carburetor bowl and pumps it back to the fuel tank. This is done to stabilize fuel level above the jets in the carb during high-G turns. To install the system, you must add an outlet from the float bowl that is epoxied to the carb to hold it in place. I found the problem by examining all of the fuel lines and inspecting the internals of the fuel pump and the carb. Here are two pictures:

Carb clogged with epoxy shavings

Clogged Fuel Line

To fix the problem, I replaced all of the fuel lines with new CRG line, installed a fuel filter between the tank and pump, rebuilt both sides of the fuel pump, and send the carburetor to The Kart Shop (where I purchased the kart) in Dallas to completely clean out my carb. I took my kart by TKS on Saturday morning to pick up my carb and the kart ran perfectly at their shop so I headed to NTK for practice. The engine started on the first try and everything seemed to be going well. While the engine was idling, I got my gear on and started to push the kart toward the hot pits when the engine died. After 3 hours and taking everything in the fuel system apart again, the engine finally started again around 7pm. I still do not know what the issue was, but I think part of it was my method of starting the engine. To start a shifter kart, you spin the rear axle by hand or with a pull-rope with the transmission in gear. I need a longer pull-rope - live and learn when switching to new equipment I guess.

I had an hour of light and made the best of it by finally getting on track in the new kart with a properly functioning engine. It was a blast! The Birel chassis handles very well - it is very balanced and easy to rotate in the corners. Being my first time in the kart and at this track, I struggled a bit at first finding the proper RPM range the motor can use and finding the right gear for each corner. After two sessions, I honed in on my shift points and was able to work on learning the track and learning how to be fast in this kart. I only did about 20 laps over 3 sessions before it got dark. I'm off the pace at this point, but learned enough in the 3-short sessions to help me get faster my next time at the track.

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