06/01/2026
At the last RAKC weekend Richie received a tech DQ. A bit about how an unaltered carb can fail tech and what you can do to ensure yours doesn't:
Richie has been running this particular carb on and off on a couple heads/motors since he started karting. It is stamped "WALBRO" instead of the current Briggs diamond logo. Now, just because it is stamped with Walbro does not make make this an illegal carb for Lo206 racing. In fact, rule 21 from Briggs states: "The B&S stock carburetor part #555658 is the only carburetor permitted. ‘Walbro’, ‘Briggs’ diamond logo and/or #590890 etched in the body are additional visual indicators."
Well and good! An unaltered carb will pass tech right? Well... not necessarily! Here's the bit I wish we would have known ahead of time!
The intake side of the carb "Venturi Horizontal Measurement" must be no larger than .602". This is measured with Briggs 206 tech tool A20. Some of these Walbro stamped carbs started life a bit larger in this measurement... but not necessarily out of tech. However, after many heat cycles eventually they can expand. Put simply... ours certainly did!
If you have one of these Walbro carbs I recommend asking tech to check this measurement during a practice session. Ask them to check the venturi width using tool A20. It is possible you may need a new carb but it is better to know!
Lastly, although it was very disappointing for myself (Tom) and Richie to get a DQ on an unaltered and (theoretically) legal carb, tech was very helpful and calmly explained the issue. Richie was even given a new replacement carb for our trouble.
Can't know what you don't know but I hope this post helps someone else avoid this particular pain point down the line. Good luck out there!
