I recently bought my first kart - a used Praga Dragon with a 206. From what I read (and please correct me if this is wrong) the big reason for a different chassis for a 2-stroke vs. 4-stroke is that the 2-stroke chassis tend to be a bit stiffer due to the higher speeds. Along these lines, I looked at each of the Briggs classes this weekend at my local track (GoPro, now Trackhouse), and I did not see a single one running with seat stays, and I was told this was also because the stays make it too stiff.
I bought my kart with a Jecko D7 seat, and I recently did my first morning with a C5 plus two seat stays going to the bearings (one per side, the previous two mornings were in the original seat and no stays). The kart rotated SO much more readily, I looped twice on my warmup lap. Once I acclimated though, I did my best times yet by about 5 seconds which really doesn’t mean much. Without the stays and with the larger seat, I could feel the chassis flexing aft of the seat, a sort of roll axis oscillation after catching a slide. Predictably, that went entirely away with the new seat and stays. Overall though, once I got past the initial lap, I really thought it felt good
So now my question: is this just a case of a negative times a negative making a positive? The two negatives being a bad driver in a bad kart working together better than said bad driver in a better set up kart? Or is there something I am missing? It seems other 206 karts run seat stays at other tracks when I google it, so is this just a GoPro-specific thing? If so, why? I find it very strange that, if it is stiffer due to being a 2-stroke chassis (30mm tubing, 50mm OD axle), why did it feel like a wet noodle? I am much smaller than the original owner, and I am not running lead yet, so if anything I’d expect it to be overly stiff as I received it, but it certainly hasn’t felt that way.
My best guess is that, with me being 30lbs under weight, I need more ‘help’ transferring load to the outside rear, and the stays help me do just that. But then again, the Jr class is my weight and also did not have anyone running stays from what I could tell. The bottom line is that I liked how it felt, and I am nowhere consistent enough yet to play with tuning. I only included them in the first place since I thought they were supposed to be used for a baseline, so I plan on keeping this as my baseline for a while. Still, I want to understand what’s going on here.
PS: This is somewhat a continuation of this older thread: Masters [email protected], CHASSIS HANDLING ISSUE - #8 by CrocIndy