Wondering if there’s a consensus on how much weight impacts lap times?
So many variables hard to say. Figure a tenth for every 25lbs.
Different opinions incoming, I suspect. 
Guessing here, but I would say adding that amount of weight for that circuit may result in a difference of four or five tenths per lap.
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My rule is more like .1 for every 10 pounds. This comes from years of experience running both the Light and Heavy classes in one weekend for Manufacturer’s Cup. Light class (320lbs) was typically about .5 faster than Heavy (360lbs).
The moderator on K-Racer (Australia) has a really detailed analysis in a video at K Racer-YouTube entitled “Weight/Time Penalty.”
Re: My earlier post. If I’m doing the math correctly, our friend from Australia figured about about 0.14 sec. per 10 pounds – and even more on a long, high speed track. More than I expected – anyone want to check my numbers?
I run Tag Master and weigh in around 415 lbs (kart 190/driver 225). My Class/Engine weight is 390 lbs ('09 Leopard). We generally run with the Senior Class, mostly X30’s. Their weight is 370 vs Master X30 of 400 lbs. My last race, I was almost 3 full seconds slower than the leader. In theory, I should be within 0.7 of them. I really need to work on my driving!!!..and maybe finding a more powerful engine package…lol!
My daughter lives about 3 hours from that track, last time I visited her I stopped by for a spin on their 2 strokes. Quite a twisty track, weight wise you need to find the best acceleration balance though - you’ll find you’re running a tooth or two higher than the lighter guys to pull you out of the corners, but then you’re compromised on the straights. Nice track.
It won’t be much of a disadvantage because the straights are so short.
I had the same thought. I picked up a few taller rear sprockets and have swapped them out a few times. At first I was shooting for a low rpm target out of the slowest corners to be in the 8000 -8200 range. It definitely helped my consistency of lap times. Before when I was gearing for peak rpm, if I didn’t nail a corner just right, I would loose tons of time building back up speed. It feels much faster off the corners now, but there is still time to be found.
I usually go into free practice somewhere near the right sprocket, don’t do anything until I’ve done a few runs, stabilized my lap time consistency and got the tyre pressures sorted out, then go up and down a couple of teeth n see where the times go.