Weight distribution

What is the weight distribution over the tires on a motocross bike with the rider standing on the pegs holding the handlebars. Is it 60% front 40% rear etc. I suspect its closer to 50-50. Granted the rider will have a significant effect as they lean foreward or back. For some reason the test mag articles never do this. It may be difficult to have a standard due to the riders effect. I do notice offset steering heads/ triple clamps and different length swing arms in the magazine adds. Whats the correct range for motocross racing for a given rider.

Thanks for the reply. As an engineer myself, many times compromises have to be made to satisfy the average customer. I know when I did durability work for Harley the bikes had to be ballasted x % on the front and x% on the rear to maintain a certain cg. I'd never expect it to be the same as on a dirt bike. As you see different size people run the same chasis you can see a 6' plus 260lb guy loads a bike differently that the typical 5'8" 150lb motocross racer. Being on the larger side myself I don't have to be off much with body position to auger a bike into the ground head first or tail first. Maybe I'd be better of with a longer wheelbase or move the handle bars or footpegs to get my cg in the right spot. Thanks in advance