Getting a cadet ready for Yamaha Junior sportsman/rookie and I’m going to have to add around 30-40 lbs of lead. Had a guy tell me they use to put lead shot in the chassis back in the 70’s and 80’s. The way he explained it, sounds like a great idea but I am skeptical. I realize the chassis are made different now, can anybody chime in on this? Good, bad, or indifferent.
You are going to get a lot of responses both ways. Lots of people will tell you the chassis won’t flex. I can tell you that I have won many roadraces in the past with a shot filled chassis. On a full size kart it was worth about 12-14 lbs if I remember correctly. It’s not to difucult to try at the very least.
We did it when we ran rookie but knowing what I know now, I wouldn’t. It might not be as big of a deal in a slower class or in road racing like Jim noted, but you’re going to alter the flex of the chassis a bit. And it’s also probably illegal some places because of the risk of getting a leak and having lead shot spill out onto the track.
Used shot in my son’s kart when he was a novice. Wouldn’t do it today. Beside the fact that it might alter the way the chassis flexes, consider what woulld happen if you lost your rear bumper and dumped little round balls on the track.
I have used it before, but can’t say definitively how the chassis reacted to it. It was in fact worth 14lbs, but as everyone states – a really bad day for everyone if your bumper falls off. If you use the option, pour some hot wax in the ends after your shot. Easy to get out, but holds in the shot if the bumper gets lost.