1977 KZ400D.
Picked it up recently from a PO who was trying to fix it up but had no idea what he was doing. Got it all back in good shape, thoroughly cleaned the carbs... and I have a massive vacuum leak. 5K-6K RPM idle, put some RTV in the boot and between boot and the engine to see if it would help, and it did for a short period of time (this was meant to be a short-term fix, I wasn't 100% sure I had a vacuum leak in the first place because idle was so high that propane torch around this area didn't change engine speed noticeably, but it also didn't change it when put up to the actual air intake so) but after a minute or two the vacuum pressure must've been too much and ripped the RTV or something and it went back to 5K idle. Anyway, PO gave me two sets of boots, neither of which work great, and from a google search, it seems like what he gave me is really all you can find online, short of $60 old OEM ones that are cracked to hell. Point being, does anyone know of any good boots for a 1977 KZ400, or a better sealing solution than my RTV fix, or if I'm wrong and other things could be causing this. I've pretty much given up half the riding season to this carb issue and I'm starting to get pretty annoyed, I'm also attaching a video, the other issue with the bike is that when you roll on the throttle, too much air starts going in (I assume) it seriously bogs, but I'm pretty sure that's happening because of the vacuum leak. Any advice is welcome, thanks.
Video:
drive.google.com/file/d/1PFZETBcPg0PDzHE...XOl/view?usp=sharing
Two notes about the video: Not great at taking videos but anytime the RPMs increase, it's because I roll off the throttle, even if it doesn't seem so in the video. Also, this video was taken after I put another bead of RTV between engine and boots and let it cure, so unless it seriously can't hold up for more than a few minutes, I assume the leak is happening within the boot, not between boot and head.
