I replaced the collapsed lifter this past weekend, got everything back together, and now it all runs much better.

While replacing the lifter, I discovered a couple things. 1. The cam lobe was a bit worn. Not much, but noticeable. Then, I also noticed those jeep lifters that are a $3 alternative to the $125 lifters from the yamaha dealer are a different height. The jeep lifter is roughly 1/16th of an inch shorter. I should have measured with my micrometer before I put it in, but I wasn't thinking at the time. Well, that combined with the slightly worn lobe, and I'm talking less than .3mm of wear off the lobe, there's a noticable difference.

Now, when I'm out riding, I noticed a couple things.
1. The R* is fast as hell. Seriously, I got it running on one 800cc cylinder. Something sounded missing, but I didn't think it was a whole cylinder, just bad combustion or something on one of them. I had mentioned that my top speed was about 70mph, it was hard to get faster than that. I found myself accidentally doing 70 in 3rd gear about 50ft after turning on to a side road. There's a huge steep mile long hill, called mile hill. It's a pretty steep grade too. I was in 4th doing 50 up it, rolled the throttle, and it just roared and shot me up the hill extremely quickly.

2. I had a terrible tapping noise coming from the engine. My best guess is the rocker arm for the intake cam slapping against the valves, because of the clearance created by the shorter lifter, the shorter cam. Can anyone say whether this is probably it or if it's something else? It's pretty loud. Will this tapping damage anything if it's the rocker it's tapping against? I was thinking about adjustable pushrods, telescoping pushrod covers for adjustment without removing the top layers of hte head, new cams, and new lifters all around as a winter project.