Hi all. First post and I figured I'd throw my problems to the pros in search of a little advice. I bought an 03 YZ450F in pieces. The bottom end had seized and the kid took it apart. He got to splitting the case and quit as he had just done a top end rebuild on it. The kids dad did a good job labeling things and so I took it for a good price. I rebuilt the bottom with the Wiseco crank set and finally got it back together on Sunday. Got it fired up after a few hard tries. Seems that it's popping and backfiring, the kickstart fires back at me, and it won't idle. I'm thinking a dirty carb since it was out of commission for a good 6 months. Any thoughts? Also, really worrying me, the bike sounds like its knocking. I've seen other posts that state the bike sounds like that but it's bothering me. Just curious as to any other owners. I haven't touched a bike since I was 12 so I want to make sure it's good to go. Any help would be awesome.