I just picked up a 01 YZ426F from a fellow TT member and all I can say is HOLY S$&@!!! I love this bike, it's a big improvement over the KX250 I've been riding. I read all the FAQs and just about every post related to the 426, but I have a few more questions: After struggling to start it in 30 degree weather, I realized the 03 cam is a must! The bike has a Thunder Alley pipe on it which sounds nice but is RIDICULOUSLY loud! Other than the pipe, it's bone stock. I want to freshen it up a bit while it's cold outside. Since I ride tight singletrack in the woods and do a harescramble 2-3 times a year, I'd like to put a bigger rear sprocket on it. What's a good setup for the 426? Does anyone make a flywheel weight for the 426? Is there anything I should look out for on the 01? I know the 00 426 had some issues with the clutch basket, but didn't see anything about the 01. Assuming the valves are still in spec, would there be any reason to replace them, or should I just keep checking them and leave them be as long as they stay in spec? Would there be any benefit in installing a new rings (just the rings, not the piston)? I like preventive maintenance, but don't see any reason in rebuilding the entire top end if it doesn't really need it. I can't wait to get back out on this bike!!! It makes me grin every time I hear that engine come to life!