Are you stock or jetted? When mine was stock I had to rev it to at least 5k to avoid lugging in the next gear. After the holeshot mods, I can shift around 4k (a little less on level ground). Real power hits around 8k, for a 600 it makes decent power when you get around 10k. This motor is very durable. I only have 10k mi. on mine but it runs great and i've never had to add oil between changes.