Not my first post, but just started posting a few days ago. I have never been on a bike, until I bought my 2013 DRZ400S two months ago. It had 2 miles on it when I bought it, and it now has almost 4,600 miles on it in the two months I've had it. Needless to say, I love riding, and I love this bike! At age 29 now, I don't know what took me so long to start riding (and find this bike...). Now on to the question - I have started standing up while riding, and I notice that sometimes when I'm standing, there's a violent lurch forward. This doesn't always happen, but it seems like there is a correlation between how full the tank is, and the likely-hood of occurance. I'm pretty sure this isn't normal, and it scares the crap out of me! Happens whether I'm going 45 or 85mph. Anyone have any clue? Thanks in advance! conway PS: I don't think it should matter, but I ride 95% freeway, and about 80% of that is speeds of 65mph - 85mph... Bike has been serviced at 800 and 4150 miles, with an intermittent oil change in between.