I have a '96 DR350SE with 14000 miles and I'm riding with bigger bikes on the HWY loaded for a multi day ride and was wondering if I'm hurting the engine by running it at about 60 miles/hr on the HWY for ~300-500 miles/day? I have a stock rear sprocket and a 14 tooth up front (15 is stock). I went over the weigh scales with a full Acerbis tank of fuel (4.2 gal) and my multi day trip gear, the bike with that gear weighed 440lbs. I weigh about 200lbs on top of that.I'm running the narrower 4.6x18 Kenda K270 rear tire.I've been impressed with the engine's power on the HWY as I could sustain the 60 mph in 6th gear up a long steep HWY hill. My fuel economy on the HWY is about the same as the loaded KLR 650 I was riding with so I was worried I may be running the motor too hard and causing it harm (I have the pumper carb installed, 1/2 of the air box open with a No Toil air filter and the stock needle). The bike does cough and fart a bit at the top end of the rpm range under load so I have to work on the air to fuel mixture still (ie: cover off more/less of the air box top).One other question: I installed the 4.6x18 kenda rear tire and it was very skinny versus the previous 4.5x18. If I go back to the 4.5x18 what sort of performance changes might I find (ie: will I have less power with the wider tire, will I get different gas milage, or longer tire wear etc)? I know the 4.5 is a 6 ply versus the 4 ply of the 4.6 so the 4.5 will be heavier as well.I was at a Horizons Unlimited meeting last weekend and I started to think about getting a more powerful bike for the multi day trips I do which has lots of HWY pavement riding to get to the good dirt. There is not much to choose from out there in the smaller/lighter platform which I want given my weak off road skills. I had a KLR before but I found it too heavy and it went to sleep very easily thus the lighter DR. I was thinking about the DRZ or the DR650, but the DRZ seems to be more dirt orientated (I don't have a problem running the DR350 on the HWY for long periods from a comfort point of view) and the 650 is a bigger heavier bike and neither of them have the 6th gear like the smaller 350. If I'm not doing any damage to the 350 with my high speed HWY riding then I might just stick with the 350.Thanks very much.