well mine is roughly the same weight as a new 450. for such a old bike, and for the power they have, they are a very light bike. try find a bike with that much power/reliability that weighs less. mine weighed 112kg. im happy with that. but on the subject, old yamahas last forever but they get down on power. the newer yams are still reliable, but rebuilds are alot more expensive when you race and do taredowns every 50 hours. if your a woods rider, they are considered cheap and reliable. if you race, they can be expensive. (espec if you ride a crf) a 2stroke just costs $300 for a fresh top end. a 4 stroke needs up to $1000 and often needs professionals to build them correctly.they also go through bottom ends as quick as a 2poke. 2stroke needs piston reeds conrod. minimum labour. 4poke needs piston valves/valve seals head work (decarbon, cut valves,shimming etc) valve guides(sometimes) valve springs camchain oil and filters. AND A LOT OF LABOUR ! then there are fuel injection problems(blocked fuel filters,broken pumps, ecu mapping failures) and im not going to mention cams, cam chain tensioners, oil preassure, hard starting but they can be an issue sometimes. i can see why some people prefer the simplistic design of the 2poke. but there is not a real big cost difference if you just plod around. its only if you race them hard that they cost lots.. My experience with the older 400/426 is you have a lot more parts on your 4 stroke list than what is typically ever needed. The 99 400 I bought new and it was raced just about every weekend by myself in the 2 vet classes & my girlfriends son who raced it in 1 A class race & schoolboy. Mind you I ran top of the line oil (Spectro) and changed it every week and filter every other week. After 6 months checked the valves and they were spot on. After I year I was feeling guilty and pulled the top end down. After checking the piston & rings clearance there were still well within factory spec so I put it back together with only new gaskets. I did have the charging coil for the stator go bad but was able to source the coil only aftermarket. The 426 I had was bought used and came set up for Supermoto and had been road raced. When I bought it just so I knew where it stood I put a new top end in and that was it. I frequently practiced with it on a MX track with it and raced it 5 or 6 times a year. ......Again with good Spectro oil it was 100% bullet proof.