What's light weight to you? Coming from a ST it could be 400 lbs... Also two stroke or four? Price range? I-90 Motorsports has a nice 350 exc demo you might want to throw a leg over, but be prepared, the way they have it set up it'll run ya well over 10k out the door. At Roscoe's last GG ride there was a very nicely done '12 street legal EC300 you might find interesting too. Don't remember who's it was but likely you can reach him here. KR, DR or XL 650 in the desert? Not on a bet... Not under my ass anyway.

Thanks everyone for your suggestions! I really want a street legal 4 stroke race bike under 300 lbs, 500 cc max suitable for riding the Odessa 100. Im on the fence about buying new versus used. I like the idea of a warranty but 4500 sounds better than 10k .

The Beta's are very interesting and the used 450 gasser with the Yamaha engine definitely has my attention but I'm a little concerned about parts and aftermarket accessories for those bikes. I briefly owened a husky te610 and really regret selling that bike and would consider getting a used te450. Since KTM bought husky I'm Again a little concerned about parts.

The xr 600/650 is a proven steed for the desert 4-sure and in the right hands can blast through the woods but Unfortunatley I don't have those skills. I can remember hopelessly attempting to keep up with Scott Summers on his XR 600 back in the late 80's . He rode that bike like it was on rails!

All of the magazines rave about the KTM 500 EXC and so far I Haven't found any major complaints about them other than filter/EFI issues with 2012 models which I think KTM resolved.

Yup so many choices :D

ds bike
 

I know this is old,but.. You can't go wrong with a 350/500 EXC.Tasks had a a try legal TE300 not long ago. And it wouldn't take much to street legal your choice of off-road -Tasky's does the conversion if you don't want to deal with it.

A plated Yamaha WR450 is hard to beat. I've raced Enduros, Harescrambles, Trans America Trail, and will be doing some desert racing on it soon. It never breaks, has a great power spread, super stable, and if you are a good rider, can be just as fast as anything else. Here is mine.
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A guy I know has one of those KTM 500EXC's and he loves it. Pricey and high strung, but very nice.

I've had a lot of dual sports. Currently have a BMW F650. They are great but mostly for one road/dirt road stuff. I miss my WR250R for trails, plus I commuted 40 miles each way on the highway on it. Great little bikes.