On June 4th we rode from Boston Bar to Nahatlatch Lake, then up Kookipi from the Nahatlatch side for about 16km...just under the 1,000M elevation(GPS died, so not much precision) and the road was fine, in fact a Jeep Cherokee was up there. Unfortunately time intervened and we retreated back to BBar. As for the Nahatlatch, the bridge at the 40 km Up marker (or nearest) is out, but a DRZ400 could get around the obstacle fairly easy, even easier with another strong pair of hands. Bigger ADV bikes would take either take an abundance of skill or 2-3 grunts with a bit of motivation. There has been machine work on both sides and the creek would be easier to cross if they hadn't attempted to block it with logs. I have pics, can't post 'em, but if anybody needs better detail, just shoot me a message/email.