None of the 85's are great for that type of use out of the box. BUT any of them can be made pretty good or even really good for trail riding given the proper modifications.
We took what was known as one of the most unruly 85's and made it in to a great bike for trail that is easily switched over to a VERY capible track bike. The 2003 CR85R we started with had a crazy hit and I held little hope of it being even reasonable in the trees but my son was insistant he wanted red. So I found a solid used example and we hatched a plan to make it what we wanted. Well some carefully planned modifications from some primo companies and I was amazed. We talked with Eric Gorr and decided on a big bore engine with porting and head modifications combined with a FMF Fatty and Turbine Core 2 (USFS spark arrestor) exhaust and Steahly flywheel weight did wonders!!! Eric sent me a extra capacity Fluidyne radiator to help make sure things stayed cool in the tight stuff which is often overlooked and a big issue with the little screamers. We then had the suspension tuned for him and put it all back together with fresh paint, bearings, seals, plastic, etc... It really is a very good trail bike now that has plenty of power everywhere and is not prone to stalling. Spend 10-15 minutes to pull the flywheel weight and the bike transforms in to a super mini that can run with any of them.
The real bummer is that after 1 season my son had a growth spurt and is now too big for the bike so it needs to go and I have to do it all over again :bang: