no problems, if you go extremely long, you will need a chain slider, but you dont need one up to about 8 inches, and keep you chain adjusted so its not slopping around. i did a +4" on my R and it made the bike much more rideable, and its still very trailable.
1985 Honda ATC250R drag trike with s/t kit and full drag CR hybrid motor and drag chassis...
1986 Honda ATC250R daily rider fully modded engine, +4 swinger,etc...
1997 Polaris Storm 800 triple, boyesen reeds, dg individual silencers, 240 studs, 123mph on radar...