the 150 R is equipped with a 1/4 turn and the 150 F is not, the reason being is some guys here like to say R = race F = fun....... the 150F is more well suited to trails and everyday cruises and such.... can be ridden at the track, but if your gonna do that may aswell buy the race ready 150 R and use that... difference between the normal 150 and the expert is 19" front rim and 17" rear rim....opposed to the normal 150 with the 17" front 14" rear setup... I love these Hondas spent some time with them and really had fun stacking my cousins into a pond becasue the power was all right there on the "R"
also agree with the durability factor... they are very very durable and after i put it in the pond it was running 20 minutes later.... and just as good as before.... some minor things where done to ensure it would all be ok down the road aswell but it was all minor... the suspension feel of the CRF was very squishy and responsive with noticeable differences with different ammounts of pre-load... something my pit bike could not really do....
if you have a shot to get a CRF 150 for a decent price, dont pass up the opportunity... parts are everywhere.....