I think this winter I am going to try and find a 650 motor and throw it in a quad frame. I am just not sure if I should go with the R or the L motor? Is there any difference in horsepower with the R or L? If anyone could get the height, width, and length of theirs I would really appreciate it. Do you think I would need to go liquid cooled, or would I be okay with air cooled? I will do a lot of tight trails and lots of open field riding, and I just need some of you guys that really know these motors to give me a little help if at all possible. I have a friend does a lot of crf450 conversions, and he said that if I get the dimensions we can see what we can fit in there. As you can see, I have lots of questions. Hopefully you will have some helpful ideas for me, and I really appreciate any help!!