Well both of us are imitating motorcycles, so it would even be very hard to write down the actual ‘melody’ to compare both. As said by others, it’s also an easy and common thing to do on guitar. Plus both sounds are rythmically a bit different : Motley Crue do not have the fast bit at the beginning of Montrose, they do 3 bends rather than 4 and they are a bit slower. It still may be technically plagiarism but it would be on a very small scale