1 & 3 are definitely Mallory Park on the hairpin exit. 2 would be Creg Ny Baa and obviously Ballaugh for 4. Pic 4 would be the 750cc sidecar race as denoted by the black plates and it looks like there's a BSA sticker on the fairing. I wonder if it's Peter Sheridan & Philip Smith, both sadly lost in an awful accident at Oulton in 1971. My dad gave them a tow back to the paddock after they broke down in practice and if I remember right, they had a white outfit. They were entered on a BSA in the 1970 750 sidecar TT. Pic 2 is a 500cc outfit (yellow plates) and looking at the colour scheme, I'm thinking it might be the Woodhouse brothers. All this is just guesswork on my part!

I've put a link to this thread on Steve's Place where all the sidecar guys hang out, so maybe we can get a positive ID.