Don't know if anyone is still out there on this... Those pictures are great, what a much better, simpler time to be alive and just lovin' life and having fun!
The last AMA/FIM pro race there was the 1981 Trans USA. The great fans that always got out-of-hand (which was GREAT!) unfortunately went overboard and burnt down the AMA/FIM Tech Inspection shed during the summer 125 GP weekend with all the AMA/FIM records and test equipment in it was the final nail. After the fall Trans USA race that was it... so sad. I believe By 80 they had put a ban on any fan dirt bikes being brought in. They had changed the track by 80, they took out the back two rabbit rabbit ear loops and the back parking/fan track oval. The back area was a corn field in 81.
Remember in 77 the Russians are coming the Russians are coming (on CZs)! Gaston took care of them for NATO!
They had an off road truck race Saturday afternoon at the 81 Trans USA race on a track laid out in a field and Marty Smith with Marty Moates as a passenger got second place in at Pontiac Firebird rental car! It was an unbelievable site seeing Marty S fly the car off jumps hauling total ass with Marty M hanging out the passenger window with his thumbs up. Marty S, his wife and another couple died a couple year ago doing the same type of driving in a 700 HP 4 seat sand buggy in the California desert, RIP. Anyone who ever saw Marty race at Mid-Ohio knows he was truly one of the greatest of all time, his style has and will never be surpassed.
I will never forget that and may other unofficial events. Around the clock dirt bike fan races, some times dirt bikes vs 4x4s, 4x4 hill climbs, mud runs. tug of wars. Mud, beer and driveshafts flying everywhere! I remember at night a tug-of-war in mud that cost a 4x4 it's drive live, I would say 1K plus cans all flick their BICs and started chanting "BURN IT, BURN IT" the drive was pleading for help to pull it out and get away! There were giant left over furniture bon fires that probably could be seen from Mansfield! There was always so much out of control s**t going on luck no one was ever killed (at least that I know of)!
By the way the first picture of the 77 RM 100 looks like a cheater 100, an 77 RM 100 motor in an RM 125 frame. I RM 100 did not have leading axle forks until 78 and they did not have that much slider below the axle even in 78. I started racing in the D11 School Boy class on an 78 RM 100, the suspension on the cheater 100s was way better. Even the cheater 100s could not compete against the speed and skill of Mike Bias is D11 School Boy, he was an unstoppable.
There was mention of the first AMA Pro National in Ohio, Honda Hills had Nationals in 74 and 75 I believe.