sounds like low oil pressure on idle or the tappets have had it so when u changed the oil when u started it with new oil the tappets draind before the new oil got there cos the seals have gone...just a idea
top weekend over did it on the preping of my head with to mutch beer got 5 runs in my best 14.6 got fedup with waiting and felt well ill so gave it to liam he got 14.4 so it proves to mutch beer makes me slower..o well
sounds like a seized caliper and it dont cost to mutch to do the rear bearings remove h brake cable from the caliper if it stays on its the caliper if it goes of its the cable