I have an 07 Race Replica 450 Sherco. I went to check the valves today as it was becoming harder to start on checking the inlet clearance i find 0 gap the exhausts are at 0.25 mm. I have rotated the engine to all positions and there is no way i can gain any clearance on the inlet valves. On removing the shim buckets i find the are they smallest available part # 0730 = 1.55 mm I am assuming the head must come off and head work done ie valves seats and valves along with anything else folks here would suggest. New cam chain while i'm there? Is it necessary to get the tool for breaking the chain? Am asking for any suggestions folks may have. Is it possible to remove the head with engine in place ? I know this thread is kinda dead but hope someone checks it from time to time.