I used my bike for the first time in three months (injury lay off) and found there was no compression - I could move the kick start by hand. I had changed the oil and checked the valve clearances, swingarm headset lube etc (one armed maintenance) but not started it. After checking front to back, decomp action, spark plug etc I noted the compression was getting slightly better each kick - clammy valve? After about seven million kicks it started so I killed it and checked again, compression was back and it ran well, starting first kick. Any ideas?