My ' Rule of thumb ' is to make sure I have enough money left, after the purchase of a bike, to deal with any problems that may crop up later.
Having said that, I hadn't anticipated having to source a second hand engine :blush: . Don't let that put you off. Mine's a four and I got shafted

by a dealer. Doh ! I had a Thunderbird triple and the engine can't be beaten for character. I say ' go for it ', you know you want to. :wink:
R.F.