How to gap plugs? H-D book say to use wire gauge @ .038"-.043". Whats wrong with the solid wheel with thick to thin gauge? Is wire easier & more accurate? Do you gap new plugs @ bottom, middle or top of the range?

 

Wire gauge is probably the easiest. Flat blades are probably the most accurate. I think that thick to thin solid wheel is probably the least accurate of all - I never had one of those but most of my experience with "universal" or multi-use tools is that they are handy in some cases but they don't do anything as good as the proper single purpose tool.

That said, a thou or two in either direction on plug gap is no big deal.

As far as the range in the gap is concerned, at the high end of the range you will get a bigger spark, while at the lower end of the range you may get a little crisper spark. There's probably a theoretical argument for either being slightly more beneficial than the other but in the real world it's unlikely that you'd see a difference.

My opinion based on all the previous mumbo-jumbo, gap 'em in the middle of the range with whatever tool you have and go!

 

^^^ What he said. A bit of variation really doesn't affect performance.

 

I'm not looking at the manual right now but my guess is that the tool they recommend is the wire type.
I set the gap to the middle of the range.

 

I've always used the flat blades, but 90% of the plugs you buy come gapped already, never had to regap. They're usually dead on.

 

I went to the Bosch "+4" Platinums; no need to gap and FOUR sparks per firing.