Re: WHAT MOTOR DO I HAVE and IS 38mm or 40mm stroke better ?
Sounds like your tach is counting half for a 2cyl or something. You need to go into the settings and set it to a single cylinder. as for the other questions I can't help you there. Wide open you should be reading closer to 10k not 5k.
Can I make a suggestion? Split your post up into paragraphs to make it easier to read (like this) you will have a higher chance of getting all your q's answered.
I don't always listen to Alice in Chains..... but when I do, SO DO THE NEIGHBORS