Roll one wheel with the truck off the ground. See if the opposite whell spins in the oppisite direction. Feel for any clicking. If there is, its likely a 13th pinion gear missing a tooth or two
The three speed is cool. If you want to spenf the coin go that route. The hd is cheaper and a bit stronger. There is a beef up three speed thread here somewhere
I'm SV250 a mod there. The site was having problems before the owner did a revamp. It was down a lot. After the revamp every member was supposed to get an email with inst. To reload their password. That project was a disaster. I haven't been able to access the site in a week. I'm tired of...
30% is fine. Med plug is best but will run on a hot plug. It will gave more low end the top.
The coils are smashed shrunk and red because you are running lean. Thats it. A decent tune will fix you problems.
Now mixing fuels is a bad idea. Every fuel co has their own recipe for oil, methane...