My question to you is which screw is used to adjusted on the 2 speed. I don't want to adjust the wrong one and have my 2 speed fall apart.
You will be adjusting the black screw. Your manual says
this in Section 8. If you adjusted the silver screw, take the silver screw
out and make sure it's screwed onto the flat spot on the #25016 two-speed
shaft. If it is not, the two-speed will not work properly. See your manual
if you need more info.
I am on my 5th tank and it won't shift into second gear. What do you suggest doing?
After only five tanks of fuel your engine is not broken
in. If your truck was shifting during the first couple of tanks you were
running the truck too hard to start with. You will want to continue
breaking in the engine and loosen the two-speed adjustment.
Does the shifting to second gear makes an audible sound?
You will hear a change in engine note as the engine
note drops slightly before picking up the revs again.