My 2001 CBR929RR has 57900 miles on it. It has been giving me trouble shifting into 2nd at high rpm for a while. Recently it has been rarely allowing me to get into 2nd gear at any rpm and when I do, it will pop back out of gear or slip into 3rd under acceleration.
I am planning to pull it out and replace the gears and shaft with a used set that is in better shape. Someone recently told me that using the wrong kind of oil might cause that. I'm using a synthetic oil recommended for that bike but I this due to be changed. Could worn out oil be part of my problem or is it certain that I have mechanical issues in the trans?
Also, if I buy a used trans and don't see any obvious visible damage to the gears can I assume its good?
Sounds more like a shift fork.
Would be worth inspecting the forks and shift drum before replacing the whole box.
When the oil is worn out a bike will often start complaining via the transmission first, but I doubt it'd only be in one gear.
As long as you understand what you're looking for, then yes.
Inspect all teeth for any pitting or wear marks or chips.
Inspect the dogs for any rounding, chipping and that the angles are ninety-degrees still.
Inspect all components for any blueing or other indications of heat, wear or damage.
Inspect the drum grooves for any blueing, wear, heat or damage and that the shift "points" are not worn or chipped. Make sure the bearings are nice and tight.
Inspect the forks for blueing, heat, wear and damage, and ensure they are at ninety-degrees to the shafts.
Inspect the fork shafts for any blueing or wear.
Inspect the shift shaft for damage, wear and ensure it is straight.