Where is 4th gear?!

[Skydiver86]

Just finished a complete top and bottom overhaul on my 2005 CRF250R. I bought this used and non running so I don't know if there were any prior issues. When I split the case I made sure the transmission came out intact. When I reinstalled it, I double checked the manual to ensure everything was in the correct order. Well, I just fired it up and took it for a test ride. Everything shifts fine, but when I shift into 4th gear, its like it goes into neutral. All the other gears work fine, its just the one gear that doesn't have anything to it. Any idea what could cause this??   

[97chevy]

When you shift into 4th gear and it feels like neutral, can you shift up again to get it in 5th? 

[Skydiver86]

Yup

[Skydiver86]

Nothing? Anybody??

[Fbabs]

During assembly did you check them?

I usually make sure it goes into each gear and I can feel each shift.

If you didn't check it, possibly the shift fork isn't engaged in the drum?

I would say the gear is not being moved.

You need to pull the clutch cover and make sure the shift drum is operating correctly (pay attention to the pawl)

Then you know if it's internal or not.

[Skydiver86]

I inspected everything closely. The gears were fine, no broken teeth, no obvious wear, and everything shifted and moved freely. That’s what’s got me stumped. It’s shifts all the way through perfectly fine, there’s no grinding, no nothing. Just 4th acts like neutral. 

[Fbabs]

What is kinda scary is if the gear is sitting there without being engaged in the fork, it could move over while you're in another gear.  This wouldn't be good.

Check the drum and go from there.

Fyi when I assemble any transmission, bike, car, truck, lawnmower, I always hold the output shaft to simulate load.  The reason is the oil friction alone will spin the countershaft, and fool you if the gears aren't meshed properly.