99 rm 125 wont go into first gear at random times

[erklep]

split the cases and threw new bearings,seals,crank,and top end in. got everything buttoned up and filled her with fluids and broke it in just fine. every now and again during break in, it would give me a little fight going into first gear. drained and filled with clean fluids and still having the same issue.

so tonight i split the cases again to re-inspect the tranny and everything looks great with no wear and going by the manual, appears everything is in place correctly. it will upshift through all the gears perfect, and then downshift to neutral perfect. but about every 1 of 5 times, it will not let me in first. i realize i dont NEED first gear but it is nice to have.

the only thing i have noticed is that when it gets jammed up and wont drop into first, if i turn the counter shaft a bit, it will then drop into first gear like butter. its almost as if the teeth are laying on top of each other and when i turn the countershaft, the gear drops and meshes perfect.

any input is greatly appreciated....thanks guys!

* i purchased this bike with a blown top end, hence the full rebuild. so i do not know if this problem was present before the build. the previous owner seems honest and states that he never had any issues with the transmission.

-erik-

 

[jsantapau]

are you hand shifting it ona bench or is the problem actually when running? it is a strong possibility that the gears are just setting in the wrong spot of rotation ,that the dogs are in each others way when setting still , that you won't notice when it is running.

 

[erklep]

on a bench right now. i figured that it would shift differently on the bench versus running on the bike. i was thinking that mabye the gear had to be set in at a certain position so the dogs would align correctly when i downshift. i think im going to button it up tonight and see what happens. worse comes to worse, i split it open again.... im becomming a pro! hah

 

[erklep]

well, no luck with that. back to the drawing board! any ideas out there?

 

[erklep]

does anyone know if the shift shaft is suppossed to slide side to side with the side cover off(clutch side)?

with the sidecover removed, i can push the shift shaft to the right side of the bike to where it will not make contact with the roller on the shift drum. i see there is a stop on the backside of the sidecover to keep it from moving.

 

[erklep]

99 rm 125.... manual says 6 speed but i only have 5 gears.(1,N,2,3,4,5) 1st being the gear i cannot get it. am i also missing 6th gear? this could be a big clue in my problem.

 

[DisAintRcktScience]

You are going to want to look at the SHIFT FORKS them selfes and the gears in which the ride. if there is any wear at all on them this will cause them to not go into gear or even fall out of gear. if you find that the ends of the forks are worn out i would recommend replacing both the fork and the gear in which the fork moves or you will end up replacing the fork time and time again and in much shorter time.

 

[erklep]

well my manual came yesterday and after using my digital calipers and inspecting EVERYTHING, i come to find that i am missing a gear(2nd gear) and also the pins from the forks were sitting in the drum incorrectly. perhaps the reason the previous owner sold the bike so cheap. ordered my parts today and hopefully ill be on the trails by next week!

 

[GarbatyA4]

Awesome, good luck man!