I have a RM 125 2000 the gear selector wouldn't spring its self back up when put in 1st gear but going up gears it spring its self back down but now its stuck in 2nd or 1st please help as i have just bought this bike

Question edited for clarity.
Question moved to Suzuki.

Normally caused by cracked return springs or bent selectors, but in your case, it's not. There is a shift kit available to fix the issue because it is well known.

http://www.factorypro.com/prod_pages/prods,rm-z250,07-13.html

https://www.google.com/search?q=2006+suzuki+rm-z250+shifting+problems

..

There are a few things to check. Engine and transmission mounts replace any broken or perished . 1st gear selector shaft has a indent ball and spring to locate the shaft when in gear, check the spring is not broken. The gear box bearings may be worn giving the drive shaft to much end play. also check gear shift linkage is not worn.

Adjust your selector cable. Put selecror in N. Loosen the nut of the cable on the tranny. Move the gearbox selector untill the two smole hles line up. Insert philips screwdriver in the holes and tighten your cable bolt securely.

Schweet

need to look at internal gear selector, may be bent, or springs damaged

the shifter return spring the one that makes the lever move back to the center somtimes break

you can ride the cluthch on a bike un like a car you wont hurt it its oil lubricated constantly, sitting on the bike pull the clutch in with your left hand and click the left foot lever down in to 1st, then learn how to click it back up 1 half movement in to neutral. the neutral light will come on sfter the bike enters neutral. in first gear give the throttle on the right hand a squeeze and pull the clutch in with your left hand put foot gear selector down in to 1 st and begin to release clutch slowly. hold on as bike will engage may be jerky balance yourself! when you get moving stop! by pulling the clutch in and the hand brake as you close the throttle to stop! practice your take off many times some where safe! when you get your balance in 1st gear pick up speed and begin shifting the foot gear selector up in to 2nd gear and practice closing the throttle and breaking to a safe stop. gears are generslly 1st down 1 click 2345 and6th all up from there and neutral is 1 half a click up from 1st between 2nd gear. And dont put it in gear with the kick stand down t may stall on you

hope this helps

Sound like you have reasembled something Incorectly, poss selector fork not located on pin, either way i think you are going to have to strip it again, always good practice to try all the gears on the bench, after asembling the crank cases,you could check the gear shaft is located properly in the. Selector

If shaft and lever is undamaged, more than likely the gear selector shaft spring is misaligned or broken. Place in neutral. Remove pinch bolt from gear lever and remove lever. Undo covers and sprocket for access to selector mechanism.

The link below has exploded view diagrams and part numbers/names for the whole bike in sections.

Gear shifting is 6th from bottom of list.
Goodluck and Cheers.

http://www.motorcycle.mrsuzukiparts.com/2003-RM125.htm