83 yz 125. Split cases to find shifting problem. Can't see anything wrong. No broken gears, forks look okay. Can anyone give me tips on the next step?

Yes, the case will need to be split. The problem is likely to be a bent shift fork. A bent fork can stop the dogs on the slider gear from fully engaging in a gear. If the problem turns out to be a stripped gear, you need to replace BOTH the stripped gear AND the gear the bad gear meshes with.

2nd gear is at the bottom of the shafts if the tranny is stacked in the mag side case. So it is controlled by the bottom fork. You should be able to shift it thru all the gears by turning the shift drum. Make sure as you shift the shafts stay all the way in the output shaft and idler shaft bearings. As you shift it, look for full mesh between the wheels(shaft that goes to the clutch) and the gears across on the output shaft.
If that all looks good, the shifter cluster(on the end of the shift drum, with the 2 dogs that engage the notched wheel on the end of the drum) may not be lined up properly. If the gears and shift drum are new, I'm thinking I'd look there first. Good luck!

It could be your shift fork or you have a few broken teeth in 2nd gear unfortunately you will need to split case to see what is wrong.

I’m happy to assist further over the phone at https://www.6ya.com/expert/michael_18b4936ebf017b21

im having the same problem with my 2003 rm 125, tombones49 is wright about the shift forks.

You probably have a bent shift fork or two > very common and expensive. The only other possibility is the shift linkage behind the clutch is messed up in some way > cheap but seldom ever happens.
If it is the forks, then the entire engine comes out of the frame and gets completely torn down. The top end comes off, the case covers come off, the clutch, shift shaft, kick starter, flywheel and electrics all come off. Then the case is split to gain access to the gears and shift drum. The gears and shift drum now get removed and now the forks can be replaced. A few special tools are needed. Sorry for having to give you the bad news.

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You have a bent shift fork. The repair means taking the engine out of the frame then removing the top end, removing the flywheel and electrics, removing the clutch , shift mechanism and kick starter and a few other parts. THEN you are ready to split the gearbox to remove the gears and crankshaft and then the shift drum and bent shift fork. Next you get to put it all back together. This is a pretty big job for the home mechanic.

You will need an impact driver, flywheel puller, case splitter and torque wrench plus the normal screwdriver, pliers, etc.. Alternate to the special tools is taking it to the dealer and say "Fix it".
I normally tell people to take it to the shop just so they don't get into such an involved project.

Free service manual PDF download at > http://www.carlsalter.com/motorcycle-manuals.asp

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You have a bent shift fork. The repair means taking the engine out of the frame then removing the top end, removing the flywheel and electrics, removing the clutch , shift mechanism and kick starter and a few other parts. THEN you are ready to split the gearbox to remove the crankshaft and then the bent shift fork. Next you get to put it all back together. This is a pretty big job for the home mechanic.

You will need an impact driver, flywheel puller, case splitter and torque wrench plus the normal screwdriver, pliers, etc.. Alternate to the special tools is taking it to the dealer and say "Fix it".
I normally tell people to take it to the shop just so they don't get into such an involved project.

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Okay hotcrap10, since the fellow who did the original posting is not responding to clairification requests, I hereby turn this posting over to you. ( sounds official don't it! ).

Here are the possibilities > > Bent clutch push rod, missing push rod ball bearing or push rod, worn out actuator shaft cam, Missing friction disk (5), or pressure plate (4), totally worn out friction disks, clutch plates not installed in the correct sequence, extremely weak clutch springs, stripped teeth on the clutch hub, wrong clutch cable length (inner cable vs outer cable), broken shaft, bent then broken shift fork stems, broken slider gear dogs and a missing shift fork pin.

You didn't say if anyone had worked on the clutch or gearbox so I am throwing in nearly EVERYTHING possible that could create the problem. A little more background and most of the above can be ruled out. What kind of oil do you have in the gearbox? Did you take the clutch apart? What else can you tell me? Get back to me.

• Obviously a Kawasaki dealer can replace the broken shaft. I assume you want to replace it yourself. I do not recommend you replace it yourself but if you feel able then > > >
• Drain the gearbox and pull the engine from the bike. Remove the left case cover.
• Remove the right side case cover. Remove the clutch.
• Disengage the shift shaft pawl from the shift drum pins and pin retainer. See if the bad shift shaft will slide out from the center casings. I say " IF " because the shaft may be bent and may not slide freely through the casings. DO NOT try to hammer the shaft through the casings. You will scar the bore at the least and crack or break the casing at the worst.
• If the shaft will not slide out freely, then you will need to cut the shaft in half from the clutch side and remove it from the flywheel side. A Dremel tool will cut the shaft.
• Now install the new shift shaft and check to be sure the gears all shift smoothly up an down, ( rotate the clutch shaft while shifting ). A bent shift fork is a PROBABILITY anytime a shift shaft is damaged as yours was.
• If you can run through the gears okay then re-assemble the engine. Add fresh oil to the gearbox and go for a test ride down the street. If the bike does not shift smoothly then you missed a bent shift fork in the prior step and will need to tear the engine down, split the certer case and then replace the bent fork.
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Well. I'm a motorcycle mechanic and my 2004 RMZ 250 recently did the same thing, The Shift forks inside my transmission actually bent and were not moving the gears as far as they needed to go and eventually got to where it quit shifting all together, recently also repaired a CR 125 That wouldn't shift at all and it was the shaft the shift forks go on was bent and hung the shift forks. Sounds like your shift forks are bent to me though.