1996 RM 250 gearbox problems

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#1
1992 RM 250 gearbox problems & parts interchangability

Looking at picking up an 92 RM250 off a mate to fix as a buddy bike. It has terminal gearbox issues (allegedly) no idea what is wrong in their exactly, but I think its stuck in gear. Im looking to either replace the shot parts in the gearbox, or replace the whole motor/bottom end with a second hand one. My question is.....Are gearbox issues normal in RM's? Is this one of those probs that is common to that year model?

Sorry for vague prob description, ill post with more detail when/if I pick up the bike. Any help is appreciated.
 
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#3
Just picked it up, its a 92 not a 96 as I first thought. Shifting wasnt the issue, but getting past second gear was. I havent had time to pull it apart yet but apparantly the shop he had it at confirmed there is something broken in there.

I am thinking that sourcing a second hand bottom end is going to be way easier than playing gearboxes. Does anyone know if I could use the bottom end off any other year models or will it have to be a 92?
 
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#4
Update.

Well, I checked the serial number and its actually a 94 model. It has a 96 jug on it though. Not sure where 92 came from. Anyway, the pervious owner went for a ride without any transmission oil (unbeknownst to him) and the bike lasted 2 hours before the box seized. My Clymer manual is due to arrive today, will be splitting the case tonight and rebuilding the box in due course.

My question is how to go about this. My local parts shop mentioned using a rubber mallet, another source said to use or make a crank splitting tool. Can anyone who has split a case give me a tip here? Whats the best way of splitting a case?
 
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#6
make 1 motion pro is too expencive-
try a stearing gear puller - rubber mallets work ok too-
problem is if its seized from no oil it might be harder to get apart-
if you have a cool local shop- they might split it for you for 20 or so -- be done with it - wile you wait
compaired to 140-180 for a crappy tool!
 
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#7
Got the case apart. It was an absolute piece of cake, came apart virtually by hand with a few taps on the crank shaft and gearbox shafts with the rubber mallet. The problem is that the shift forks are completely stuffed. The lobes on the ends of them have been worn/burnt off completely hence the shifting issues. Also, the two right side bearings, the ones on the end of the input and output shafts, are pretty average. Im going to replace them. It is interesting to know that these forks are the weakest link in the package when it comes to riding the bike without any tranny oil....the heat built up burnt the lobes right off. I am happy to post some photos of them if people think it will be useful.

This job really isnt that hard at all, anyone who is considering splitting the case to do gearbox work or replace bearings should go ahead and do it. The shops charge like a wounded bull for this work, you could save serious money.