Vintage Dirt Bike Q & A

hi everyone i recently picked up a mt250 and it ran for awhile like 1 month then when i was riding my chain sliped off the back sprocket and now i dont have 2nd gear when i shift it simply slides into neutral. but i can get it passed 2nd by pinning the gass and shifting hard. anyway now the engine is off the bike and i'm looking into what happed i have not split the case. to tell ya the truth i dont know how i have some of the outside parts off such as the shifter and the kickstart but i cant get any futher

i need to know if i truly need to split the case and if i do do i need to pull the fly weel and do i need to take off the berring retainers becaused the bolts are staked in. and last what happed i really dont know what went on after my chain slipped off. thanks

big greg

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74 mt250 elsinore

You will probaby have to spend $20 or $30 for a manual to get it back together if you split the cases. The transmisson just kind of falls apart as you take it out. I have seen illustrations of people putting all the gears and spacers on a wire as they dismantle it to keep it in order. I have never been that lucky where everything stays nicely in place when you split the cases.

With just the clutch cover off, right side cover, I would check the ratchet/detent system before I split the cases. It has a long plate with a couple of teeth coming off that engage the shift mechanism that rotates a drum with notches in it. There are spring loaded rollers that fit into little half moons cut out of the drum to lock the selected gear. The plate is kind of cheap and bends easily. In any event, make sure the shift returns to center! The ratcheting action doesn't work if the shifter doesn't return to center.

If the drum is spinning and indexing properly you may have broken the 'dogs' off the gear. This doesn't sound likely to me as your WOT method wouldn't work if that had happened. Usually worn dogs mean it pops out of gear but shifts normally.

Splitting the cases if pretty major. To give you some idea of costs, head bolts alone will cost about $20 each from a dealership if you go that route.