Vintage Dirt Bike Q & A

Hi guys,
I have just been given an MT125 Elsinore which has been in storage for a long long while.
I have managed to get the motor running and it engages first gear with some difficulty and one of the other gears (second it feels like) with even more difficulty, but I can't engage the other gears.
I have changed the gearbox oil and this has not helped.
The clutch seems to be working ok with no snatch or slip.
Before I take a deep breath and dismantle the gearbox to have a look, has anyone any suggestions?

Ray

Does the shift lever return to center properly and does it still have the original gasket on the clutch cover?

The shift mech was shimmed to eliminate any end play and if the clutch cover has a thin replacement gasket, it can bind.

first it would be nice to know why it was put in storeage, was it for this problem? if not then it shouldn't now. second i wonder how clean or dirty the trans oil was when put away. cause the dirty oil could have gummed up after all these years. with wear and tear and clutch fibers and age you can make a good resin, that could be staining the shafts and forks and stuff. i would try to see in the filler hole to see if there is a tide line going across the primary to the clutch. yes or no then move on. you could remove the cover and see all the sh8t at the bottom that's causing this. or try to flush it out with lighter oil and some use or flush it with a good solvent. i would do anything not to do another motor.

Thanks to Ricortes and Charlie for for your responses ,

Further checks showed that I was engaging 1st and 5th gear and none of the others (not 1st and 2nd as I first thought).
The sequencing drum was turning when the shift mechanism was operated, so I suspected that someone had tried to do some work on the gearbox and had left a part out or had inserted a part incorrectly.
A strip down showed that the shifter forks are as new, the interior of the gearbox is clean and the engine looks like it has had a decoke so at first glance I suspect it to be an incorrectly assembled gearbox.
There's nothing obviously wrong and the gears look healthy so I'll get a gasket set, clean everything up and re-assemble the gearbox and engine.

I guess whoever did the work got frustrated at a poor result for all their work and just stuck the bike at the back of the shed.

I'll keep you posted on the results of my efforts.

Ray

I stripped the gearbox and inspected all the components which all looked ok except the gearchange drum which had a hairline crack at the selector quadrant end, so I replace this part.
Everything looked to be assembled correctly when I dismantled the gearbox, so when I re-assembled everything I focussed on setting up the selector quadrant and main gearchange shaft correctly.
This looks like the problem area as I could duplicate the original fault, by incorrect assembly of these components.
Everything works fine now and when I had the beast apart I changed all the bearings and seals for good measure.
The bike started second kick and we are heading off to the local MX park to give the bike a workout.
The bike looks "ratty" and needs some serious attention because of years of abuse and decay, but I was also given a heap of parts including a dismantled CR 125 frame, forks and part of an engine/gearbox so I'll start to rebuild the spare frame and perhaps end up with a CR 125.

FWIW: One of the spare/replacement engines I got for my MT250 had a similar problem with incorrect assembly. I wasn't quite so lucky as one of the selector forks just about melted from friction. Only thing I can assume is the previous owner ran the hell out of it in 1st gear until they finally broke the rest of the bike.