[madebypedro]

Hi there

My name is Pedro and I'm from Portugal. I've just bought my very first motorcycle - a 1971 CB250 K3 - for a reasonably cheap price, but with all things cheap, it's got issues.



The bike starts and runs quite well, but it doesn't drive: I can't use the clutch to change gears. When I squeeze the lever and the cable is pulled, the mechanism inside (parts 6-10 on the diagram) pushes the sprocket cover outwards, not activating the clutch. This happens because there are two screws missing from the bottom on the cover (#16 on the diagram).

Attachment 195994

Upon close inspection, I now realize that the previous owner welded the shifter joint directly to the spindle (!!) and now I can't take the cover off to see what's wrong apart from the missing screws.



Does anyone have any advice on how to approach this without killing the spindle?

Thank you!

 

[FrankyV]

Hi there

My name is Pedro and I'm from Portugal. I've just bought my very first motorcycle - a 1971 CB250 K3 - for a reasonably cheap price, but with all things cheap, it's got issues.



The bike starts and runs quite well, but it doesn't drive: I can't use the clutch to change gears. When I squeeze the lever and the cable is pulled, the mechanism inside (parts 6-10 on the diagram) pushes the sprocket cover outwards, not activating the clutch. This happens because there are two screws missing from the bottom on the cover (#16 on the diagram).

Attachment 195994

Upon close inspection, I now realize that the previous owner welded the shifter joint directly to the spindle (!!) and now I can't take the cover off to see what's wrong apart from the missing screws.



Does anyone have any advice on how to approach this without killing the spindle?

Thank you!

My guess is they welded the shifter because the shaft is stripped. You can grind off the weld to remove the shifter or just replace the missing cover bolts and see if that solves the problem.

 

[madebypedro]

Franky, that's my guess too. The thing is that there's still a piece of the screw on the left and on the right, the thread/stub has broken off the engine half. Need to weld it and tap it again.

 

[Gixxer-18]

You'll have to grind off the weld to remove the gear linkage any way and then you will have to replace the gear selector shaft and oil seal. Then the sprocket cover can come off and you can then check the lifter mechanism and hopefully you can get at the two M6 screws that have broken off. If there isn't enough metal left of the screws to grip you can carefully mig weld a blob of weld onto the screw shaft. The heat will also help free the screws. The weld won't stick to the Ally of the cases. Then you'll need to grind clean or cut off the end of the change shaft and pull it out the gearbox from the right side of the engine you'll need to start looking for one on EBay or somewhere.
Make sure it's straight and the splines are clean. You'll also need a new linkage and possibly the gearbox oil seal too.
Good luck and welcome to the forum
Nigel.

 

[madebypedro]

You'll have to grind off the weld to remove the gear linkage any way and then you will have to replace the gear selector shaft and oil seal. Then the sprocket cover can come off and you can then check the lifter mechanism and hopefully you can get at the two M6 screws that have broken off. If there isn't enough metal left of the screws to grip you can carefully mig weld a blob of weld onto the screw shaft. The heat will also help free the screws. The weld won't stick to the Ally of the cases. Then you'll need to grind clean or cut off the end of the change shaft and pull it out the gearbox from the right side of the engine you'll need to start looking for one on EBay or somewhere.
Make sure it's straight and the splines are clean. You'll also need a new linkage and possibly the gearbox oil seal too.
Good luck and welcome to the forum
Nigel.

Thank you very much! It's good to be here and learn.