Cota 248, 1981

[dr nosh]

Now at the stage of getting the engine back together, after a bit of a long rebuild.

 

Anyway, there is a breather at the rear of the motor, from the top of the gearbox, and also a breather in the magneto cover.

 

Are these actually necessary?

Is it a good idea to remove them?

 

If they should remain in place, should I;

Gearbox - Run this up into the bottom of the air filter box?

Magneto - Run this up the frame to under the tank with a 1 way breather on it?

 

Advice appreciated. Thanks.

[section swept]

Don’t remove these breathers from the bike. Make sure the pipes are good and flexible, not perished or clogged inside. Make sure that where the pipes attach to the cases that the holes are clear. Route the pipes where they cannot let water in but allow moisture out. Your  suggested routing sounds good but I doubt you will need a one way valve, possibly a ‘U’ bend in the breather pipe behind the tank to delay water entry if you drop the bike in deep is water. Clear pipes a good idea as you can see what’s gong on! Fitting the gearbox breather into the air box is not a bad idea either.

Is there a breather on the clutch case? 

[dr nosh]

Thanks.

There is no separate breather on the clutch case. I think this vents through the gearbox.

Good point on using clear tubing. (The gearbox tube and threaded coupling is actually blocked solid with gunge!!).

Another question.

The final drive sprocket is a push fit onto the g/box output shaft, and this is then followed by a 'sprung loaded cup' over an O ring on the shaft itself. In order to keep these on the shaft there must be a circlip or something that then fits into a groove on the outer end of the shaft. I can't make out what this is actually supposed to be or look like from the illustration in the parts book. p/n 6763.165.

[section swept]

10 hours ago, dr nosh said:

Thanks.

There is no separate breather on the clutch case. I think this vents through the gearbox.

Good point on using clear tubing. (The gearbox tube and threaded coupling is actually blocked solid with gunge!!).

Another question.

The final drive sprocket is a push fit onto the g/box output shaft, and this is then followed by a 'sprung loaded cup' over an O ring on the shaft itself. In order to keep these on the shaft there must be a circlip or something that then fits into a groove on the outer end of the shaft. I can't make out what this is actually supposed to be or look like from the illustration in the parts book. p/n 6763.165.

That probably isn’t correct, if the clutch vents through the gearbox you will have oil being sploshed into the gearbox or vice versa! Their cunning these manufacturers even to the point of relying on a tiny hidden hole to do the venting. Sprocket held in place by circlip.

[potto]

On ‎4‎/‎2‎/‎2018 at 12:03 AM, dr nosh said:

Thanks.

There is no separate breather on the clutch case. I think this vents through the gearbox.

Good point on using clear tubing. (The gearbox tube and threaded coupling is actually blocked solid with gunge!!).

Another question.

The final drive sprocket is a push fit onto the g/box output shaft, and this is then followed by a 'sprung loaded cup' over an O ring on the shaft itself. In order to keep these on the shaft there must be a circlip or something that then fits into a groove on the outer end of the shaft. I can't make out what this is actually supposed to be or look like from the illustration in the parts book. p/n 6763.165.

Its more of a "C'' clip and just slips into the groove in the output shaft,the spring loaded retainer holds from passing over the shaft when in place.

[dr nosh]

C clip sorted.

 

Just finished sorting the gear change mechanism. Very notchy.

The pawls were all good, but the plate that they slide across had a groove worn in it and a burr.

Stoned off the burr, and ground a small rad on the leading edge of the lower face of each pawl, so the pawl now slides across without the leading edge catching.

Re-assembled and now much smoother.

Next. Fit engine to frame.

 

[dr nosh]

Now about the eccentric adjuster. When this is assembled over the M6 stud, the adjustment made,  and the locking nut is tightened up, there is still movement in the adjuster plate.

Should the adjuster plate be locked tight in position?

If so, then the back of the eccentric adjuster is proud by 0.2mm preventing it being locked tight.

Is this correct, or have I got to machine this so its 'sub-flush' therefore allowing the adjuster plate to be locked preventing movement?

Thanks

[potto]

On ‎4‎/‎8‎/‎2018 at 8:35 AM, dr nosh said:

C clip sorted.

 

Just finished sorting the gear change mechanism. Very notchy.

The pawls were all good, but the plate that they slide across had a groove worn in it and a burr.

Stoned off the burr, and ground a small rad on the leading edge of the lower face of each pawl, so the pawl now slides across without the leading edge catching.

Re-assembled and now much smoother.

Next. Fit engine to frame.

 

Wow nice job on the side cover,however mine had been welded and not really that top notch,your work is great cheers.

[dr nosh]

Oh. Welding magnesium....not easy.

I was lucky, noting cracked or broken on the engine, which is more than I can say for the state of the frame and cycle parts.

 

Anyway, back to the question about the gearchange eccentric adjuster. Should this lock the plate in position?

Anybody got any views on this?