I've just bought a Cota 348 which is in need of some love and tenderness. Most of it has come apart easily as it hadn't been too badly abused in the past. However the drive gear on the left hand side which engages with the clutch outer basket isn't budging.

I have ground the arms of a 3 leg puller to fit and heated it until the metal has started to blue but it hasn't budged even a little bit.

Now I'm begining to think that it isn't on a spline or woodruff key and it may be on a thread (well you never know). Any help or tips will be much appreciated.

In addition is there anything to watch for when I split the cases?

If you search the twinshock or Montesa forums you'll find info on removing these - they are tapered and can be stubborn.

Look out for O rings on the bolts (either side) that hold the crankcases together as this was Montesa's excellent way of making the gearbox and crankcase oil / air tight. Make a note of which bolts have them for reassembly.

There are shims either side of the crankshaft underneath the crank seal carriers

When you split the cases try and leave the gearbox sitting in the R/H side casing (ie: final drive side) There are shims on either end of some shafts and you won't want them rolling around on the bench with gear cogs etc. Also, some cogs slide on needle rollers, not cages but 3 loose rollers, so watch they don't fall out as well as they are different lengths for different cogs.

No thread. Its on a taper and they are typically hard to get off. Make a puller that spreads the load over the whole circumference of the gear and you can really go to town loading it up. Loading+heat+a sharp tap on the end of the puller got mine off

If you search the twinshock or Montesa forums you'll find info on removing these - they are tapered and can be stubborn.

Thanks for the info. I have been searching the web for a couple of days for info on this but can't find any (hence this post). Which forums do you mean specifically as there are so many to chose from. Thanks again