My TY80 Rebuild

[thedktor]

It would appear I didn't post the successful rebuild of our TY80 engine after some problems discovered, so here it is:

Just to recap, a year ago we acquired a TY80 that had a recent rebuild but suffered from a gear-change problem – up changes fine but down changes very unreliable. It also rattled more than I would have expected from a rebuilt engine…

So easy job first and check the clutch mechanism and general condition under the LH case:

All good, so take off the RH case and clutch to check the gear-change mechanism:

Note the fantastic homemade clutch holding tool that came with the bike.

The gear-change mechanism has nothing obviously wrong but I notice the selector drum is free to rotate instead of clicking into place with each gear. Hmm, that’s not right but where is the indent spring thingy??

The other end of the drum, deep inside the engine…. Oh dear, but wait! The indent spring and pin bolt on from the outside of the engine and off it comes easy-peasy!

And the pin had jammed in, so loosened it off, put it back, and the gear change perfect.

So very pleased with that, until……… I look at the clutch primary-drive gear:

A new clutch is £200! But soon find one on ebay for much less. In the meantime I’m checking the engine over and notice the crank is completely out of true on both sides!! And hence the mashed gears…

Engine comes out, and cases split, all quite simple on this little bike.

Crank goes off to get straightened, and declared fit to use, and in the meantime pop in some new main bearings in case the wobbly crank damaged them.

All ready for reassembly:

Note what great condition the innards are in for a 30+ year old bike. Cases back together, no gasket so green Hermetite used – hope it’s the right stuff!

Back in the frame and do up the primary nut:

Kick-start and gear-change mech fitted and tested:

New s/h clutch cleaned up and ready for oiling as it goes on:

Torquing up the clutch nut:

Stator plate goes back on, and it should run better now the point’s cam is running true!

Flywheel, and using my new holding tool

The horrible clutch-release mechanism, which I’m sure was on my Fizzy as well:

Greased up and put back in the magneto cover. Then piston oiled up for fitting:

Ready for the cylinder:

Torque the cylinder/head nuts:

Check for a spark:

Yes, all good so far!

cont....

Edited May 20, 2011 by thedktor

[thedktor]

Strip and check the carb over:

All good, but its so small! Fitted:

Threaded ring attaches the exhaust:

And just one screw supports the whole thing!

Tasty aftermarket footpegs and rear brake lever go back on:

Fill with oil and she fires up, smooth as you like

What a little beauty