Ty250a stemhead bearings.

[typarts-aus]

I recently bought a tapered needle roller bearing and seal kit for my 74 ty250 but whilst the diameter is correct, the top bearing protrudes an extra 7mm and this prevents the top locking nut from fitting. Has anyone else tried these kits and if so did they fit. The company I bought them from has been helpfull but is baffled by the issue. Any advice would be appreciated.
Greg

[FM350]

I would guess the bearing kit you have is for later bikes, which are probably different to your 250A?

[David Lahey]

I recently bought a tapered needle roller bearing and seal kit for my 74 ty250 but whilst the diameter is correct, the top bearing protrudes an extra 7mm and this prevents the top locking nut from fitting. Has anyone else tried these kits and if so did they fit. The company I bought them from has been helpfull but is baffled by the issue. Any advice would be appreciated.
Greg

That same thing happened to someone else on these forums who bought a new TY twinshock head bearing kit. I remember measuring a set of mine to confirm for that person what the correct size should have been. I hope it's not the same supplier still selling the wrong size bearings.

[typarts-aus]

The crowd I bought mine from have the name of an Egyption monument and are UK and NZ based. Are tapered needle roller bearing replacements available to fit my 74 and if so what are the sizes as I nnow cannot see that being an option given the thickness required.

[FM350]

I would guess that unless you have some way of machining your head stock, taper bearings intended for later bikes arent going to fit. Cup and cone head bearings are just as good as tapers though, so if yours are in good condition just refit them, and tap the headstock for a grease nipple, and keep them lubed.

[David Lahey]

The crowd I bought mine from have the name of an Egyption monument and are UK and NZ based. Are tapered needle roller bearing replacements available to fit my 74 and if so what are the sizes as I nnow cannot see that being an option given the thickness required.

Yes I think that was the same brand as the other person had problems with. The correct bearings are available for the TY250A, and as far as I know they are the same size as the bearings for all the Twinshock TY250 and TY175 models and dozens of other Yamaha models of that era. I have bought 6 or 7 sets of aftermarket tapered roller steering head bearings for TY250 and TY175 over the past 10 years and all have fitted perfectly. I will do some measuring tomorrow in the shed and post up the sizes.

[David Lahey]

Just went to the shed and found:
Top bearing should be 25x43x11
Bottom should be 30x48x13

[FM350]

You are quite right David............tapers are available from here: http://www.allballsracing.com/22-1008.html and seem to fit a very wide range of different bikes.

[typarts-aus]

Hi Guys, I have posted a photo of the top bearing installed and for my money it sits too proud. I checked the numbers on the bearings and they all stack up as per Davids measurements. I will go through and check the installation of the bottom bearing but I am sure I have that seated properly.

[typarts-aus]

OK, 3rd time lucky. I used the original seal cleaned and reseated the bearings and managed to get about 5mm of thread for the adjuster nut. It's not what I'd like but there's plenty of engagement for the thread. Good chatting with you chaps and thanks for the advice.