“A little” movement in the clutch housing is normal.

To loosen the clutch hub nut I usually put a bike in fifth gear and then put the rear brake stuff back on. Then I get someone to step on the brake, and then loosen the nut. If you are alone, you also can put a stick through the wheel and then rotate the wheel until the stick touches the swing arm… and then loosen the nut.. be very careful though and do not force it, if the nut is really stuck.

Sometimes though I have had to use some airtools…. Sometimes the clutch hub nut is really stuck and you can do damage if you are not extra careful..

Can you find some play in the balance shaft bearings?

I tried to take mine off without the proper tool and it cost me dear :( very easy to smash outer basket,windy gun is best option without clutch holding tool IMO

ahh the 'in gear with the back brake on' scenario.(much easier with a drum brake)
The nut wasn't particuarly tight. but wasn't loose.
http://lh6.ggpht.com/_aJzSBN66Sc0/Sk...0/P4290240.JPG

you say a little movement of clutch basket is OK, it is only a small bit of play and nothing looks worn. there is a slight bit of play from the shaft.

http://lh6.ggpht.com/_aJzSBN66Sc0/Sk...0/P4290245.JPG


http://lh5.ggpht.com/_aJzSBN66Sc0/Sk...0/P4290260.JPG

the idle gear for the kickstart is a very sloppy fit on its shaft, is that normal?
it looks OK though?
http://lh4.ggpht.com/_aJzSBN66Sc0/Sk...0/P4290267.JPG

http://lh3.ggpht.com/_aJzSBN66Sc0/Sk...0/P4290243.JPG

whilst its all open, what should I be checking and how?

cheers for all the help so far

.

...bump........

while you have it stripped down pop the balance shaft and crank timing gears off and check for any woodruff key damage especialy on the crank shaft it will also allow you to inspect the bearings for signs of damage and wear.

Its pretty bad if you can SEE damage on a bearing. You would most likely have heard it.

I remember my kickstart idle gear being a bit sloppy also so I guess it is normal?

Vando :innocent:

with those timing gears in place it would mask some of the normal signs of bearing wear and wont allow to check movement as the gears being meshed together would restrict the ability to check movement/play properly.

the posted problem is vibration so "noise" would not have been so obvious plus pitting. over heating and other damage to the bearing and its housing may not show as noises but mis alignment would give bad vibes.

i have worked on large electric motors and generators where bearings run quiet but vibrate like hell when the housings wear the xt has cast iron bearing housings cast into the alloy crank cases so should not suffer from mis alignment the main reason i said to visually inspect was to look at the woodruff key as mine sheared off ruining the engine not to visually inspect the bearings.

my two pence worth.it's a pain i know but i'd pull it apart and have a look.
you mentioned it had done at least 54000 miles, thats a fair bit, and then it's had a top end overhaul.
so you've got a nice full compresion top end running on a 54000 mile bottom end, not really surprising it vibrates!

gear wheels off and the keys are OK.

I saw this and thought they were cracks, but just imperfections in casting I think?
http://lh3.ggpht.com/_aJzSBN66Sc0/Sk...mera%20233.JPG

http://lh5.ggpht.com/_aJzSBN66Sc0/Sk...mera%20235.JPG

bearing on the balance shaft has neglible play, but on the crank there is a bit of play. the movement isn't the bearing, it is clearance between the crank and the inner race, is that normal? you can see the gap with the difference in these two pics
http://lh4.ggpht.com/_aJzSBN66Sc0/Sk...mera%20237.JPG

http://lh6.ggpht.com/_aJzSBN66Sc0/Sk...mera%20238.JPG


cheers

yeh those casting marks are pretty normal but the inner race should be a snug fit on the crank if it has too much play the crank can rotate in the inner race wearing the crank shaft after all thats what the bearings are for, any play/ movement will be exaggerated the faster the motor spins how much movement is there can you make it rattle?

i can get it to just about do an audible knock knock, and the bearing race spins freely on the crank, :(

thats not sounding to good i'm afraid it looks like it needs to have a bit more overhaul work :( hopefully just needs the bearings replacing.

Oh dear. I'd agree with Wolfzero.
If you can rotate the inner race on the shaft of the crank, that's bad, and is pretty certainly the cause of the vibration.

These two items should be an interference fit.

It's possible, if not highly likely, that the bearing has seized at some point, forcing the crankshaft to rotate inside the inner race. This will seriously damage either the inner surface of the inner race (repairable with a new bearing), or more seriously the outer surface of the crankshaft.

Depending what repair facilities/workshops you have access to, that might be repairable by metal-spraying the crankshaft and grinding to the correct diameter, or, exceptionally and maybe temporarily, finding a bearing with slightly smaller inside diameter and grinding the crankshaft to be an interference fit.
Either way, that bearing will certainly need repacing.

But returning to how you described the vibration, (it seemed pretty awful) other damage could have been done.
For instance, the outer race should be an interference fit in the crankcase, but may no longer be so. That will need fixing.
And in the extreme, the whole crank should be inspected carefully incase there is other unseen damage.

These engines seem to have a reputation for being pretty strong, so I hope it isn't as bad as this, but it could be.

If the new bearing isn't an interference fit on the crank, a cheap fix is to do multiple (50 or more)small (depending on the clearance) dot punch indentations around the crank to give a knurled effect, therefore creating an interference fit between crank & bearing inner race. And possibly some loctite during assembly for insurance. I'm not sure if these cranks are nitrided, if so this may not be possible due to the hardness of the crank.
Bob