I've not posted for a long time, but thought I'd provide an update on one of the two Teneres that we bought for a RTW trip in 2009.

My Tenere is fine, and still going strong at 50k miles - with just standard oil and filter changes, and valve check at about 35k miles .

My SWMBO's Tenere on the other hand has not.

At 45k miles we went on a tour of Scandinavia - upto NordKapp and back - a trip of 4.5k miles.
About 2k miles it started with an unhealthy rattle - much umming and erring, and listening to then engine with the clutch engaged and disengaged, and no one could work out if it was top-end, bottom-end, gearbox, or what.
At a campsite we pulled off the camchain cover - all ok. Removed the clutch - all ok. Removed the alternator cover - all ok.
With little option - we continued. It didn't burn any more oil, there was no loss of power. It just rattled so badly that children in the streets were running for cover ;-)
After another 1000 miles or so, we took it into a Yamaha dealer, who was also stumped - his only recomendation was to put it in a crate and send it home ! We carried on.

Back in Blighty, after 2500 very loud and rattly miles, we were in a position to have a more detailed look. I removed the engine ready for dismantling. Removed the clutch side and primary drive, and discovered the primary drive nut was loose (tab washer still in place). On removing this, the cause of the noise was discovered - a badly worn main bearing. The crankshaft can be rattled within the main bearing - it's so bad you can almost get a finger nail between the crank and the inner race of the main bearing !!!
A new crank is approx �300, and with labour (I don't fancy stripping the topend, and splitting the crankcases), and other parts, fear the bill will be �1000.

All credit to the Tenere for keeping running for all those miles with such severe damage !!

So, what options do I have available to me:
1) Shell out �1000 repair for a bike that is probably worth �2k
2) Break the bike and hope I can get �1000 for the various parts
3) Source a used XT660 engine - but these are fetching �700 odd at the moment.
I'm erring towards option 2.
Ebay here we come...

Not good news, we have seen a few main bearing on the Z motors.

It would be far cheaper to split the motor replace the main bearings.

There is an engine build going on behind the sceens here in Brisbane which might interest you but I can say much until it is running.

__________________
Click here to join the XT Supporter's scheme

Mods that I have done to my XTX's

My 04 XTX
Stage 1 & 2 DNA filters / Kev fuel mod / snorkel mod / Drilled air box mod / Engine breather mod / Fork Spacer mod / 15w fork oil /
[
My 07 XTX
Raptor 700 cylinder 102mm / Modified Crank Case to take a 105mm Raptor Cylinder / 11:1 102mm JE Raptor piston / Stage 1 Raptor Hot Cam / Ported head / Colder Spark Plug / +2mm Throttle body / DNA stage 1 & 2 filters / Modified Air Box / Snorkel removed / Worry Brothers stage 2 filter cover / 6mm & 8mm Bolts Replaced with Titanium Bolts / Recovered seat in Black / O2 Eliminator /

My 09 XTX
59HP at the rear wheel / Stage 2 Raptor Hot Cam / DNA stage 3 Air Box / Carbon Can Exhausts / Modified Exhaust Link Pipes / PCIII With Custom Fuel Map / Wideband Commander O2 Data logger / LCD100 Dyno Jet display & fuel adjuster / 2500 OHM HT lead instead of a 10K OHM XT lead / Extra Coolant Cooler / Protaper Fat Bars / Tail Tidy With LED Tail Light / OKE Protection Knobs / LED indicators / AIS blocked / Modified rear sprocket rubbers / Rear Foot Pegs removed / 09 ECU With 02 Sensor Changed To A 06 ECU / Complete wiring harnes Changed from 09 to 04 / Home made LED resistor flasher / Hole drilled in the fuel tank filler neck to allow quicker filling / Modified Bar End Weights / Progressive front fork springs, 15W fork oil, forks lowered 25mm, used XTR rear links lowering the rear 20mm, rear spring one click stiffer / Changed front & rear guards from blue to black / 47T rear sprocket / Speedo Healer V4.0 / Kev throttle cam mod / Throttle grip mod / The new 2010 O2 sensor mod is out, works a treat, The new 2012 O2 Controller is out, PM me for details

Now ride a 2018 MT09SP ABS + TCS

My KTM 990 SMR Mod book. http://www.ktmsmt.com/viewtopic.php?f=13&t=4946

What was the weight, brand of engine oil and service intervals. As Kev said it would be better to split and replace as a second hand engine you do not really know what you are getting.

it worries me how often this seems to be happening. I love my ten and see it as a long term bike to cherish but I dont want a bike that goes bang just when you dont need it too.

Intrestingly Yamaha techs have been singing the praises of the Super ten but i belive that was built in Japan.

are all the 660 engines built in Italy ?

is this just a problem on the Z ?

is there anything you can do to prevent the problem ?

__________________
Ride On :tenere:Camel 2008XT660Z
harvey mushman did it in the dirt Uma 1994 TT250R

Run the best oil you can afford and do 5000km oil changes at a minimum. I believe leaving the oil in for 10000km especially a mineral oil is a bit to much for the oil.
I also believe if a main bearing was faulty it would fail in the first 1000km not after 50000km. Another thing that could cause main bearings to fail over time is a out of balance crank.

Could it be that the cause lies in a loose nut, the one that holds the balancer on the crank in place... seems to happen once in a while...

... which might have result in a worn out crankshaft bearing after so many miles unbanlanced operation...??

... just speculating...

but check this topic: http://www.xt660.com/showpost.php?p=141935&postcount=15 also at about 50.000km.

This is what it sounded like: http://youtu.be/rjYYt1DstIU

EDIT: on a second read of TS first post I noticed: and discovered the primary drive nut was loose (tab washer still in place) ... so yes ... it seems to be the same cause...

Niek (the one of the videoclip) decided not to ride with the bike and had the dealer fix it. All done and his bike has ridden another 50.000km's since...

HJ

__________________
Riding the Mad Mule !! ... no more... went orange...

Sorry to hear of you troubles russolivant.

@singleminded: Assuming the nut was tightened correctly in the first place it would not come undone because it is locked by the tab washer.
The only way for the nut to become loose is for something to be wearing due to friction. In my unfortunate experience ( http://www.xt660.com/showthread.php?t=18016) it would appear to be the plate washer between the main bearing and the drive gear.

It also appears to me that the clearance between the main bearing and crank on the primary drive side allows the slipping of the crank in the inner race. Is this what then causes wear on the plate washer/face of inner race? and hence a loose nut which causes the crank to slip even more in the inner race which causes more wear on the plate washer.....................

If you're lucky russolivent you may get away (for awhile at least) with just fitting a new bearing.

BTW, and signs of brown slime/corrosion on the primary drive side of the crank/gear assembly?

It would be useful for "statistics" if you (or your dealer) could let Yamaha know of your problem (including chassis & engine numbers). I think they got bored of hearing from me.

Best of luck and please keep us posted...........