Hi all. I'm in Western Sumatra and the dreaded xt660 engine knock has struck. Sounds like this (not my bike in the video): xt660 crank knock 2: http://youtu.be/bEggxJ-EBVg

So, I'm across the whole primary drive nut getting loose thing. Of anyone can point me towards a comprehensive thread that deals with this I'd be mighty appreciative. SPECIFICALLY I'D LIKE TO KNOW THE SIZE OF THE PRIMARY GEAR DRIVE NUT, I don't have a lot of tools (22mm is my biggest socket) or a fantastic work space, so of like to know I'm sorted before i pull the crank case cover off.

I'm working on the advice if of my bike mechanic mate who says:

" I'll start with the good news, it doesn't sound like main (crank) bearings. They give more of a hollow/consistent type knock, rather than your heavy, 1 revolution type knock that you have there. If that makes sense! (Disclaimer: I have been wrong before. Not often, but it happens! Haha). I did a quick google search for tenere noises. Couple of people suggested primary drive crank nut, behind the clutch cover. (The nut holding the gear that drives your gearbox, on the end of the crank) But since it's a lot easier I'd start with the flywheel side. The end of the crank on the flywheel side is tapered & the flywheel is located with a woodruff key. Easiest check will be to open the flywheel nut inspection bung in the centre of the left cover & get a socket into it. 1st gear, rear brake on. If it's loose, there's a chance it's worn the woodruff key/key-way meaning it may happen again. Fingers crossed that's all it is. Then, before removing side covers, I'd get a long screwdriver & use it like a stethoscope. Put the handle end hard in your ear, & place the tip in various locations till you find the loudest source of your noise. That will narrow down left or right at least. Place it on the covers, the bolts that hold the covers on, starter motor, water pump, etc. If you place it half way up the cylinder or the head & it gets louder, well..."

I've tried opening up the port on the LHS of the crank case and tightening the crank nut, but it was already tight and no progress was made. I've tried the screwdriver stethoscope and it's loudest behind and above the oil filter where the crank case and cylinder meet.

Once again, if anyone can link me to a comprehensive thread or can at least tell me the nut size, it could save me having to truck my bike 600km and then ship to Malaysia where i can find a serious mechanic

Cheers
Ro

Have you read this thread?

http://www.xt660.com/showthread.php?t=19747

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Nope, haven't seen it, but frankly it's not much help. I'm in western Sumatra, so i can't just pop down to the dealer for warranty. I'm going to pop off the RHS crank cover tomorrow to see if it is the primary drive gear nut and to see if i can't tighten it enough to get me out of Indonesia and into Malaysia where this bike is more common. I was just hoping to find a thread with some technical know-how and considerations when tackling this job.

Ir's somewhat intimidating when trying this ina foreign country with no hope of support or rescue!

http://www.xt660.com/showthread.php?t=19297

I think this topic will help you out ;-)

Doh! Sorry, the thread I meant to link to was the one that Arjen posted a link to!

19297 or 19747, all just numbers!

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I think the primary drive nut size is 36mm.

Now I'm not at work, or on my phone, I might be able to get my links right!

I think this thread will be useful to you:

http://www.xt660.com/showthread.php?t=20512 (Posted by the same chap who made the video you saw.)

The socket required is 37mm (according to the above thread).

It is also worth noting that the problem with crank nuts coming loose appears to be down to Yamaha specifying a torque setting on the low side. Service manuals quoted 80Nm for the nut, but dealers who have rectified this issue have been torquing the nut to 110/120Nm.

I reckon you'll get away with tightening it to 110Nm and reusing the tab washer (assuming there's nothing else amiss).

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Awesome, thanks for the info. Now to try find a 37mm socket! I also don't have a torque wrench, but i remember torqueing my axle to 110 and then doing it with my short breaker ar I carry witb me and 110 is about the upper limit of what the bar is capable of. Should be enough to get me to malaysia where I'll have to have the side back off again to install a new gasket, so I'll do it properly then. Fingers crossed! I'll update with progress

Evening Gents

You'll be pleased to know that thanks to you I think I sorted the issue out and I'm about to explain how (for future references of n00bs like me). I'm no mechanic and I'm writing for others like me who are asked by fate and destiny to step up and be a hero when this happens unexpectedly on the road, so I'll go into some detail. If I miss anything please let me know.

Sorry for the lack of photos, the internet isn't much chop for uploads here. I'll try to use the correct names from the parts manual, but sometimes the words doohickey and thingamajig might worm their way into my lexicon.

Some tips to begin:

- Make sure you have a clean surface! Chances are you'll spill the odd drop of oil, so it's probably an idea to throw some plastic sheeting down.
- Get rid of those allen keys and use allen sockets like a real adult!Pre-purchase Seriously, they make life so much easier
- The size of the loose nut is a 36mm!
- Pre-purchase a new side cover gasket (Part # 5VK�E5462�10) and clutch cover gasket (5VK�E5453�10) if you can wait. Might also pay to replace the tab washer (90215�20X00) and the other washer too (90209�20012)
- Take lots of photos!
- Take your time! Put some relaxing music on, grab a beer and enjoy the fact you're getting to know your bike better. Think about what you're doing before you do anything!

1) First thing's first, clean your bike! you don't want sand and grit inside your engine, so clean and dry that sucka! While you're here, put it in 5th gear before you switch it off, this will come in handy later.

2) Next remove your bashplate, your 2 RHS plastic farings (radiator cover and air scoop) and drain your oil. I'm sure that it can be done by lying the bike on it's side to conserve the oil, but if you have the resources to replace the oil then do it. I found it easiest to do it on it's centre stand and I've lost a dowel into the engine before when I did a job with the bike laying down and let me tell you it's not a nice feeling! Also, you can run a magnet through the oil tray afterwards to see if anything has been damaged in the engine.

3) You will also need to remove 2 of the bolts from the oil filter later, so may as well drain the filter housing and remove the filter now. The coolant reservoir will also have to be detached and tucked out of the way

4) Next my recommendation is to drain the coolant. It can easily be drained by removing the bottom left 8mm hex bolt and removing the lid from the radiator. Just watch you don't lose or damage the copper washer. Once again, I'm sure it can be done while maintaining the coolant, but the hoses that connect the pump are really short and rigid and I found it really difficult to operate with the rear hose attached. If you can drain the coolant and get the pump out of your way you can avoid the near-disaster I had when I disconnected the hoses halfway through the job and nearly filled up my exposed engine with coolant (D'oh)! Remove the inward facing hose from the pump now, so if any coolant comes out it's not going into your exposed engine. Might pay to stuff it with a rag too.

5) Remove your RHS footpeg and detach the rear brake lever. Pretty self evident how to do it, and it gets them out of your way for later.

6) Loosen the lock nuts at the bottom of your clutch cable and slip it out of the bracket. Lift the little tab on the push lever (the little arm thing) and take the cable out of the slot.

7) You might be able to take the whole cranks cover off with the clutch cover still attached, but I found it easier to remove the clutch cover first. Remove the bolts around the clutch cover and remove the cover. You'll have to give the arm a twirl as you lift it off to disengage the axle from the push rod.

8) Disengage the 2 oil lines leading in and out of the oil filter housing. Make sure you keep the 2 copper washers on each bolt undamaged.

9) Remove all of the allan key bolts from around the crank case cover. The crank case will stay in place because there is a bolt behind the water pump that will hold it there, but it will leak oil, so have your tray ready.

10) Next the water pump comes out. Ensure you've replaced the drain bolt, then remove the 3 allan key bolts that attach the pump to the crankcase. The hex bolts keep the pump together, so they can be left as is.

11) Behind the pump is the last allan key bolt. Your crankcase cover may want to drop away when you remove this so make sure you're ready. Once removed the cover is ready to come off, shouldn't require too much force and if you can be gentle to try preserve your gasket then it's probably a good idea. Apparently you can use razor blades to help separate the gasket cleanly, but minus a bit of a mess when I did it.

12) Now you're in! The rest is pretty easy. The big 36 mm nut behind where the water pump used to be is your culprit. If there's any play in that or the gears behind, then that is your issue. Fold the tab of the washer behind back form the edge of the nut by tapping it gently with a screwdriver. After I did this my nut wasn't even finger tight, so I was pretty confident at this point that I was on my way to solving it.

13) Re-attach your rear brake lever. Take a clean rag, form a dense little roll with it and wedge it between the primary driver gear that your nut is on and the gear behind the clutch. After you've applied some loctite to the nut and finger tightened it, have a minion press on the bike lever for you as you tighten the nut with your torque wrench and 36mm socket. The rag and the brake should be enough to get to the recommended torque of 110Nm.

14) There should be 2 tabs on the washer behind the nut, try line the flat of the nut up with the fresh tab if possible. I couldn't get the fresh tab lined up, so I used the one that had been folded before and then folded the 2 edges of the fresh one over the corner of the nut, kind of like the first step in making a paper airplane.

there should be no play in the nut or the gears behind. If so, congratulations, you probably just fixed your bike!

15) Before you put your side cover back on you probably need to clean the raggedy old gasket off. Make sure you don't scratch the steel! I found the best solution was to take a wedge I cut out of an old bank card and grip it with some vice grips. This made a good scraping tool that didn't scratch.

16) I didn't have a new gasket, but luckily I was carrying some liquid gasket, so applying a modest strip of that all the way around and re-fitting the side cover was a cinch.

17) Replace all of the bolts where they came from (may as well torque them to spec if you have the tool), re-fit the water pump and oil filter and re-fit the clutch cover.

18) When you re-fit the clutch cover it will probably not be biting the axle enough. If so, loosen the bolts, pull the cover out just a little and rotate the push lever anti clockwise until you feel it click. Re-attach the cable, adjust to roughly how it seemed before and test how it feels. As long as it's biting roughly where it should you can adjust at the micro level with the lock nuts. If not, loosen the cover and do the axle thing ^ again.

19) Now re-attach what needs to be re-attached, fill her with oil and coolant and that should be it! It's actually quite an easy job. Hopefully she'll be singing a sweeter tune now, just remember when you start her up again that you're in 5th gear!

Please, if I missed anything, or said anything that blatantly wrong please let me know. And once again, thanks for your help!

Cheers!
Rowan

Find more on my RTW at Facebook.com/motozoa

Cheers! That was interesting.