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Discussion Starter #1
Yep, major shit!

I've been on a nice trip on Saturday on my 2009 989R. I heard some weird noise from the engine, like a little bell. I thought that cam chain tensioner went and since I was near home I thought it will do.

Well it didn't! The noise was from exhaust cam sprocket banging on the cam flange and eventually both of them snapped. Luckily I was on a straight part of the road, going slowly and I pulled the clutch in very fast.

I don't know how this happened. It probably is my fault since I was doing the valve clearance adjustment job a year ago. But for the bolts to just shear off? I have done this a few times on the MVs, so...I really don't know...

Well, I found both of the bolts and all the Nordlock washers. Bolts and 2 washers were in the head and 2 washers in the sump.
I pulled the head and the valves didn't touch the piston, can you believe it? The exhaust valves leak a bit, so I will do the valve job, put everything back together and call it a day. Of course, I pulled the oil pump and will clean everything well before reassembly.

Looking at the bolts, they didn't untighten as there is still a large part of them sticking out of the cam flange. The bike has around 17000 km.
Any one with an explanation?
 

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looks like a major disaster. i am happy no accident happened
and wish you the best with fixing the damage. can it be that
the cam shaft actually remained fixed with the exhaust valve
closed, while the cam chain was still turning?
 

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Discussion Starter #3
Yes, the camshaft remained fixed, the sprocket was turning on the camshaft.

In the 4 cylinder, there is a valve (or a pair) opened at all time, so it is a miracle that the piston didn't hit the valves.
The only damage is some seals that I have to buy and a lot of time.
 

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Looks like you got lucky. In a strange kinda way.
It's good that you can do the work yourself.

I appreciate the pics as I've never been into an MV before. I do porting/cylinder head rebuilding so it's very informative.

I know it sucks but would you mind taking pics of the ports and combustion chambers while you're in there?

I was going to offer to port it for you while it's apart but I see you're far away from me. If you don't mind the down time let me know.
I have references and you can see some of my work on youtube if interested.
 

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Discussion Starter #5
Will take pictures for you, no problem.

Thanks for the offer, but I don't like the idea of the head being shipped half across the world and then back. If I would live near to you, I would do it in a heart beat.
 

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All fasteners stretch. The cam sprocket bolts were stretched once when the engine was assembled and then again when you set the valves. So, perhaps when you re assembled the engine you fastened the already stretched bolts to the correct torque and that was just too tight which would cause them to shear.

I'm just guessing here but it sounds good, doesn't it? I'm sure Noel would have an opinion on this and the engine builders too.
 

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Yep, major shit!

I've been on a nice trip on Saturday on my 2009 989R. I heard some weird noise from the engine, like a little bell. I thought that cam chain tensioner went and since I was near home I thought it will do.

Well it didn't! The noise was from exhaust cam sprocket banging on the cam flange and eventually both of them snapped. Luckily I was on a straight part of the road, going slowly and I pulled the clutch in very fast.

I don't know how this happened. It probably is my fault since I was doing the valve clearance adjustment job a year ago. But for the bolts to just shear off? I have done this a few times on the MVs, so...I really don't know...

Well, I found both of the bolts and all the Nordlock washers. Bolts and 2 washers were in the head and 2 washers in the sump.
I pulled the head and the valves didn't touch the piston, can you believe it? The exhaust valves leak a bit, so I will do the valve job, put everything back together and call it a day. Of course, I pulled the oil pump and will clean everything well before reassembly.

Looking at the bolts, they didn't untighten as there is still a large part of them sticking out of the cam flange. The bike has around 17000 km.
Any one with an explanation?
Hi Miha,how LUCKY the head of the allen screw didn't damage a cam lobe or get caught in the chain:jsm:using a screw with a shank(non threaded section)the width of the cam sprocket would be my approach.Cheers Steve
 

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lucky Miha

Miha;
my friend you got VERY lucky:drummer::drummer:

the bolts failed in tension......they're in shear

tensile fatigue life in bolts runs from~ 2x10^6 to 6x10^6 cycles

junk bolts or over torqued (i doubt it was by Miha)
 

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Discussion Starter #11
All fasteners stretch. The cam sprocket bolts were stretched once when the engine was assembled and then again when you set the valves. So, perhaps when you re assembled the engine you fastened the already stretched bolts to the correct torque and that was just too tight which would cause them to shear.

I'm just guessing here but it sounds good, doesn't it? I'm sure Noel would have an opinion on this and the engine builders too.

Maybe you are on to something. I didn't replace them before, sure did now!

However, we are back running. See some picture of the rebuild.

I replaced the valve seals ( we call it ''teflons'' ?? ) and did the valve job; don't know how it is called; you brush the valves against the seats with special paste to get them to seal tight again. Exhaust ones were leaking a bit.

First and 2nd pic: head ready to be assembled.
3rd: niceee
4th; head in the place
 

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Discussion Starter #12
I had a lot of troubles with valve play; I removed the cams 3 times, replacing and switching the valve pads. Also, I don't have a large stock of them, so had to grind some of them manually with sandpaper and glass to the correct thickness.

After that I put back in the oil pump, clutch and oil sump. Put the engine back in the bike.
Pour in the oil and start it without fuel so the oil pump sucks the oil and sends it around without the engine actually running.

Put all other stuff back in and it started in first try.

Didn't take many pictures after that I am afraid;

1st: putting the engine back in.
2nd: up and running, just a few plastic pieces and going for a test ride.


That's pretty much it. It is pretty much a miracle that valves have not been bent. I just replaced head gasket, valve seals, sump gasket and that was it for the material cost (160€). Somewhere around 40 hours went in to this project as I am very nit picking when it comes to cleaning every thing before putting it back together. I cleaned the oil pump, oil radiator, lines, washed the engine inside with gasoline to put any possible chips away, cleaned all the oil passages etc.
 

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Great job Mate, no shame in taking you`re time ,"cleanliness is next to godliness." Hope the test ride is perfect,let us know.
 

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Discussion Starter #16
Made a proper shakedown this past Sunday... did 300 km, all went fine.

Now going to Dolomiti mountains in Italy in next few days, hope everything will be OK.
 
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