cylinder head bolts, torque?

hi all , ive got a problem with my newly rebuilt engine, xj600 euro model,
on first start up today, I have a small leak on the head gasket, just at the point nearest to the rear oil gallery bolt.
I checked the head bolt torque in the Haynes, and it says 22Nm /16ft -lbs.
this seems quite low for head bolts, being 10mm , as the torque for the camshaft sprocket bolts (6mm bolts) is 24Nm/ 17 ft-lbs , and crankcase bolts (8mm) at 24Nm / 17ft - lbs.
I have 2 torque wrenches one ends at 20Nm , and the other starts at 30Nm.
so I did tweak them up a bit to 30NM, and still I have a small leak , but less than it was.
is the Haynes wrong, should I try them a little more, when it cools down
cheers
stu

 

You should not increase the torque any more. To my knowledge the torque values in the Haynes are correct.
Your leak is most likely not from the head gasket, but from the valve cover gasket and the oil is finding its way down to the head gasket gap.

 

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You should not increase the torque any more. To my knowledge the torque values in the Haynes are correct.
Your leak is most likely not from the head gasket, but from the valve cover gasket and the oil is finding its way down to the head gasket gap.
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no the leak is not from the valve cover, I can see the oil mist "puthering" out from the gasket



the leak is between the head and barrel just below the rear head bolt nearest to the spark plug.
so if the torque of 22Nm is correct ,then it looks like the head will have to come off again.
spent 3 1/2 years rebuilding this, and summer is almost done.
stu

 

I would try to find a Yamaha manual before pulling the head, those torque values do seem low.

Just for info, the XJ700 per the FSM is quite a bit higher for M10:



And, per the XJ750 Seca Yamaha FSM the M10 is specified at 23.1 ft-lbs for the M10 P1.25, and the Haynes "Yamaha XJ650 & 750 Fours" agrees. Both the 700 and 750 have a note to add oil, which will effectively increase the torque.

Hopefully, someone has a Yamaha FSM on the XJ600 and can weigh in.

 

Maybe take off the cam chain tensioner and try to lift the head to let the o_ring gasket seat itself.
Long shot but might work

 

Found this link on Seca II, which I am not sure if it is the same. However, it has the similar torque readings as you first mentioned.

http://www.xjrider.com/viewtopic.php?t=670

 

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Found this link on Seca II, which I am not sure if it is the same. However, it has the similar torque readings as you first mentioned.
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yeh, saw that link earlier, it kind confirms what the Haynes says, (but that could be where he got the specs from)

anyway ,started pulling the head this afternoon, another hour tomorrow and it will be off.
should I get a new head gasket, I only fitted it a few months ago , and its not been started till yesterday?
stu

 

Hmm, if you tightened in sequence then all should be ok. I (accidently) went to 19 ft/lbs on my head by misreading the gauge but all seems ok - not really run it for more than a few mins though. If you don't want to risk further tightening then with the head off I'd want to check it for 'flatness' if I were you. Plate of glass and feeler gauges might give some clues.

Good luck

J

 

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Good luck
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cheers, I may need it.
stu

 

Keep in mind that the XJ600 is based on the XJ550, which is based on the XJ400. The torque values for the 650/750 engines should not be used as a guide. The 550 FSM calls for 14 ft-lbs of torque on the head nuts.

This begs the question: does the 600 also use o-rings to seal the camshaft oil feed? The location of the leak makes me suspect that is where the leak is coming from, and tightening the head down won't fix that.

 

thanks everyone, all fixed now. pulled the head , couldn't see anything on the gasket or head / barrel.
but found a small burr, on the head/ barrel locating dowel, which has a rubber seal round it , possibly preventing the head from seating properly
removed the burr with a fine file, till the dowell was a snug fit, in the barrel.
new head gasket and a new seal round the dowell. started up ok and ran with no leaks.
had to re-shim the two # 4 valve clearances, as they were too large , after removing cams, all others were in spec.
got to set the carbs up now.
thanks
stu