Question about head bolt torque...

[gggGary]

MUCH less, than the risk of leaks if you DON'T tighten them. IM(maybe not so)HO.

Think about this a little, is it a good idea to have ONE tight bolt and seven loose ones? While doing a retorque the other day ( I re-torque every XS650 that goes on the lift before I even see if it will run) as an experiment I checked how much torque it took to LOOSEN the nuts, well over 50 pounds to crack loose and free the nut from the stud. Don't forget the two bolts under the plugs. 12mm short 3/8 socket and a breaker bar it's a snug fit getting on those two. and the 10mm head small little bolt above the cam chain tensioner, careful not too much torque on that one.

 

[marp68]

You're probably right... Thanks for pointing it out. Just a bit afraid that some nut be stuck and I loosen the studs instead, and end up with a mess. Don't want to risk that when biking season is just beginning.

Just to clear things, it only leaks in one corner of the cylinder foot when driving the bike, not with engine shut off. Would it be enough to retorque only the 8 big acorn nuts, since the smaller bolts doesn't affect the foot?

Is there any way how to notice/hear if the stud is coming loose instead of the nut? No cracking sound etc? What do one do if the stud is coming loose, just retorque it? If one retorque the stud instead of the nut, does it apply the same pressure and holds everything in place?

/M

 

[gggGary]

After oh 8 cylinder head re-torques I haven't broken a stud loose only the nuts. If you did break the stud loose you would re-torque it just like if the nut cam loose.
I think you are making this molehill into a mountain, it's about an hour job if you are fussy and slow and polish the nuts while you have them off.
If you don't do it and the gasket tears or creeps you will be pulling the engine and removing the head and cylinder. that is a bigger project.

I removed the studs from a case one time, I had to buy a stud puller and still couldn't get them all out. Each stud was seriously tight in the case with some sort of lock-tight. I really thought I might break studs before they came out. Later it was suggested heating the case might let them come out without so much struggle

 

[marp68]

Hahaha, yepp that's a little like me sometimes.... To much respect or worry regarding the engine itself. I tend to gather MUCH information before getting into the project. Sometimes maybe to much. But I normally also end up fixing things in the end.

So thanks for taking the time to clarifying things. Will probably do it one of the next coming days or weekend.

/M

 

[marp68]

That seemed to do it. Retorqued the 8 bigger bolts and went for a ride. No oil. Hope it will hold.

Was thinking that I might as well retorqueing the smaller bolts as well. Just in case. According to the pattern theese come last. Can I just continue with loosen and retorqueing the small bolts or do I have to do them together with the bigger ones, that is loosen and retorqueing the bigger bolts from beginning again?

 

[gggGary]

Nope just do em, and do em now! After the 8 head nuts it's just the the two under the plugs and the little one above the cam chain tensioner. The others just hold the cam cover down and do not affect the head gasket.
Uneven torque on heads is bad JUJU. I can't IMAGINE why you didn't just follow the frickin' directions developed and fine tuned by a bunch of XS650 guru's and do it all at once. The two 12mm under the plugs are a bit hard to get at.
Be REAL careful with that tiny one above the chain tensioner but DO it even though it's a pain to get to. A long 1/4" drive ratchet extension with a flex adapter seems as good a way as any to get to that one. Much easier was to do when you had the carbs off. There is a long thin gasket surface the one little bolt clamps together.

 

[TwoManyXS1Bs]

gggGary gary gary, calm down, take a pill...

While your head/cyl retorque logic is correct, you failed to recognise the REAL problem here.
The man was concerned about weepage under #8 and really wanted to focus attention there.
Having MORE torque on that stud was his solution to the problem.

Old scool logic for addressing this type of problem:

If #8 is tighter than the others, then it will leak less than the others.
BUT #8 MUST NOT be over torqued. The others (#1-#7) must be loosened.
If fact, they should be backed-off so there is at least 1/8" of daylight visible under the nuts.
NOW, #8 will weep less than the others and will no longer be of paramount importance.

 

[xjwmx]

I fixed an internal oil leak into a combustion chamber by re-torquing. At 70 mph I was using about 1 qt of oil every 100 miles! Much less oil or none at city speeds.

The bolts under the spark plugs are easier with 1/4" drive.

Here's something I consider very important. Torque wrench accuracy is all over the place, even on new and expensive ones. Use a beam type wrench and if you are turning and see the torque isn't increasing, stop! Even if the reading is way below your target torque.

 

[SolidLex]

5Twins, did you torque the cylinder studs to 30lbs also?

The preference is for the bronze/brass/copper over the O.E.M. rubber ones. Those rubber washers were a screw-up on Yamaha's part. They allow those 4 outer acorn nuts to back off and come loose all the time. They are probably the #1 reason for XS650 head gasket leaks. The bronze/brass/copper washers are soft enough to seal but hard enough to retain your torque.

Now that you own a 650, I'm sure you notice and take a closer look at any 650s you happen to see while you're out and about. What you're going to notice, now that you're aware of it, is that most you see will have leaking head gaskets. Look even closer and you will see those original rubber washers still in place on the 4 outer studs. Changing them out is pretty near at the top of the "Must Do" list when you get one of these.