valve adjustment: torque question

[pdx_r100s]

I have another question about retorquing these cylinder head nuts. When I went to retorque the four nuts I backed off 1/4-1/2 turn and then torqued them in a cross pattern using stages--I read on one write up to use 17, 20, 25 ft lbs, so I did that. Three of the four nuts were totally smooth, but the fourth felt like it was binding a little bit as I got towards 25 ft lbs. This worried me--I read that this might be a sign that the nut should be oiled, so I backed it off, added oil to the threads, and tightened down again. It did the same thing--not a smooth pull like the others.

I was paranoid and got another torque wrench--this time a digital rather than the click style I had. The nut did the same thing. It gets to 25 ft lbs, but it definitely feels like its binding a bit, which then requires me to turn further before it gets to the specified value.

Do you have suggestions about what to do in this case?

thanks

[Rob Frankham]

Make sure the faces where the nut meets the pillar block (one both the nut and the block) are smooth and clean...

Run a thread clearing die down the thread on the stud and a tap through the nut.

When you loosen one heas nut, make sure you loosen them all and go through the complete diagonal tightening sequence again or you risk a warped head.

Rob

[pdx_r100s]

Thanks—I will try that. Do you know what the bolt size is? Would it be worth buying a new nut, and if so, is that a special part?

One other question—would it be ok to leave the two nuts at 6/12 o clock tight while I re tighten the four on the rockers, then loosen and retorque those? I think I read somewhere about somebody using that method.

[Rob Frankham]

The thread size is 10 x 1.5 (metric of course) and, yes, it is a special part. The face that goes against the pillar block is specially faced and it has an non standard hex size (15mm AF... a 10mm nut would normally be 17mm AF).

My rule of thumb would be that, if the thread is sound and it runs onto the stud by hand without snatching, it's fine. If not, run a die onto the stud and a tap through the nut. If all is now fine, well and good... otherwise replace the nut and, if it's still snatching, the stud.

I always loosen all of the nuts and retorque them in sequence... May be being a bit paranoid but, in my view, better safe than sorry.

Rob

[pdx_r100s]

Thanks for all of that info. I had read different things about only loosening the two nuts for each rocker arm assembly at a time—so I wasn’t sure if there was more risk of deforming the head if you relaxed them all at once. All other valve adjustments I’ve done on other bikes haven’t required any retorquing of cyl heads, and I’m working with a ~60 dollar clicker style torque wrench—not the cheapest, but also not the most precise, I suspect. It is brand new though.

[pdx_r100s]

sorry for all of these basic questions...still learning a lot here. If i'm going through the process of retightening all six bolts in the cross pattern, do I loosen them all slightly, and then retighten, or do I go one at a time--loosen that nut then retorque, on to the next? This is another detail I haven't understood in some write ups.

thanks

[Kurt in S.A.]

I don't see the big issue with just loosening the one you want to check and then retighten...or doing the top and bottom bolts to try and snug up the rocker blocks. I can't imagine that there is a significant danger of head warpage doing that. I also note that the torque situation on the upper and lower bolts is very different...they come up to torque really quick, more so than the four longer stud bolts. Meaning that they also lose torque quickly when loosened. Just be aware of that.

Kurt in S.A.

[SteveD]

I've always thought that once loosened the process was to re-torque at 3 stages.
All 6 get torqued at each stage together, in prescribed pattern, then onto the next stage.

However, if you're just checking the clearances, there's no need to do the re-torque, maybe unless they're wildly bad.

[barryh]

I've always thought that once loosened the process was to re-torque at 3 stages.
All 6 get torqued at each stage together, in prescribed pattern, then onto the next stage.

However, if you're just checking the clearances, there's no need to do the re-torque, maybe unless they're wildly bad.

I agree and would only re-torque when absolutely necessary. What's the current best practice on re-torquing ? I know it used to be recommended but I haven't done it in 10 years and even then I chickened out at 24 ftlbs. Seems to me re-torquing too often is asking for trouble.

[Rob Frankham]

sorry for all of these basic questions...still learning a lot here. If i'm going through the process of retightening all six bolts in the cross pattern, do I loosen them all slightly, and then retighten, or do I go one at a time--loosen that nut then retorque, on to the next? This is another detail I haven't understood in some write ups.

thanks

The 'correct' procedure 'a la' BMW is to loosen all head nuts by 1/4 turn then tighten them one after the other other, in a diagonal pattern, to each succeeding stage on the tightening sequence... i.e. all nuts to 11 ft lbs then all nuts to 18.6 ft lbs then all nuts to 26 ft lbs. They say this should be done at each service before adjusting the valve clearances but I've never thought that was necessary and I just do it every five or six services if it hasn't been done for another reason in between.

Rob