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Torquing Head Bolts

  • Thread starter Thread starter rlloydl
  • Start date Start date
R

rlloydl

Guest
Hi,
So I am the original owner of a 1980 GS 850g. For the first 10,000 miles,
I serviced the bike at the local dealer. After that, I performed the maintenance tasks. I currently have about 38,000 miles logged on the bike. I have never performed the PM of checking/tightening the head bolts and prescribed by the service manual.

Should I start now? Are there any downsides to disturbing these bolts that have not been touched in 25+ years?

Thanks
 
rlloydl said:
Hi,
So I am the original owner of a 1980 GS 850g. For the first 10,000 miles,
I serviced the bike at the local dealer. After that, I performed the maintenance tasks. I currently have about 38,000 miles logged on the bike. I have never performed the PM of checking/tightening the head bolts and prescribed by the service manual.

Should I start now? Are there any downsides to disturbing these bolts that have not been touched in 25+ years?

Thanks
Click to expand...

If nothing is leaking don't mess with them. My bike and your bike are 34 years old, I have never touched the head bolts and I have 56,000 miles on it.
 
I'd check them if you want to avoid leaks. You need to crack them loose before making them up to the proper torque. You might want to use a breaker bar to break the nuts loose, before using your torque wrench to tighten them.
 
Don't mean to hijack a thread but, I was just going to ask the same question. What is the torque for them? I removed the chrome ones so I could repaint my motor. Also what is the torque for the cam cover bolts?
 
Definitely should retorque them. Mine were about 75% of what they should be. I didn't have any leaks--yet. Still none.
 
It makes more sense to me to retorque them before it springs a leak than to try to stop a leak after its leaking. Once the oil finds a path it's harder to stop it. At least that seems right to me.
 
Thanks for all the replies GSR members!
I was sort of on the fence with this issue. Your responses seem to reflect a
divergence as well.

While this issue has been in my mind from time to time (I do review the maintenance schedule in the service manual on a semi regular basis), I have been hesitant to just jump into this one. I would presume the factory had a good reason to say to check/tighten them every 4000 miles.

One final question on how to proceed; if I follow Nessism's advice to loosen slightly before torquing, should I do one nut at a time or should I loosen all
in a the reverse sequence of how you would normally tighten head bolts after
replacing a head. And if I loosen them all, should I just continue and remove them all and apply some fastener assembly lube while I am at it before I go through the torque sequence?

Thanks,
 
when I did mine for the first time they seemed tight but then I cracked one loose and re torqued and they did about 1/4 turn past what they where when I re torqued, I would do reverse sequence loosen and re torque one at a time, I also put put a small dab of moly lube on each one just a small amount.
 
Duplicate what you would do when torqueing the head down for the first time. Follow the tightening pattern in the book (or if you don't have one for a particular engine, start from the centre and work out in a spiral pattern).
Re-torqueing an ancient engine is complicated by years of grime and corrosion in the threads - you might not think it's there, but it will be, in some of them. So, you have to slacken off, but you can't go slacking off at random, you must slacken off in the reverse of the tightening pattern and the entire head must be allowed to stress-relieve.
I don't lube the nuts or studs, apart from what would have been there if the engine was being assembled as new or a re-build - ie, the lightest coating of oil, but not actually lubed as such.
If you lube studs and re-torque, you'll be stretching them by an unknown amount and torqueing them to book torque is likely to exceed the desired stretch by at least 10% and likely as much as 20%. You're not going to break anything, but this leads to an uneven distribution of clamping forces on the head, might possibly lend to an early head gasket failure or simply promote an oil leak you were trying to avoid.
See? It's a bear pit.
Slacken, clean, don't lube, re-torque in an orderly manner.
 
It won't hurt to spray each nut with PB Blaster or similar before retorquing. I'd do one at a time, following the number order cast into the head.
 
Nessism said:
It won't hurt to spray each nut with PB Blaster or similar before retorquing. I'd do one at a time, following the number order cast into the head.
Click to expand...
Oh, yeah; I'd give them a squirt of PB / WD, etc then wipe it away with a rag, just to approximate the very light oilyness of the first build.
In the order given, it's what down to what you find works for you; I prefer to let the head have a chance to even out and be clamped evenly again. It might not make much difference on a road bike, but it might help. I first started doing this when it dawned on me many years ago that cooking, bog-standard bike engines we were used to were actually putting out the same levels of BHP/L as were worked hard to be achieved in many levels of club car racing and those HP were hard-won and hard to keep. Our makers, with their designs, had managed to do this with an astonishing degree of reliability, but it would surely pay us to be careful in the details, to retain that outstanding power level and reliability. Hence, why I do it the way I do.
Some/most don't, and that's fine - says a lot for the tolerence of these engines.
 
I'll mention that I order minimize false torque readings the proper torquing technique should be used. Smooth pulls till it clicks. You can search for more details I have posted in the past. Retorquing comes up time to time.
 
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