head bolt retorque.

Edit 7-2014 a lot of XS engines have passed through my shop since this post (in quotes below)
Do the full head bolt retorque! I do, on every engine I intend to start. Every engine, BEFORE I run it. full instructions in lots of good posts below. Loosen and remove the nuts one at a time use oil or anti seize, reinstall and torque.

a bit of editing 5/2022;
5twins revised torque schedule
1653504509063.png

#1 - #8 head studs, remove one at a time, clean, apply anti seize or a little motor oil, torque to 30-32 ft lbs. Start in the middle, work outwards in numbered order is fine.
Then #9 and 10 under the spark plugs, loosen a turn then tighten to 16 ft lbs.
You do do not need to mess with #12 to 15 they do not affect the head or base gasket.
Finally the lonely #11 a 10mm head 6mm bolt that's' a bit hard to find, in front of the carbs, just above the cam chain tensioner. But it's important, seals a long U of head gasket and it's usually loose. A 10mm 1/4" drive socket on a flex joint then long 1/4 drive extensions is about the easiest way to reach it unless the carbs are off. Just a bit snug. I do not trust torque wrenches on 6mm bolts, especially this one, which only has a short amount of aluminum thread to hold it. Go gorilla and you will have stripped the threads out out the head!

That's all you HAVE to know! but the rest of the thread is fun, read along as the collective develops what is now thought of as common wisdom.

Original post 06/2010
"here's 2 cents worth. I bought a low miles 5600 81 special I got everything else going my way but there was a pretty serious head gasket leak. I pulled the gas tank and head stay off. the two bolts under the plugs were not tight at all. so I tightened those and one at a time removed and buffed the head nuts. I put a little anti seize on them and retightened using the ole' arm strain gauge. Drove it and it leaked worse, next day drove it again and the leak had quit. (still plenty of oil you doubting Thomas!) So far so good. So if it ain't leaking I would check those bolts under the spark plugs, the rest of the sleeping dogs, I might let lie."


I no longer recommend letting the cylinder head bolts go, retorque them all. It is the cheapest insurance you can buy on an XS650 engine.

Read this Yamaha service bulletin; the retorque is not just a some guy on the forum it's a Yamaha procedure and they spec lube on the nuts!
full

Odds are very high the dealer never did a head tetorque 30 years ago and it's still needed today.

A "full" set of Yamaha XS service bulletins has painstakingly assembled by 2many here and here. You are so lucky to have found an XS650 to be your ride and a forum like this!
 
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I might do a retorque, follow the pattern in your repair manual and torque the little ones to what the book says and the 8 big ones to 35 ft/lbs. I would even replace the 4 outer big ones rubber covered washers with brass ones like Mike's sells. They hold the torque better than the rubber ones and seal the oil in just as good.
 
aight. So loosen first though correct? do they need any sort of lube on them at all?

still may wait though. I am on a budget this year. No motor work. So i may just leave alone for the summer since i'll have 6 months of down time come october or so. Don't really want to have to tear into if some misfortune happens.

Real impressed with how leak free this one seems to be...my last one had the same miles and i had to change almost every seal.
 
No loosen unless you are swapping the washers. Just torque.
Even on a rebuild the bolts and nuts go on dry.
 
Picking up an old topic. Having a headgasket leak myself.

This can all be done with the motor in the frame, right?
 
You'll need to remove the top motor mount to access the 4 inner acorn nuts. Personally, I use anti-seize on all the fasteners. If it's a head I've never done before, I crack the bolts loose 1st before torquing. They can become stuck on the threads and give a false torque reading if they've been on there undisturbed for years. In other words, they'll read tight on the torque wrench when they may really not be.
 
Yes, you can torque the head bolts without pulling the motor. You just need to pull off the tank and top motor mount.

I always back them off just a hair before re-torquing. Static friction is higher than dynamic friction which is why you should always use a smooth steady pull on a torque wrench.

Edit: Wow, I type slow, there were already two replies in the time it took me to type that.
 
I know you're supposed to alter torque settings slightly for lubed bolts but I never have and I've never had any problems. Like mrriggs said, use a slow steady pull on the wrench.
 
I know you're supposed to alter torque settings slightly for lubed bolts but I never have and I've never had any problems. Like mrriggs said, use a slow steady pull on the wrench.


Will do!

Do you adjust in increments like 2,5kg for the ones that need 3,5kg and then to max torque for the last round?
 
I do torque in increments, maybe starting at about half or 2/3, then 3/4, then up to full spec. The chart above is rather outdated and from an early manual. Yamaha increased some of the values in later years. Most of us increase the spec for the 8 large acorn nuts even more, using 30 to 35 ft/lbs as per the suggestions here .....

http://www.650motorcycles.com/CopperWashers.html

Here's a new chart I "doctored" to reflect the increased values .....

sAxkrCc.jpg
 
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Yamaha increased some of the values in later years.
They also changed the tightening pattern.

I usually do them all in stages to the lightest torque, then the 2nd lightest (not re-doing the previous lighter torque, obviously), then the final acorn torque. Then i go over then again to ensure proper torques.

Antiseize on the acorns is fairly pointless, though can't hurt. They're steel on steel, and protected from the elements, and half of them have oil mist in them.

The other 4+1 bolts IMHO should get a light sheen of antiseize, since they're steel into aluminum - but don't be tempted to over torque.
 
Thanks 5twins, that is very informative.

I thought all the bolts where accessible from the outside, hence no need for dismantling any motor parts?
 
You'll see when you try, the top motor mount needs to come off. The 2 bolts under the spark plugs can be difficult because the points and advance housings partially block access. Removing the chrome covers will help and using a wobble adapter extension on the torque wrench will also help .....

5gJAzEo.jpg
 
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