Question about head bolt torque...

twins, thanks... brass ones are on the way. Glad I asked about the preference/change. I did happen to peek at the outer four yesterday, but without being certain of what I was looking at; they appear to be the rubber ones. I will feel a lot more secure about having taken this additional upgrade/maintenance.

I want to say that my torque wrench is half-inch drive. I need to hunt down one of those angle extensions to reduce the possibility of scowling and street vernacular when I go at the ones under the plugs. :p
 
The stock through bolts are pretty soft. Bud Aksland, who built Kenny Robert's XS engines, didn't like the stock bolts because he said that he had experienced some that stretched slightly. If one or more stretched and others didn't, obviously the head was no longer torqued evenly and distortion occurred.
Bub cured the problem by simply replacing the bolts with higher grade rod stock that was threaded on the ends.
Nevertheless, for the center 4 bolts he still used steel "spreaders" under the nuts. These were approx. 1/8" thick steel and were sized so they fit down onto the head surface. They evened out and spread the pressure, ensuring a higher probability of avoiding any distortion and loss of compression.
For the record, Harry Lillie and Bud both used copper gaskets and torqued the head bolts to 29 - 30 pounds and those engines had additional ccs and higher, race-level cylinder pressures; far in excess of any street engine. Both also retorqued the heads on a rebuilt engine after the first full heat cycle.
Bottom line: copper gasket and no more than 30 pounds on any XS engine.
Craig
 
650, thanks for chiming in. I'm not reassembling after a build - just doing a re-torque on a motor whose history is not known to me - but it's still good information.

My brass washers are on the way. But just in case I can't re-use the existing ones aside from the "Big 8" that I'll be replacing, are Grade 8 hardened steel washers in various sizes available at local houses like Ace or Home Depot? As has been mentioned, I want to use steel that's hard and thick enough, especially since nothing that the(a) PO might have done on this bike would surprise me...

Great info, all!

TC
 
I have found them at True Value. I think as long as they are the prescribed 4mm thick, then they should work fine.
One engine I had, had several thin washers stacked up on 3 of the bolts. Never leaked though, lol.
 
Thanks, Bill!

You know, we used to have a local hardware store called Sewell's that was a True Value store. But they closed years ago... I always thought it was because True Value went away. Now we have Clark's, which is an Ace.

I wondered about the permissibility of stacking in a pinch, but thought it might affect torque retention.

TC
 
Well, I think I collected everything I need today. I managed to get a 3/8" drive wobble extension, as well as a nice 3/8" Autocraft torque wrench that is rated to 80 ft lbs; my 1/2" drive one is pretty monstrous for this job. Got the tank and the top mounts off, and will likely do this tomorrow. Just hope everything cracks loose and torques down with no drama. I'll be replacing 1-8 washers, but plan to re-use the others if they are undamaged. Otherwise I'll have to try to find new ones that are hard and thick enough.

One thing I did notice when prepping is the the plugs on this bike have never looked as good as they do now, since I have been running my single VM, which seems to be properly dialed in. Nice and tan, no indication of fuel or oil fouling, and symmetrical, which surprises me because of the unequal runner lengths. Very pleased about the way those plugs look.

TC
 
I get my grade 8 hardware from Elliot's here in Dallas, it's a True Value store.

Metric grade 8 will have 10.9 on the bolt head.

I wouldn't stack washers.
 
Stainless may be softer but I only use it on the smaller M8 and M6 bolts. They get less torque (14-16 or 7) so I've had no problems with the washers deforming. The original steel washers under the 4 inner acorn nuts may be a bit crusty but I just clean them up and re-use them. They're under the top motor mount and gas tank so you can't see them anyway.
 
I got one through 8 replaced with brass and torqued to round 1 (20 lbs). I got number 9 out easily, but the washer looks pretty thin. No damn way it's 4mm thick... never was. So I'm going out to try to get some grade 8 or stainless for 9, 10, 12-15 that are a little thicker. Don't even know if I'll be able to reach 11 at this point, at least with a torque wrench. I might have to use the guestimator on that one.

TC
 
First off, you don't need brass on 1-8, only 5-8. Second, you don't need thick washers on 9-15, they're through bolts so thickness doesn't matter. You only need thick washers under the 8 acorn nuts.
 
twins -

I put brass replacements under all the acorn nuts because the originals were a holy mess, and because that's what Mike's is specifying as an alternative for the OEM rubber coated ones, and as a replacement for the other four. So I'm covered for thick washers under all the acorn nuts.

Off to get some clean stainless or steel for 9-15.

Glad I caught your reply... just headed out the door.

TC
 
Well, my local Ace was able to hook me up with some Grade 8 steel washers. I got everything torqued to the specs on twins' updated graphic, except that I only used 30 ft lbs on the acorns. I'll go to 35 if someone strongly recommends it; otherwise I'll leave it based on some saying that only 30 is needed.

Gonna clean up on top of the motor (some old ratty PO paint) a bit before I but the mounts back on and button up. I'll check the torques one more time tomorrow, I suppose.

One thing I did notice is that I think I'll be needing to replace seals and gaskets behind the advance and PAMCO housings. The latter seems pretty dry, but the advance has a touch of oil in it. Maybe cold temps, winter weight oil... who knows...

Thanks to all who helped me on this! Now I know how to do it. Hope my little seep goes away, though!

TC
 
On my way out to button up and then touch up some paint on the head cover, guys. Before I put the top mount and tank on, though, should I stay at 30 ft lbs on the acorns, or "leave" a buffer (to 35)? What is the preferred practice there?

Thanks!
 
How did it go?

I have the similar problem, but the corner of nr. 8 at the cylinder foot. Just a small leak at the very corner. I was thinking about only loosen and retorqueing the nr. 8 acorn nut and leave the rest as are, since it's completely dry around them. Would that be okej, or could it twist the cylinder some how?

And if loosen and retorqueing only that outer acorn, would it be okej to not loosen the upper engine brackets? Just the lazy side of me that don't want to remove the tank etc...

When some talk about the black rubber washer, do you mean that it is made completely of 4mm rubber, or just wrapped around a steel metal washer? The engine seem to have been rebuilt by one of the PO a long time ago. The acorn nut washer are black but seem to have been changed during rebuild. Could be rubber, but I don't know if the core is metal.

Thankful for any feedback

M
 
Do em all, they are all frozen on the studs and undertorqued. Really it's not that hard and doing just one when you already have a leak is well, "half assed". There is steel inside the rubber washers. I just retorque on the rubber washers and don't replace them..........I might not be super lazy but I AM cheap!
 
And there's no risk that also loosen and retorqueing the others will make it start leaking around them, then?
 

Similar threads

I
Advance bob weights and springs question?
2 3
Replies
42
Views
991
Its been a long time
I
Orion61
Found fine cracks? at the bottom of my 81, jugs. Was retorquing but that is on hold.. HELP!
Replies
12
Views
1K
gggGary
gggGary
Mannyroad
URGENT HELP to source electric ignition for rephased motor
Replies
14
Views
648
Signal
Signal
SpookyWizard
Popping my XS650 cherry, the Journey so far.
2 3
Replies
43
Views
3K
nj1639
nj1639
Pipes
Fork bushing wear?
2
Replies
28
Views
2K
Pipes
Pipes
Back
Top