Topic: Magic self-loosening cylinder stud nuts

[the-chauffeur]

Hey gang.

Engine's out of the 750 K2 again 'cos I thought I had a problem with valve guides leaking oil, but having yanked the head off, it looks like I'm wrong.  The key symptom was oil in the far right hand exhaust, although all of the piston heads look pretty coked considering they had only done 1,000 miles or so since last assembly.  So it seems that it's more likely to be leaks though/around the head gasket.

What I can't get my head round is how some of the cylinder head stud nuts managed to work themselves loose over the last 1,000 miles or so.  Before the engine went back into the frame last time, I torqued the nuts, left them for twelve hours or so and re-torqued them.  When I took the top off, some of them were barely more than finger tight - the studs themselves (heavy duty) were fine and secure, but I'd say four or five of the nuts seem to have loosened off - hence the leak hypothesis.

Am I alone in this (he says sheepishly)?  And more importantly, how do I stop it happening next time - is threadlock my friend?

Thanks all

Neil

[MCRider]

Wow that's odd. I would have to suspect the head cheeze (gasket) as having crushed more. I'm not smart emought to tell you whats a good gasket and what's not. You have a big bore kit i take it?

[Tnutz]

that is odd....

[MCRider]

And there should be no need for threadlock. Look elsewhere first.

[david 750f]

Try another torque wrench. I had an old torque wrench that was under-torquing..
Good luck.

[the-chauffeur]

Hmmmm . . . good point about the torque wrench - that's an excellent starting point.

In addition, I'm really not convinced about the quality of the head gasket, so I've ordered a new one from Cycle Xchange, together with a new set of valve seats.  Any suggestions for removing the originals (and are there any alternative tools to the Honda seat remover, which seems stupidly expensive)?

Just gotta wait for everything to make its way halfway across the world.

Regards

Neil

[simon#42]

Hey gang.

Engine's out of the 750 K2 again 'cos I thought I had a problem with valve guides leaking oil, but having yanked the head off, it looks like I'm wrong.  The key symptom was oil in the far right hand exhaust, although all of the piston heads look pretty coked considering they had only done 1,000 miles or so since last assembly.  So it seems that it's more likely to be leaks though/around the head gasket.

What I can't get my head round is how some of the cylinder head stud nuts managed to work themselves loose over the last 1,000 miles or so.  Before the engine went back into the frame last time, I torqued the nuts, left them for twelve hours or so and re-torqued them.  When I took the top off, some of them were barely more than finger tight - the studs themselves (heavy duty) were fine and secure, but I'd say four or five of the nuts seem to have loosened off - hence the leak hypothesis.

Am I alone in this (he says sheepishly)?  And more importantly, how do I stop it happening next time - is threadlock my friend?

Thanks all

Neil

your not alone , mine did exactly the same . built it up torqued the head  correctly ran it for 1000 miles , pulled the engine out to re torque the head and all the head nuts where pretty loose . re torqued the head and the next time i took the motor out the head torques where fine . i put it down to the pattern gasket set i used . when i fitted my 836 kit i used a honda base gasket and the cometic head gasket supplied  , ran it for 1000 miles took the motor out [ again ] and re torqued the head , this time the head nuts where very close to the original torque . it wouldn't take a gasket to compress much to make a big difference and i think it has to go through a few heat cycles before this happens .   
well thats my theory anyway neil

[Nikkisixx]

 together with a new set of valve seats.  Any suggestions for removing the originals (and are there any alternative tools to the Honda seat remover, which seems stupidly expensive)?

You can use a cold chisel to pop the valve seats out (usually).  This is not a simple task, but installing new seats and reseating the valves is requires REALLY expensive tools.   

[HondaMan]

First, the valve seats:
1. Why? Are they burned up?  They can normally be recut up to 3 times before the valves run out of margin.
2. Head nuts: If the nuts are used, and the sealing washers, too, but the studs are new, the torque needs to be at the maximum number (15.2 ft-lbs, 16 would be OK with those HD studs). Don't use a "click" type torque wrench: use a beam torsion type. Even though I have a complete set of high-quality "clickers" myself, I find that when they have "clicked" and I put the beam on them, they are ALWAYS too light (even on my car's V-8 head, at 110 ft-lbs). I have also found that, for example, the "click" wrench that maxes out at 20 ft-lbs. is more accurate at 15 ft-lbs than my 45 ft-lb-er (which stands to reason, really...).

Finally, those little 6mm bolts that are buried in the head: it is very difficult to torque the middle ones in particular, and I have found that if they are torqued last, the larger nuts nearby will come loose again.

So, over the years I have come up with a method Honda would hate: torque the head per spec, back everything off 1/2 turn, then torque the small center ones first (90 in-oz), then the large ones, in order, then the outer small ones, then loosen and retorque the small center ones over at the end. Then I check the big ones the next day, just to be sure. I don't generally recommend this to others, unless they are having troubles like yours: I believe (but cannot prove) that it is related to twist in some head castings. It shows up in K0-K2 engines more than in the later ones, in my experience.

The carbon in the head: try dropping the carb needles one notch from where they are now and go down to 7/8 turn on the air screws (I'm presuming your mainjets are 105: if 110 then they need to become 105). This will be a tad lean, but won't hurt anything: it will slightly reduce throttle-snap response for large handfuls of low-end throttle. Use also the X24ES-U sparkplugs or even D7E(S or A suffix). Also try using low-octane fuel: higher octane will quickly foul plugs at city speeds if the plugs are D8E heatrange.

[Gregorymoto]

If you are installing new studs you should torque them down let them sit for 24hr and then loosen and re-torque them let them sit for 24 and do it once more.
Thats what i was i was taught.

[funkdr5]

locktite is great!!

[Simpson]

Finally, those little 6mm bolts that are buried in the head: it is very difficult to torque the middle ones in particular, and I have found that if they are torqued last, the larger nuts nearby will come loose again.

If a head gasket develops a small oil leak... Does retorque these nuts ever fix the issue on the k0?
For instance if the torque is little low from the studs stretching or gasket settling.
Or do you absolutely have to change the gasket out?

[Gregorymoto]

When i have re-torqued my cylinder head i never change the gasket unless i pull the head apart. I just back the nuts off 3 or 4 turns and re-torque.

[MCRider]

Finally, those little 6mm bolts that are buried in the head: it is very difficult to torque the middle ones in particular, and I have found that if they are torqued last, the larger nuts nearby will come loose again.

If a head gasket develops a small oil leak... Does retorque these nuts ever fix the issue on the k0?
For instance if the torque is little low from the studs stretching or gasket settling.
Or do you absolutely have to change the gasket out?

I have heard/read that retorquing without changing the gasket often works to stop a leak. No first hand experience and would like to hear from others.

[Simpson]

Finally, those little 6mm bolts that are buried in the head: it is very difficult to torque the middle ones in particular, and I have found that if they are torqued last, the larger nuts nearby will come loose again.

If a head gasket develops a small oil leak... Does retorque these nuts ever fix the issue on the k0?
For instance if the torque is little low from the studs stretching or gasket settling.
Or do you absolutely have to change the gasket out?

I have heard/read that retorquing without changing the gasket often works to stop a leak. No first hand experience and would like to hear from others.

I'll let you know soon. Getting ready to try it.   

[noexit]

The problem with clicker torque wrenches is that they need to be recalibrated from time to time. They go out of adjustment from use and rough handling. My old 25-150lb Craftsman that I got from my grandpa is several pounds out of adjustment.

To keep them from going out of adjustment, always reset it to it's lowest setting after using it, store it in it's case, and don't drop it. If you have a Snapon or Mack or other high end brand, the manufacturer will calibrate them, but if you have a cheaper brand, good luck finding someone to work on them. One hint is that many cheaper brands, including craftsman are made by Danaher (as are many of the cheaper, but still quality hand tools out there).

Also affecting accuracy is the torque range. A 25 - 150 lb wrench won't be as accurate in the lower 1/4 as in the top 1/4. For most uses on our motorcycles, you're better off using a wrench measured in inch pounds. I use a 25-250 inch pound clicker (250 in/lbs is about 20 ft/lbs).

[NitroHunter]

When you get a Snap-on torque new wrench off the truck, it's calibrated accurate at 80% of it's max rating. For a nominal fee they'll send out for recalibration any of their older ones. 

If you are torqueing to the correct ammount for those HD studs (about 22 ft/lbs) and the studs are not pulling out of the case, then I'd replace the head nuts. Their threads begin to loose their shape (pulled over) with repeated torques, thereby loosing clamping force. This is far more of an issue with the nuts than a true rolled-thread stud. I've observed 3/8" grade 8 nuts loose 20% clamping force on the 3rd torque.

If you had a copper head gasket, it could be annealed and reused indefinitely...
 

[Big Jay]

our studs should be torqued to 22 ft lbs.

[dave500]

i havent used a copper head gasket on a four stroke,but in the past on air cooled dirt bikes we used to anneal the copper head gasket then spray it with silver paint,never ever had any issuses,,different kettle of fish i know,but an old practise.

[the-chauffeur]

Wow - some thought-provoking stuff there!  Fantastic.

The observations about the accuracy of the torque wrench are very valid - although even at 50% accuracy, the nuts were tighter when I did them up than they were when I pulled them.  In my case, I reckon I've got a combination of factors that I've been fighting with/suffering from - a poorly calibrated torque wrench, a crappy head gasket and dodgy nuts(!?!).  

At the same time, I'm kinda confused by the number of different figures for the 'right' torque settings for the nuts - in this thread alone there seem to be a few differing opinions and this article - http://forums.sohc4.net/index.php?topic=38253.0 - on how to rebuild the engine from the early 80's says 19lb/ft.  I'm all for making sure the whole thing is completely sealed - and if I had my way, I'd probably end up cranking them on 'til I couldn't crank no more (although I doubt that would do the engine any good whatsoever) - but I don't wanna go mad.

And in answer to one of the questions in HM's post, I was asking about new valve guides 'cos I've got a set on order.  Until I'd pulled the top off the engine, I was figuring that the oil in the right hand exhaust had got there by seeping down one of the guides.  I know different now - it was seeping past the crappy head gasket - but I thought I might as well fix the new guides while I was in there.  And yes, I know I should fault-find first, but valve guides are made of unobtainium in the UK, and knowing Christmas was crashing towards me, I thought I'd take a chance and shoot first.  Still, I guess I can just flog 'em on eBay when they eventually turn up.

So it looks like my best bet is to fit the new (Cycle Xchange) head gasket - any helpful hints on pre-treatment greatly appreciated - leave the old valve guides where they are and fit new (again) valve seals, re-lap the valves, get myself a new set of nuts and find a decent torque wrench.  Not that tricky, really.

Two other questions - the article mentioned above says something about putting Hondabond or Gaskacinch or other sealants on some of the o-rings in the head . . . does that wisdom still hold convention? And any set-up guides for using adjustable cam sprockets and timing wheels (again, Cycle Xchange)?

Thanks all.

Neil

[mcpuffett]

Hi Neil, i use Hylomar Blue sealant put some on the 3 pucks that go under each cam tower to seal them  cheers Mick.

[Jerry Rxman Griffin aka MuthaF'er]

Neil,

You had earlier stated valve SEATS. Thats a major can of worms that would better be dealt with by purchasing another used head. GUIDES is another reasonable story that makes sense.

Stick with Big Jay on the torque. He makes the heavy duty studs you have. 

[the-chauffeur]

Ah yeah - my bad . . . sorry everyone.  Valve guides . . . I meant valve guides.

Arse.

[bryanj]

DO NOT under any circumstances put anything on the "O" rings in base or head gasket or you will fcuk your cam and bearings

On the other hand DO use something on the rubber "pucks" that look like pontefract cakes---I can use that analogy as you are also in UK

[ev0lve]

DO NOT under any circumstances put anything on the "O" rings in base or head gasket or you will fcuk your cam and bearings

On the other hand DO use something on the rubber "pucks" that look like pontefract cakes---I can use that analogy as you are also in UK

Totally. FCUK will also make you dress like this













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