cylinder head dome nuts

hi all, i'm in the process of renovating my xj600, its stripped down at the moment, i am going to have the engine blasted later. but i noticed the cylinder head domed nuts are rusty, i have obtained replacement stainless steel dome nuts, question is , is it ok to replace them one at a time, without disturbing any gaskets or seals, i have the torque wrench to torque them back down.
thanks
stu :?

 

I'm interested to hear this answer too.

I have the same issue, and it really detracts from the look of the motor...but I hate to disturb a well-seasoned head gasket seal...

 

I did mine one at a time, torquing each one before removing the next. Be sure to replace the washer and use lube on the nut before tightning.
Where did you get the stainless head bolts? Just curious because I had to order mine from Italy.

 

-Where did you get the stainless head bolts? Just curious because I had to order mine from Italy.

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eh,.? .........local hardware shop, stocks most s.s. items, although the originals are a 8mm thread size but a 12mm spanner size, with a shoulder washer on the bottom. if you're after those in s.s. then good luck.
the ones i got off the shelf are 8mm thread size and a 13mm spaner size, without any shoulder, so i got some s.s. 8mm washers to go under them. i changed one in the centre today as the dome had rusted through, i had to carefully chisel it off using a thin chisel down either side of the barrel stalk managed it without any damage

ps assume you mean the dome head nuts, not bolts? :?
stu

 

BE CAREFUL.

If your XJ is a "first gen" (aircooled) XJ motor (and I suspect it is) and has cap nuts ("dome" nuts) like the rest of our XJs, then the two on the RH side get copper sealing washers, not just normal washers.

Unfortunately, there isn't a '91 XJ600 in our North American parts fiche, so I can't speak definitively. Just be careful.

 

-If your XJ is a "first gen" (aircooled) XJ motor (and I suspect it is) and has cap nuts ("dome" nuts) like the rest of our XJs, then the two on the RH side get copper sealing washers, not just normal washers.

Unfortunately, there isn't a '91 XJ600 in our North American parts fiche, so I can't speak definitively. Just be careful
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oh.....ok......thanks for that. yes its aircooled and looks fairly simular to u.s. 550/650 regarding the dome nuts, from what i;ve seen on here, i'll check the haynes tomorrow and get some copper washers if thats the case,,
yes i know theres no 600cc parts listed,
i'm trying to source some rubber "donuts" as you call them ,for the cam cover bolts, they seem to be unobtainable over here, u. k.
would the 550 or 650 be the same
cheers
stu

 

They might be.

Our YICS motors have two sizes/styles; see pic below. There are four of the larger ones, on the inner bolts; and eight of the smaller ones on the outer bolts.

Yours might be like the later Seca II 600s (Diversions over there?) but if yours has the two different styles as pictured below then they're probably common to the 550/600/650/750s and you can get them from XJ4Ever.

 

yes, mine are exactly like that, with the 2 different sizes, so i may order from xj forever, if nothing turns up :lol:
my xj 600 is the pre diversion 1991 but the diversion started production in 1991, so overlapping mine, so i have to be extra carefull when ordering anything over here to stress "pre diversion".
cheers
stu

 

oh,, and-checked the haynes manual and the 2 r/h dome nuts have copper washers underneath,havent taken those off yet. :roll:
stu

 

Hey Fitz, why the copper on one side?

 

The copper washers seal the oil supply gallery to the camshafts. Oil is delivered to the head around the cylinder studs.

 

Ahh...interesting! Thanks!

Yeah I can see where that could be a problem. I couldn't for the life of me figure out why it would have anything to do with the head gasket sealing....

 

There's even more to it; and not surprisingly, we just had this pop up with another member.

Those copper washers are the seals at the top ends of the head-supply oil galleries. At the bottom, those same galleries are sealed by o-rings around their dowel pins, Yamaha didn't rely on the head gasket alone for that important seal.

Those two bolts pass through holes much larger than their OD, which form the oil supply feeds (under pressure) to the camshafts and head. The softer copper washers are needed to seal these oil-pressurized "tubes."

Just another example of Yamaha's elegant "sophisticated simplicity" of design which is why the XJs are still around. We just have to be careful to know what we're doing.