Fit new O-rings to each cylinder spigot?????

[BigBoreSwede]

Hello.

According to the "Holy Bible" there should be O-rings on the cylinder spigots. This makes me go since I simply don´t know where to put these O-rings.
It was not any O-rings when I lifted the cylinder from the bottom.


Hmmm.......


/BigBoreSwede

 

[arborman5000]

If I understand what your talking about I had 2 orange o rings around the cylinders. There is a groove on bottom of head where sleeves extend out of head. Only know because I just took mine out. Hope that is what you were looking for

 

[angus67]

ya. big orange oring goes around cyliner sleave where the aluminum finned part stops. its supposed to keep oil from seeping up and around sleave, and if that happens, could overheat engine because of lack of heat tranfer.

 

[5twins]

Yes, just as described. They should be the biggest o-rings in your gasket set. You can see them here, in place, on my buddy's motor as we proceed with the re-assembly .....

 

[XSRob]

Hi BigBoreSwede.

As you have a 750 conv on original cylinders the groove would mostly have been removed when the bores were machined to take the new bigger sleeves. Mine is like this also but not got around to bolting it all down yet.

Would be interested to hear what others have done and if they leak or not.

 

[angus67]

good point. Ive readsome leak, some dont. maybe a bit of overengineering from the factorey.

 

[BigBoreSwede]

Okay, I´m with you guys. Thanks!

At the pic "5twins" shows there´s a stock gasket and the O-rings. With the 750-gasket kit this "special" gasket is included (pic of the old one). Maybe the metal ring is the substitut for the O-rings.

Now there is possible I´m totally "talking out of my ass" since I don´t remember if this gasket (pic) is the for the bottom or the top-end......stupid

/BigBoreSwede

 

[gggGary]

Yeah pic is a head gasket.

 

[BigBoreSwede]

Shit........shame on me

Guess I´ll need to take a REAL good look tomorrow (it´s night here in sweden now, should be sleeping)

/BigBoreSwede

 

[nj1639]

On an aside....they say that once you can use vulgarities of a foreign language in their proper context that you are fluent in that language, or at the least, well on your way!(or something like that)
Congratulations!

 

[pyroman]

night in Sweden, hell thats only beer-thirty in Texas.............

 

[BigBoreSwede]

Hello.

Here are some new pics on my cylinder the new O-rings/gasket I got from Athena. There´s a groove around each spigot but the ring does not seem to fit. Maybe with some pressure? Why would these O-ring be included in the set if they don´t fit

According to Heiden Tuning the base gasket is NOT to be mounted with gasket cement. It´s a "special".
Look at:http://www.xs650.biz/p/28/2076/mo74-cg|22=1/#18-0752-premium-big-bore-gasket-set

But to me the base gasket looks normal......green and all

I´m still a bit confused

/BigBoreSwede

 

[XSRob]

I guess if the groove was opened as the barrels were machined, before the sleeves were pressed in, the o'rings could have been used. I didn't think of it before now.

Most gasket sets are universal and contain some bits you might not use, its just cheaper to produce them that way (o ring is, what, 5 cents?).

IMHO I would say don't fit it. You could just put a small amount of sealer around the groove- but not on the gasket.

 

[BigBoreSwede]

Could I maybe put on some sealer instead of the o-rings in the grooves....or what´s left of them?? Maybe that´s a good idea

/BigBoreSwede

 

[nj1639]

good point. Ive readsome leak, some dont. maybe a bit of overengineering from the factorey.

I've heard the same though I put them on mine when the top end was rebuilt. I don't see where it would hurt trying to stretch the O rings to fit as long as they don't screw up the green base gasket (keep it from sitting flat)
No sealer on the base gasket.

 

[NoValidTitle]

So is anyone running theirs without those rings? I just dropped my cylinders on last night and didn't notice those rings until I was done and the service manual didn't mention them.

I remember reading once the pistons are in the cylinders if they are removed the cylinders should be honed. Is that true if it's never been run? I have brand new cylinders/pistons/rings but I don't want to pull it all out if I'm going to have to get them honed.

 

[angus67]

if its never been run, you dont have to re-hone.put it together, and take it apart allday long if you like.

 

[radio one]

Just finished rebuilding the top end on my 78 XS 650. New rings and valve job. Unfortunately I just discovered that I failed to install the new rubber gaskets that go around the bottom of the cylinders. Does anyone know if this is a "do over" or if I can get away with running without the O-rings. Damn.

 

[TwoManyXS1Bs]

Hey, radio one, here's a way to look at it:

The cylinder dissipates its heat through the finned cylinder block by solid contact using interference fit (hole in block is about .003-.005" smaller than sleeve diameter). In the cold state, there's quite a bit of interference fit pressure between the sleeve and aluminum block. This tight fit loosens up when heated. In fact, when resleeving, often only about 250-300°F is necessary to have the sleeves 'drop' out of the block (aluminum heat-expands more than iron/steel).

Your engine runs at this temperature, so the fit of sleeve to block is practically nil when running hot. Without the o-rings, oil can migrate up the sleeve, contaminate the interference fit, and reduce the heat conduction.

So, there's the risk factor. Do you want to chance it?

 

[mrriggs]

I left the O-rings off of my cylinders the last time I put it together. If they are meant to keep oil from seeping between the jugs and sleeves then there is major design flaw that prevents them from doing that. Look at the case where the jugs seat, there is no support in the center. The base gasket and o-ring just kind of hang there with oil all around them. Only the front, back, and outsides of the cylinders have a land to hold the o-ring into the groove which tells me that's intended purpose is to prevent external leaks at the base. There is already a gasket there for that so the o-ring appears to be unnecessary.

If you are putting together a motor and have fresh new o-rings then slap them in there, couldn't hurt. I left mine out since I was just swapping the top end from one engine to the other and didn't have new o-rings. The old ones were all stretched out from hanging down in the center and no longer fit in the groove. I definitely wouldn't tear down a motor just cause you forgot to put the o-rings in there.