Cylinder to case gasket fail

thuban

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Well eat me fer a tater! I ran the bike for about 4 miles at 65 to 70 mph because of traffic and having to keep up. Got out of that situation and brought it home. Got to checking it over and I see the case gasket has expanded all around the bottom of the cylinder like loose head bolts and nuts or excessive crankcase pressure.
gasket fail.jpg
gasket fail.jpg
The gasket is even split at the corner. The head was torqued 3 times in 48 hours. The 3rd time nothing moved. I called it good till first heat. First heat was about 7 miles but I elected to take it further. Hind sight is 20-20. I know the breather is clear! Athena gaskets. I read over there some place they were suspect but I'm having trouble getting my head around this. Will re torque in the AM when engine is dead cold. Any thoughts? Anybody have this problem? Thanks
Thu
 
Any thoughts? Anybody have this problem? Thanks
I don't know for a fact... but I suspect mine crept out a bit during the first few hrs and torques. I thought it was my imagination but maybe it wasn't... Not as bad as yours though. Bottom line, if it ain't leaking, I wouldn't sweat it.
 
I don't know for a fact... but I suspect mine crept out a bit during the first few hrs and torques. I thought it was my imagination but maybe it wasn't... Not as bad as yours though. Bottom line, if it ain't leaking, I wouldn't sweat it.

Roger that Jim. Will re-torque in the AM and try it. Thanks much!
PS, I used a cometic gasket on both side case covers. Wish I had of had one in place of this one. Best gaskets I have ever used.
Thu
 
Wow 5Twins! Worse than mine. I feel a lot better. Was it you that said you had a copper head gasket? Wonder if they make a copper gasket for this area? I think Cometic will make a one-off. I might shoot them an e-mail and ask. Might come in handy for later. Thanks 5Twins.
Thu
 
No, no copper head gasket, just an Athena one (which has failed on me unfortunately). On the base gasket, I even put sealer on it, as you can see by the dark areas coming out from the joint. Here it is after I trimmed it off. It hasn't given me any further issues. It came out so far and stopped.

6KaU0FK.jpg
 
I recall, or is it my imagination, the Haynes manual said to put the gasket on dry. I always assumed it went on dry so the cylinders could be easily separated from the crank case later on. But maybe it is to prevent the gasket moving with time. But then what is moving it, crank pressure???
 
I don't know if the gasket sealer I applied made mine push out but thuban's appears to be dry? Yes, some of the new base gaskets do have factory applied heat activated sealer on them. Originals seem to have some applied along the front and back as well (slightly darker areas) .....

iO94aI7.jpg
 
:popcorn:Is anybody able to physically compare the Athena base gasket directly with a Yamaha base gasket ?
It seems too likely that the Athena gasket is bigger to begin with. It would be natural to push the gasket edges in during assembly for appearance ?
Athena Corp is a large very reputable company but just maybe there is a design error.
Looks really bad. I would be very disappointed if it were to happen.
-R
 
Yes, many of the Athena 650 gaskets seem to be slightly over-sized. This one scared me when it pushed out like that, but like I said, it stopped coming out any more and has never leaked. After I trimmed it, it looked fine and never pushed out more.
 
5Twins, I do see folks putting grease on gaskets (like the side cases) so they can take them on and off. The grease keeps the gasket from sticking. ( The thing about always having the mating surfaces clean (so the gaskets will stick!) Ok, I can see that for case gaskets.
That aside, ( Yep, Paul) head gaskets do go on dry and ( Yep, Kevski) they are designed to stick with heat. ( Clean surfaces) Removal is a lot of gasket mating surface scraping going on.
But, this bike is new to me and training on other equipment, aircraft or whatever don't cut it where people with hundreds of years combined experience on these on these bikes weigh in. I sprayed "Permatex" Copper Coat on my head gasket AND on my cylinder to case gasket. I should have put the case gasket on dry or used Yama bond #4 if I wanted to be sure. But, the Athena gaskets look, feel and torque like they have a lot of "Flow". Evidently they do, IF they don't stick in place.
The gasket is being pounded out, not squished out. Combination of the applied torque to the cylinder studs, mainly, rebounding against the stretch of those long head studs due to compression. No different than spark knock, detonation, on an auto, lifting the head and the head bolts pulling it back down on it's gasket and block creating a ping or knock. ( That's how the heads gets cracked) But I don't know.

I retorqued this morning and a got a bit more. Could be the squishing of the gasket? But the head gasket is holding fine so far. 5Twins, how many miles you have on the head gasket? And also if you please, If I were to set my timing ( I F I ) at the rear mark, right hand mark here, wear on the timing chain would tend to advance the timing to the left getting better and better until it fell out of time on the advanced side ? True? Thanks
Thu
 
:popcorn:Is anybody able to physically compare the Athena base gasket directly with a Yamaha base gasket ?
It seems too likely that the Athena gasket is bigger to begin with. It would be natural to push the gasket edges in during assembly for appearance ?
Athena Corp is a large very reputable company but just maybe there is a design error.
Looks really bad. I would be very disappointed if it were to happen.
-R
Jim's did the same thing but no leaking and no problems. I think it was my error and not the gasket. But as I said up there, the Cometic gaskets on my side cases are outstanding, non-stick and reusable. Stainless with Viton on both sides seals without sticking.
Thu
 
I use Permatex copper spray on the head gasket, everything else gets Permatex aviation sealer. It's pretty much all I've ever used. Cars, aircraft engines, bikes... whatever. It doesn't harden so it's (relatively) easy to remove parts without destroying gaskets. And other than the odd screwup on my part ( :er: ), I've never had leaks.
My base gasket isn't terribly noticeable. I could trim it... and might do so this winter, but it's not really high on the list.
 
I don't have a whole lot of miles on the gasket (maybe about 12K) but quite a bit of time (about 12 years) and mostly short runs. It's been put through lots of heat cycles. Spraying them with that copper gasket sealer is what many of us are doing now. Back when I did this one, I used a little Yamabond in specific spots. I'm thinking that spraying the whole thing may be better. I will use a different brand head gasket when I fix it, a Vesrah probably. But, it's also possible that eventual leaking head gaskets are just one of this bike's quirks. Many untouched originals have them, but I realize that is mostly due to the heads never being re-torqued. I consider it a required maintenance item on this motor. But, even though I did that, mine still gave out. This was my 1st 650 so I have no others to compare it to, but like I said, maybe it's kinda normal for this motor. Maybe it's just tough on head gaskets. The '83 I recently acquired supposedly had the topend redone not too many miles ago, so that head gasket should be pretty fresh. I think it's an Athena too. It will be interesting to see how it holds up. So far it's good but I haven't run up a ton of miles yet, only about 500.

As far as your timing question goes, no, I think the opposite happens. As the chain wears and stretches, the length of the front run between the cam and crank increases slightly. This would fire the points later, which means the timing would be more retarded. You compensate for this by advancing the timing setting, rotating the points plate clockwise, against the counterclockwise rotation direction of the cam. This makes the points cam contact and open the points sooner which advances the timing. Once the chain stretches too much, you run out of adjustment slot on the points plate and can no longer compensate for the chain wear. This is one of the indications that it's time to replace the chain.

But, many of us feel it is a good idea to set the timing a few degrees retarded, over at the right side of the F "range". It wards off pinging and I also think the bike performs a bit better at higher RPMs and speeds. I originally retarded mine a little to cure some minor pinging I was getting on hot days. The bit better performance was an added bonus I discovered afterward.
 
I’ve only set points timing on 3 XS’s all stock 78’s & 79. Using the timing light as a final confirmation of course there can be discrepancy between the Lft (1) and Rt (2) cylinders. Hard to get them both perfect is what I’ve found so balancing out the difference by rotating or slightly moving the point plate has worked to find an acceptable balance.
Can be a little frustrating.
Does this seem acceptable practice ?
(or advice) ?
-R
 
Yes, setting these dual points and the timing can be a chore. It's basically two separate little ignition systems, one for each cylinder. Not only do you have to gap the points and set the timing on each one, then you need to try and match those settings cylinder to cylinder. Some don't consider the points gap too critical but I like to get it as close as possible to the spec. To do that, I use a dwell meter. This electronically measures the points gap and eliminates the possibility of feeler gauge errors. I set the points at the large end of their gap spec because they usually wear closed over time. I figure this way, they'll remain in spec longer. Then it's on to timing and matching it cylinder to cylinder. Yes, that can be a trying experience, lol. I've thrown the towel in sometimes, coming back to it a few days later to have another go. Another thing I'll mention is sometimes it's impossible with used points. They're a maintenance item and require replacement about every 10 to 15K miles. I recommend that on a new-to-you points equipped bike, you start with fresh ones, if not immediately then shortly after you get it running. Put them at the top of your "to do" list.
 
I use Permatex copper spray on the head gasket, everything else gets Permatex aviation sealer.
There he is! I was waiting for you to chime in, pal. I was able to find both at my local auto parts (never any parts available) store, for cheap(!)
"The Basketcase" is slow going (it's a budget thing...complicated), but the motor will go back together using these sealants. :thumbsup:
 
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