Cylinder to case gasket fail

5Twins, Outstanding on the point advance question. I have mine retarded a bit. I see the bike loads up the plugs when idling but burns perfect at speed.
I set/ check my dwell @ 22.5. (or set gaps to .012 to .016, I used .012 with the new chain to get point plate to fall in. It was Jim or you that said to try a smaller setting?) Check the timing chain adjuster. I pull the plugs and rotate the right cylinder CCW coming up on compression stroke.
I ground one lead of my test light and the other lead to right Cylinder points. Turn on the ignition. I rotate the engine CCW until the timing mark hits center of the "F" and the light just lights. If it doesn't light, I loosen the two point plate screws ( big ones ) and turn the whole plate till it does. Lock it down, rotate the engine, using the Alt nut, CW till the light goes out. The rotate back CCW and the light should come on at center "F". IF good, rotate engine 1 turn to put #2 cylinder coming up on compression. Switch the test light lead to bottom point set and rotate engine CCW to bring the mark to middle of the "F". If light doesn't light, with timing mark @ "F" , loosen the right and left bottom point plate screws and nudge the plate till the light just comes on. Lock down the plate, rotate the engine CW till the light goes out and then CCW till the light just comes on when timing mark hits middle of "F". If your advance unit is good, when you check it with a timing light both Cylinders will be dead on center of the "F". You always want to back off CW on the crankshaft and come back to the mark CCW to keep the timing chain taught. This is what makes this method accurate. Easy but hard to type out!
Thu
 
Uh, re. most manufacturers' ignition advance specs being a tad too much so, credit Gordon Jennings. If you don't think raising the deck .017" is significant, I guess you'll like those Athena head gaskets. I prefer Vesrah gaskets, made in Japan to OE specs. I used a copper head gasket from Cometic in my current motor. Other sources for head gaskets include Ottoco and Copper Gaskets Unlimited. +1 re. Permatex copper gasket spray; I've used it for many years with no regrets.
 
Athena, Vesrah, Cometic, are there no Yamaha Corp gaskets still available ?
I would as well want the thickness and deck height as close to stock as possible. Especially for the remaining bikes with points ignition.
I have a nice extra top end sitting and am watching. Maybe it’s time to go to the local Yamaha shop again and order.. -RT
 
Actually seriously asking why so many members are using these gaskets manufactured by other brands. Is it the price ? Convenience of online? Quality? The green color perhaps? Lol..
 
Gaskets are pretty expensive from Yamaha, so yes, I guess price is a big factor in going aftermarket. The convenience and cost savings of a complete kit also is a factor. I get my gaskets mostly from eBay now. I look up the Yamaha prices and comparison shop. Good deals can be had and I've laid in a pretty good supply of all I may need (oil filters, both side covers, carb float bowls, points/advance housings). I look for originals mostly but have nothing against some of the aftermarket ones. I was able to score some Vesrah topend kits quite cheap. I do like the Athena sump filter gasket and think it holds up better through multiple uses than an original.
 
All right ;)
Thanks, I have not yet ever rebuilt an XS650. Just maintenance. In the past I did rebuild a couple Yamaha engines and trannys. (XJ650RJ and FJ1200)
and used only Yamaha gaskets. And of course many Honda 2 strokes, Yamaha YZ, Suzuki thumper, etc. I’ve just always gone to the bike shop and ordered OEM because I only do this sort of thing occasionally.

I am very likely to buy a Yamaha top end gasket set Friday at the local Yamaha dealer just to have on hand. This sort of visit is part of the entertainment for me still. I realize many members do not live near a motorcycle shop they enjoy to go visit.
Thx -RT
 
I thought I'd just throw this in here. This is a pix of the head I replaced. It was a new build with a total of 40 miles on it at speeds less than 45 MPH. It had an Athena gasket that I rather liked the look of. I sprayed the gasket with Coper Coat. You can see where the copper transferred from the gasket to the head. You can also see where the material from the head gasket started to stick to the head in places. The 40 miles were many small jaunts and the engine never got good and hot. You can tell a lot of oil was getting past the rings but it didn't smoke.
head gasket.jpg
 
Be prepared for "sticker shock" if you go to the Yamaha dealer for gaskets. They get more than $50 for just the head gasket, $15 to $20 for a base gasket. Those big red o-rings around the bottom of the cylinders are $8 each. So I guess you can see the appeal of a complete aftermarket set that contains gaskets for the whole motor, usually o-rings too, for $50 or less.
 
Those big red o-rings around the bottom of the cylinders are $8 each.

So I guess you can see the appeal of a complete aftermarket set that contains gaskets for the whole motor, usually o-rings too, for $50 or less.
Yes, the sad truth will likely be too much to take unfortunately.
 
I've used the green Athena gaskets on my left engine casecover. Don't like them. Green, for one thing, sticks out for another. Compared to normal black gaskets, I found the Athena gasket to be squeezy/oozy. There's a thin zone at the lower dowel hole, and the gaskets would eventually just ooze outta there. I suppose that if you need something squeezy/oozy compliant, like for a rough surface, the Athena is the one.
 
I have used the Athena a few winters ago when I replaced the cam chain and guide. I wiped on a thin coat of oil with my finger on boths sides even before I had read it was to go on dry :doh: . I do this on all the other gaskets but was nervous about the whole 1st time engine open will it run again and was not paying attention. I installed and it has never leaked for me. Yamabond grey was used on the head gasket and cover. No leaks to report and has had 1596 kms so far with 150psi in both cylinders. Did not re-torque since the initial one.

*edit* initial torque was set in 3 increments to a max of 32ft lbs for acorns. All others set to factory specs.
 
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very interesting thread . Gasket treatment preferred choice and recommendation seem to be closely allied to owners current or previous work experience . ie aircraft maintenance and repair or auto repair etc .
Something that directly effects gasket sealing efficiency that has not been mentioned yet and is probably overlooked on many engine rebuilds is resurfacing and truing of the gasket surfaces . Repeated re-torquing stretches bolts but the bolts can also create a slight raising of the gasket surface around stud and bolt holes which need to be dressed back when rebuilding .

Looking at the head I was rather alarmed to see that a couple of the fixing holes on the head have little if any gasket surface between the cylinder and cylinder head fixing holes . These areas would rely completely on the integrity of the gasket and my guess is that compression gases would eventually leak into the head bolt holes and potentially leak past the acorn nuts and washers. presumably why thick copper washers are recommended for the 4x head bolts

Looking at the edges of the holes the chattering on the aluminium looks like someone has taken a deburring drill to them which has seriously reduced the gasket surface area around a couple of the holes.
xs650 head.jpg
 
I picked up a couple of those as well, except they're for the XS2 and later motors (larger head gasket). They look like nice gaskets, made in Japan, and you can't beat the price .....

9sfUVBp.jpg


I also scored a couple Vesrah kits for about the same price. I'll probably try one of these next .....

epxorvM.jpg
 
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