ANLAF'S THIRD REBUILD DISASTER with VIDEO

Once you have everything you need, tools-wise, and all those little extras, sealant, lapping paste, beer, etc, then you will be able to walk on rice paper without leaving a mark. I want to get to the point of not spending money on peripherals - I am hoping I don't have to spend on valve guides.

Anlaf
 
ANLAF everyone will have an opinion on what stuff to use on your headgasket and perhaps it does work. I have two tubes of now banned substances Yamabond 5S from the 70's and Threebond 1194 that I bought earlier this year. However that stuff is normally not recommended for higher temperatures like a head gasket. I have two original Yamaha headgaskets from the 70's and they have the same sealant factory applied material as shown in the earlier pictures. Some will say that headgaskets from the 70's likely were made containing asbestos and other deleterious materials and using headgasket sealant that was readily available for cars at that time and applied with a round dauber was fairly common. Permatex made such a product in the 70's and called it headgasket sealant that went on more like glue than gasket maker stuff. Permatex stuff reminded me of the shiny stuff shown in those original headgasket pictures from Yamaha. Today the new material and fancy methods for cars has imbedded goo around problem spots. But not so with the aftermarket headgaskets that you may be buying. Read the temperature and application limits on the sealant you want to use and apply it with a very small brush - almost like a women's eyeliner as you want just a skim. If Yamabond #4 works that is great as it is readily available in your toolkit. However if you were starting over from scratch I think you should choose the higher temperature rating of the Permatex aviation Form-A-Gasket or similar type stuff. None of this stuff will overcome warping so that should be the first check with bluing, light lap to see your low spots. If uncomfortable with results, lap it or take it to a known engine builder for a fly cut. Retorque more than once and fairly quickly the second time once warmed up. The first fog out of an engine could just be moisture in your exhaust system.
 
Sequim, thanks. I am going to use the ThreeBond when it gets here. I will follow the recommended application to the head gasket. I am convinced that my trouble was oil getting in the head gasket from the cam chain channel, and my video has got strong evidence of that. I don't want to use silcon (potential damage to the engine) and the Threebond and Permatex fit the bill.

The excitement is unbearable, eh! I am sat here, adjusting brakes, and looking at the tops of the pistons waiting for the ThreeBond to get here.Thanks for your contribution.

Anlaf
 
Thanks, TwoMany - but I'll have to hide the 'Guru', I can't quite walk on the rice paper without leaving a mark yet.

I think I have to find something in the control panel.

Anlaf
 
ANLAF, just thinking which could be dangerous this rainy morning, but go very slow on your head torqueing. Consider that the leakage is in the middle of the head not the edges. Spread your head by torqueing the middle area in a cross fashion just a few say 10 ft-lbs up each time before moving to the edges to ensure you are spreading the head and not torqueing the edges first, then the now restrained center. Just take your time on this final step.
 
Same logic applies to bad/worn rings and cylinder. There's periods of hi-pressure and periods of low-pressure. The oil either gets sucked in, or the blowby goes into the crankcase, to be vented out the crankcase breather. Doesn't take much for oil to get in there, even happens on worn rings in fresh cylinder, upside-down rings, fresh rings in worn cylinder, fresh rings not properly seated, ...etc....

Rings normally pass both oil and combustion gasses in manageable amounts. Head gaskets do not.

How does the head gasket readily leak oil inward enough to foul the plug without also leaking highly pressurized(1000+ psi) combustion gasses outward?

Ken
 
Oh, it will. Goes out the crankcase vent, just like blowby. Usually max combustion pressure is around 800 psi, full throttle, but drops to 60-80 around idle, but it has to push oil in the slip/gap outta the way first, takes time. Leakdown tests can reveal headgasket leaks, helpful if you can probe around it with a hose jammed in your ear. Worst case, of course, is the complete burnout/blowout of the headgasket crush ring. In this particular scenario, however, the oil infiltration has been hampering ignition, so his engine hasn't been able to stress the suspected leak zone...

Also, as the piston travels down, the cylinder pressure drops, but there is also a complementary momentary increase in crankcase pressure from the displacement of the backside of both pistons, before it gets vented. Aids in shoving oil in there...
 
Anlaf - another idea..... are the liners secure and sound in the cylinders :confused: if they're a bit loose (as when running & hot) or not well fit in the block this can cause problems..... :doh:

Just a thought.... hopefully the cam tunnel goo will fix it. this is very common on the old Z900/1000's.... and the cam tunnel "O" rings cause endless hassles.... Copper/orange Hi-Temp Permatex (or whatever its called) is the favourite goo :thumbsup:

Watching with bated breath (must go see the dentist)....
 
Pigford, I like your thinking, but I can say without hesitation that is not the source of the problem - why? because I have swapped the original cylinders for re-bored cylinders, for cylinders re-bored to matching pistons and rings.

This ThreeBond is taking its time getting here.

Anlaf
 
I like the description, TwoMany - my head still hurts from your detailed explanation of the usefulness of the power brake valve and the vacuum effect deep inside the workings of the engine.

It makes sense that the breather would dispel pressure that might otherwise find its way through the head gasket at, what was it, 800 psi. Useful things those breathers, and I've managed to find one of the later single vented breathers - the bore of that is much smaller, too.

Anlaf
 
But I have not been wasting my time, I worked on engine two, managed to remove the knackered started/idler gear - everything working perfectly now - gave it some gears (the shifter-shaft way out of adjustment), put the clutch back and cleaned up the casings - now the top-end, and if anyone can do a top-end blindfold it is I. I need some exhausts for engine 2 - saw some rusty old headers on eBay a few weeks back, but they wanted £50. Then I can do a Hughs Handbuilt type start-up with the engine on the stand.

Anlaf
 
Back
Top