#7 joins the fleet

[MikeScoot]

The idea is that as the clamp is tightened the space occupied by the gasket reduces, thereby forcing the gasket material hard against the surfaces that constrain/contain it. A couple of exhaust fellas explained to me that this system is the very best for getting a very tight exhaust gas seal - but I think it assumes the correct gasket being used. Filling the volume around the gasket with high-temp silicone and leaving the assembled pieces only "finger tight" till the silicone sets a bit, then tightening a bit more, then leaving a while before a final tightening seems to have workd for me - BUT I haven't taken th bike for a long run yet as other things have come up.

Good luck with it! Those gaskets you bought may not be a waste at all!

[Prophet Of Doom]

Some more progress.  All the pipes are connected, and wiring as well.
Very pleasingly everything worked first time - a testament to the virtues of fanatical cleaning.

[MikeScoot]

ExZellent!

I've been having a bit of a clean around here too, but not quite the required fanatical type yet. I've got XZ leftovers EVERYWHERE and more half-expired spray cans than you could poke a stick at! Funny about that 'cos I'm seriously thinking of stripping all the paint I did (which took a good few months and sheetloads of bucks) to do and giving it another simple job in two-pac.
Acrylic really sucks!

Hope you're enjoying the summer there!

[fret not]

Oh my!  That is a vision to behold!  Lights!  It causes me to consider my project and when I might see the lights come on.  For me it will be like stumbling onto a derelict space ship in some remote and desolate place and to find there IS life in the old system after all.  It's magic.

[Prophet Of Doom]

I took a closer look at the Y-piece.  To the aging naked eye it looks fine, but it's actually fairly eroded around the copper o-ring.  Hence the sloppy ring.
I've painted it with hardening type exhaust gasket goop.  I'll let it harden and cure, then file it.  Lets see if that takes out the o-ring slop.

[fret not]

Looks like peanut butter putty.

[Prophet Of Doom]

The rings are now a tight press fit.  Not sure if it will hold up, it's pretty fragile.

[Prophet Of Doom]

Well it didn't hold up.  A complete fail.  I ended up taking it all off with a wire brush.

I have a small (disposable tanks) Oxy/Propane torch, so brazed a layer of silicon bronze to fill the flame cutting.  The Y-pipe is a bit heavy for this tiny torch - it only just managed to get the pipe hot enough to melt the bronze.

The Y-pipe seems solid enough now.  I still think a decent flange would have been more sensible Mr Yamaha.  I forgot to take a pic of the Y-pipe, and it's too late now.

[MikeScoot]

Can't see much at all of that pesky "Y-piece" in that pic, but what I do see looks very nice indeed!
I think the trick with the "Y-piece' is to have enough material inside the cavity of the clamps (and at the right viscosity or size) so that when the clamps are tightened they force the material hard against the pipe attached to the head.
The arrangement is a prime feck-up - from a serviceability point of view!

[Prophet Of Doom]

Bled my brakes today to make the bike safer to take down from the lift. 
I am reminded that the bleeding procedure outlined in Haynes and the Yamaha service manual is OK for fluid changes, but does not work well if you have new empty lines and calipers.

The process I use is to pump it up from the bottom with a syringe.    This one's a bit small but all I could find on a Saturday.
When re-loading the syringe, you need to pull back a bit to get any bubbles out before pumping.  Go slowly else the fluid comes out the master cylinder like a fountain.

Love my Hell braided stainless lines.  Lever action is solid as a rock.

[Prophet Of Doom]

Hmmm, that's not a good sign.

[fret not]

Rohan, did the O ring fail?

[vintage bikeworks]

Hmmm, that's not a good sign.

Is that engine coolant?  Not from the water pump cover o-ring I hope? 

[Prophet Of Doom]

Hmmm, that's not a good sign.

Is that engine coolant?  Not from the water pump cover o-ring I hope? 

No but that would be an easy fix.  It's coolant coming from the head gasket.
New gasket, clean surfaces and properly torqued to spec. 


Warpage, piece of debris, a crack? Won't know till I drop the engine and crack it open.  Again.  Sigh!

[fret not]

Things like this teach us about patience.  Has this motor been run since you installed the head gasket? 

[MikeScoot]

Don't race into pulling the mill down too quickly. Coolant circulates independnt of the combustion components. It could be a simple small crack somewhere or those pesky tubes from the pump to the motor.
Leave it alone for a day or so and have a good think, mate. There may well be a very easy fix.

[Prophet Of Doom]

I'm looking to reproduce the miscellaneous decals that came on the bike from factory.  I'm sorted for tank decals and switchgear but need things like oil labels, tyre sizes, check brake linings etc.   
I don't even know what came originally.  Does anyone have any photos of these?

Meantime, the engine is back on the bench so I can address the coolant leak.  The surfaces were well cleaned and bolts torqued to spec.  I figure something is preventing the torque being properly applied to the mating surfaces.
Working theories are
a) the stud bolts have backed out while unscrewing so the cylinder nuts are bottoming out
b) the drilling depth on the heads changed at some point and the cylinder nuts (from a different bike) are bottoming out
c) the dowel pins have got on a jaunty angle and prevent the head from fully torquing down
b) the cylinders / heads have warped and prevent the head from fully torquing down

[Walt_M.]

Hi Rohan
 Happy Boxing day. Thinking about your problem, have you thought about using new nuts? The threads could be failing and causing you not to be able to reach torque spec.

[Prophet Of Doom]

Hi Rohan
Happy Boxing day. Thinking about your problem, have you thought about using new nuts? The threads could be failing and causing you not to be able to reach torque spec.

Thanks Walt, Happy Boxing Day to you too.
At this point I've eliminated the nuts - I am getting good torque readings and the threads are in perfect condition

The engine is a 16R, the cylinders and heads are from a 11U.

Starting with the front cylinder (which was leaking a lot more than the other):

d) Check flatness of the mating surfaces.  I taped some 400 grit to my surface plate (certified flat to 0.0001") Some back/forth action and I can see that these are far from flat.  Almost the entire surface is one giant high spot.  About 3000+ strokes later and it's looking freshly machined.  Still a few casting defects, but trying to catch them could reveal more, and I don't want to mess up clearances.  Very little warpage evident on the cylinder, but cleaned it up anyway

c) The dowel pins look good.  Slight corrosion only.  Double checked the recesses were clean and polished the pins to a shine.  With a liberal coat of assembly lube they slip in easily, but not sloppy. Tapped gently with a rubber hammer during assembly to ensure good seating.

b) There is no significant difference between the 11U and 16R drillings.

a) The studs sit 2mm higher on the 16R than the 11U engine.  If I'm less than 5mm from the top of the stud to top of the nut, then I'm bottoming out.  I'll torque and measure that tomorrow and move on to the rear.

[Prophet Of Doom]

Everything back together and I blew some air in to check it was now water tight.
Depressingly it's still leaking out the head gasket.


Take care to to use too much pressure.  15PSI is about right