FH - rocker box

It's pouring with rain here today so badly that I can barely take the dogs out, so I've taken a little while to come and varnish an oak window sill and fit the rocker box to the Huntmaster. 

We start with Wellseal on the rocker box gasket faces and stick the gaskets in place. Next we'll put another coat on the cylinder head gasket faces and manoeuvre the rocker box into place over the pushrods.

I'm using a small USB camera connected to my phone to have a look in some of the small spaces around the top of the engine. The camera is small enough to go down towards the pushrod tunnels so that we can verify that the bottom end of the push rods are sitting in the tappets properly.

The camera fits through the inspection hole in the top of the rocker box and through the big spaces at the front and back to allow us to see whether the push rods are engaging with the rockers properly. You can get a small screwdriver in front or rear to nudge the pushrods into place.

With a bit of fiddling, I got the rocker box down and bolted. These bolts are actually supposed to have shakeproof washers so I shall have to change them later but the gaskets are pulled down properly. I've also fitted the rocker box oil lines.

So this all went pretty well except for one thing. Whilst the rocker box is down and I've managed to adjust the exhaust rockers to a reasonable clearance, there is no way that I can get the adjusters far enough into the rockers to bring the inlet rocker clearance to specification. I'm not sure what's wrong with this, it might be worn adjusters, it might be worn pushrods...

Wish I had had the foresight to measure the pushrods before I started...

Bond of Brothers

Hermetite... Hylomar... Yamabond... Wellseal... Hondabond... B&Q Bathroom sealant????

So many choices - but which one?

In the old days, in these situations I used to use traditional Red Hermetite or more recently Wellseal. I've also use blue Hylomar in the past. Usually the selection is made on the grounds of availability - what I had in the toolbox at the time.

I've no real engineering information for any of these products, and have never made a proper assessment of them.

However, for the SQ4 I wanted to look at a modern sealant. I hope to avoid tearing the engine down again anytime soon and with the legendary folk tales of excessive engine temperature (300 F at the plugs) I wanted to make sure I had something which was:

• suitably rated for temperature 
• compatible with engine oil 
• compatible with aluminium 
• a suitable colour (i.e. not red & smeared all over the cases!)

Several books and web forums I have read, both bike & car related (& even stationary engines!) mentioned Threebond products, Yamabond & Hondabond. Now, a quick Google reveals that Yamabond & Hondabond are both rebranded Threebond products.

Threebond describes itself as a fine chemical technology company with its roots in the automotive industry. Apparently, more than 90% of the world's motorcycles are assembled using Threebond products. Probably worth a look then!

Threebond say:

1200 Series silicone-based liquid gasket fills gaps on a flange surface and thus completely prevent leaks. When cured, it forms an excellent rubber-like elastic body offering excellent resistance to vibration and shock. Also it has an excellent resistance to heat, and effectively seals joints that are subjected to high temperature.

Here's the specification for Threebond 1207B:

• Excellent chemical resistance against coolants and engine oil 
• Outstanding mechanical and thermal resistance 
• Excellent adhesion even to slightly contaminated surfaces 
• Extremely fast curing 
• Instantaneous impermeability for pressure- and fire test. 
• Acceleration of the curing process by heat and contact with the medium 
• No shrinkage and no generation of corrosive gases 
• No corrosion of metal and only very slight reaction on plastics 
• Normal disassembly

Here are the material properties:

 I now have a tube of this. It has a Honda label & part number!