Dreaded rocker box leak

[Truckedup]

There been many discussions on it..My recent A10 build had a persistent leak... Tried everything, different rocker box, copper gaskets and a variety of sealers that worked well on other engines. Some thought the crakcase breather was at fault...I even made the rubber bushing top mount....
 But I finally fixed it. I bought a gasket material from McMaster-Carr online industrial supplier...Palmetto #2970 Supersheat, aramid fibers bonded with nitrile, .031" thickness. Rated for 700F degrees at 1000 psi...about 15 bucks for a 18 x 18 sheet...cuts easily with sharp scissors or blade...
 A few rides, no seeping.......as of yet, lol...

[Topdad]

Can be a bloody nuisance , on my first A10 it drove me mad and only ever cured it when a mate who had very long fingers popped the pushrods home without using a comb ,once I even got it dry when using home cut cardboard gaskets ,how the hell he did it I'll never know !

[Rocket Racer]

That does sound like an excellent product. I'm using the SRM one piece combination gaskets which are fairly good and simplify assembly as they stay in place, they do compress from use so need to be retightened to control weep.
I had no joy with trying copper, The process isnt helped by the comb negating the option of sealants on the back section of the rocker box and the rocker boxes have a narrow joint face as well.

[chaterlea25]

Hi All,
On the last few engines I have put together I did not bother with the comb
Hook opposite rockers up with rubber bands, a good LED torch and a "hookey" bit of wire , Job done

John

[Minto]

Hi All,
On the last few engines I have put together I did not bother with the comb
Hook opposite rockers up with rubber bands, a good LED torch and a "hookey" bit of wire , Job done

John

And if it’s a plunger, take the seat off. A dentists swivelly mirror is handy too.

[Greybeard]

My method for those pesky pushy rods: open all the adjusters fully. Hold the rocker arms up, (cups held down) with lacky bands. Wind the end of a length of soft gardening wire around each push rod. As you lower the box, manouvre the wires to get the rods in the cups. A bright torch helps. When the rods are all located pull the wires out then tighten down the box. As the adjusters are fully out, the pushrods can drop out of the cup, so cut the elastic bands and pull them out after you've set the valve gaps.

On my Plungie the saddle needs to be off to get the tank off.

[Minto]

On my Plungie the saddle needs to be off to get the tank off.

GB, is your seat as much a pain in the rear to remove as mine? Undoing the bottom spring bolts through the springs 1/4 turn at a time, or have you devised a shrewd and cunning modification?

[Rex]

Not a mod as such, but I always make sure those seat spring threads are  free-running, then you can crack the nuts with a  spanner and spin them off with a small-bladed screwdriver through the coils.

[Greybeard]

GB, is your seat as much a pain in the rear to remove as mine? Undoing the bottom spring bolts through the springs 1/4 turn at a time, or have you devised a shrewd and cunning modification?

My saddle fixings are home brewed. I undo the top bolts and leave the springs attached to the frame. The tricky bit for me is undoing the plate under the saddle that is hinged to the frame.

[TT John]

I thought I had a bad rocker box leak also, after a reasonable ride there was oil all over the head. determined to solve the problem, when I got back home, I let the bike cool down, I cleaned off all the oil using a brake and clutch cleaning fluid, under pressure, I then started the bike up and allowed it to run for about 5 minutes, I then noticed that the oil was coming from the pipe out of the crank case, it was only a short piece but blasting it out forward, so I can only assume that the oil was spraying from there and as I was going along being thrown back onto the engine.
I looked in all my books and could not find any mention of this pipe, no illustration in any of them.
So just have a good check before thinking the rocker box is leaking, it may not be that, remember a little spot of oil can travel a long way on a hot surface.

Regards TTJohn

[Swarfcut]

  TT.. The only pipe I can think of on a standard engine is the breather, and this exits over the gearbox sprocket, pointing backwards. So either I've missed something or is there is an additional pipe somewhere ?

 Swarfy.

[TT John]

Swarfy,
That's the one, mine was  secured to the front stud and just a short piece was showing and it was facing forward, hence what was happening was oil was being sprayed forward and the air flow on the move was enough to make it look like I had a very leaky rocker box and as I didn't want it on the tyre I stuck a hose on it going, to the back mudguard.
I would hate to think that one of my solid copper gasket rocker box kits was leaking, engine clean as a whistle now.

[RDfella]

Yes, but ..... Unless you're starting the engine when wet-sumped, shouldn't be throwing oil out of the breather.

[Richard Hinton]

refitting rocker box, i always put a bit of grease into cups then the push rods stay in the cup. even if you move the rocker arm up or down when it gets hot the grease disappears. might be use full tip.