While waiting for my garage to be completed, I'm planning out the steps on my 1980 FXS-80 project. The engine runs rather well but, as you'd expect, leaks oil. I'm still diagnosing all the leak points but there are definitely leaks around the rocker box bolts on the front cylinder. And also around the front rocker box to cylinder head joint. Interestingly, I don't think I have any leaks between the jugs on either cylinder. So I'm thinking of pulling the rocker boxes off and cleaning them up, putting on new gaskets and properly torquing them.

Can I get the rocker boxes off without removing the whole engine from the frame? And also without splitting the jugs? At some point I'll split the jugs and do work on the rings and such, but I'm trying to do this job in smaller "pieces".

I'd like to strip the boxes of the bad, flaking paint job a prev owner did. (See pic).



Is there anything else I should be doing while I have them off - like valve work or remachining of the rocker box/cylinder mating face? I'm mostly concerned about the interface being crisp, since the whole point of this is to address an oil leak on an otherwise good-working engine.

 

 

You need to take of the heads in order to get at the rocker boxes. Not necessary to pull the engine.

Just make sure you have both pistons at the low point and you don't how to worry about pistons and rings. Basically it's just tanks, carb and manifold, upper motot mount and pushrods to get at the heads

 

Thanks. Whether or not I needed to take off the heads is what I was wondering. I really didn't want to, because there's no leak coming from the interface with the heads and the lower cylinders. But, if I have to, I have to.

And that answers the question about the head and rocker box interface. I suppose while I have them both off, I can inspect them and machine them if necessary, before putting in a new gasket and reinstalling.

 

have the rocker boxes fly cut flat it will save you doing this job again soon as the heat and years of service gets the alloy memory back in check

if they did use washers at some point and the stud hole tops look chewed then have them spotted as well so the torque is correct across the entire cover

 

Also check the studs to see if any are pulling out of the heads, lotta guys go gorilla trying to stop the leaks and pull the studs out.

 

If you are pulling the heads and you don't know when the top end was gone through last, you might as well pull the cylinders too. This way you can get a look at the pistons, rings and wrist pins and refresh if needed. You can also get an idea on condition of the rod bearings.

 

Well crap. You're right, of course. I bought this bike to do exactly that: rebuild it. But I wanted to attack it in manageable pieces. So I thought Step 1: rebuild carb. Step 2 clean tank and replace gas lines. Step 3 attack oil leaks and replace gaskets. I probably want to inspect the pistons and rings. But I thought I'd do a compression test and if ok, I could hold off going into the cylinders. I still may take that approach and postpone the cylinders for now as there's a lot more on the bike that needs work.

 

Fly cut... i know this is like milling. But what surface are you recommending i cut? The outside? Or the rocker/head interface?

 

the same place the gaskets go is the place they leak, if you take it to a machine shop use the correct terms I used to explain what you want, - fly cut and spot the nut locations and see what he says