Musky's Plunger rebuild.

[muskrat]

G'day Fellas.
Well I've been threatening to do this foe a while. Now all the others are going so to speak, it's her time.
!st surprise was the rear chain joiner link fell apart when I removed it
Lump out and on the bench. Remove G/box. Now I need a stand for the motor. 1 beer later job done.
Pull pinion with bearing separator and modify 11/16 bs socket to remove prv (used to have one).
Split cases and pull crank out. Really surprised with the little wear on the journals. Only 1/2 thou on the TS journal and 1/4 thou on the big ends. Amazing considering the flogging she gets . I'll throw in a new ts bush (0.010 and new big end shells 0.010) no grind necessary. A  new ds bearing and the bottom end will be back together in no time.
Hold the bus. Just found a few cracks in the crank case. A musky rev head problem. The through bolts into the crank case have caused a few sml cracks. Instead of a 5/16 thread I used helicoils so it was a bit weak. Now looking for a good welder to rectify. BUGGA
Stay tuned.
Cheers

[muskrat]

continued

[muskrat]

I know you want more

[Greybeard]

Those barrel through bolts do look very close the edges of the case. Is that where the cracks are?

[Greybeard]

It proves once again that as long as these engines get good lubrication they are tough old birds. When was the sludge trap last cleaned?

[berger]

musky i am pleased to see that big puller in action, i bought some and when i opened the box i thought oh dear should i be working on BIG stuff

[muskrat]

G'day GB.
The sludge trap was cleaned about 25-30 years ago. The bearings and journals are in good condition considering the flogging I've given them. I'll be pulling the plugs to have a look tonight.
Yes the studs are close to the edge (like me!). I should have tapped 5/16 straight into the case instead of going bigger for helicoils. With the racer I had those areas built up with weld inside and out. May do the same here but I don't want to loose the engine number, it has a crack that I plugged a few years ago with JBWeld.

G'day bergs.
Yes a very handy puller, that's the small one. Will also be used to remove the drive side bearing.
Cheers

[a10 gf]

Great topic, great pictures 

[chaterlea25]

Hi Musky,
The timing side main journal on the crank looks a bit ridged when I zoom in on the photo?
I think it could do with a polish up ?

John

[BagONails]

Hi Musky, Great series of pictures. Thank you.

As you know I am no expert in matters A10 but from what I have gleaned thus far in my BSA journey; as well as the sludge trap clean out I would be considering whether the conn. rods should be renewed at this point.  Is that something you are concerned about given the way you ride the thing!?

Other than that the internals certainly are looking good.  (I agree with John, if you are renewing the timing side bush I would also get the journal polished up regardless.) 

So I'm interested to know how many miles "flogging" has the old girl been subjected to and are you running an oil filter or not?

Good luck with the weld repair etc.

[muskrat]

G'day John, BON.
The TS journal isn't that bad but will get a polish and custom bush to suit. I haven't removed the bush yet to check for out of round in the case. An over and under size bush may be on the cards.
The rods will be polished and put under the microscope. The little end bushes are perfect.
The speedo never kept the mileage well but at a rough guesstamate I'd say 60,000 miles. I used 20/50 most of her life with an in line filter. When I noticed the 8thou clearance in the TS bush I've been using 40/70  with a good dose of Nulon E10.
Tonight I removed the sludge trap plugs. DS came easily but the TS was a bitch ruining 3 impact bits (note to self don't be too heavy with the center pop on the new ones). I was surprised at how little sludge there was. I'd say about 1/2 to 1/3 of a cc. One place the muck can hide is the hole under the plug of a drilling on the TS web.
I also cleaned the cases to look for cracks/damage.
Cheers

[muskrat]

Now the cracks. 

[BagONails]

Testament to modern oils, regular changes and filtration I would say.

Re. Cracks.  What a nightmare.
I don't mean to be teaching granny to suck eggs but all I can suggest would be to 'V' out the entire length of each crack and a little beyond as deep as you dare to go then TIG weld after thorough degreasing.  It would be a good idea if not essential to preheat the cases generously with Oxy before welding too.  There may be a specific filler material that is best suited to the BSA alloy which seems to be very soft and therefore very pure. I'm afraid I can't recommend anything. Wherever possible it would pay to build up the areas/internal bosses with additional weld material to strengthen things. Then I guess take the threads/inserts deeper wherever possible, use longer studs and put them in with a generous helping of red loctite.

Then face east and make another  sacrifice to the Beezer gods!

Best of luck with it all Musky

[RichardL]

Well, there's the danger of ignoring the red warning about someone having posted while you were typing. Bago's description is clear, so read here at your option.

Oh, you're having some fun now. This is just about the time you wish you'd gone to welding school. Probably not telling you anything you don't know, but it looks to me like each through-bolt hole needs thickness buildup along side of it, inside and out (not just crack filling). I could be seeing an illusion but, in the fouth photo, there is a long line that looks like a giant crack. Is it? By the way, do you have a mill to go with that beautiful lathe? Skimming the crankcase barrel seating face seems to be in the cards.

Richard L.

[RichardL]

On second thought, is that long line that looks like a crack actually a sand-casting parting line?

Richard L.