'47 XA7 280 Early engine failures

[Brandis]

It's amazing !!  A week ago, I was staring at my empty crankcase with some dismay.  It was all questions, no answers.  It's lonely being a classic Brit bike guy here in North Carolina. Harleys and rice burners. I'm a Canadian and there were a bunch of us up there, but here. . . .
So I registered with you guys, and, within hours, the loneliness and information vacuum are gone. 
You've all been fabulous.  Pages of solid info. Impossible to get parts offered. 
Thanks from the new guy. 
On another note, I got my A7 from the widow of a guy in Connecticut who claimed to sell BSA parts. He died and I went to his warehouse.  Heartbreaking.  His weirdness was to disassemble bikes down to the last nut and bolt. And heap all the magneto points together, timing side crankcase sides together, front frame halves together, etc. You could tell there were great bikes in there. But how to sort them out in my one day visit? 

[Greybeard]

...
On another note, I got my A7 from the widow of a guy in Connecticut who claimed to sell BSA parts. He died and I went to his warehouse.  Heartbreaking.  His weirdness was to disassemble bikes down to the last nut and bolt. And heap all the magneto points together, timing side crankcase sides together, front frame halves together, etc.

What a flippin eejit!

[Brandis]

What we, in this part of the world, would call a 'good old boy'.

[Swarfcut]

  What have you done with........That recent post shows what could be an example of the early "Drop Down Stand" This was quickly discontinued in favour of a more conventional stand, as if the mechanism slipped the bike fell over if parked, or ruined your married life if under way. Stand is shown in the picture above, along with the early version of the timing cover......2 screws, flat bottom. Later version has additional centre screw and dimple. Crankcase and inner timing cover castings also change to reflect this, so care needed if searching for parts.

 Frame is rigid type, and looks to have the correct rear mudguard, toolbox and original (maybe) interchangeable wheels. Front mudguard perhaps not original, but all in all a very rare example of an early survivor.  Could be the earliest on the Forum. Frame number will confirm if engine and frame are contemporary.

 Swarfy.

 

[Brandis]

That is the question.  I'm not a fan of the 'gleaming from the showroom' look.  It's a 74 year old bike.  I've had this discussion with a vintage British car friend of mine.  We looked at it together. Rear fender, toolbox and oil tank could be brought back with some painstaking stop restoration.  But the front, not so.  It would be odd to blend and, although I spent a career in the film industry, I paint parts and age them to fool a camera.  The human eye is another thing. 
I will keep the aluminium patina for sure, and I'm tempted to to go with a semigloss paint that gets a fine steel wool treatment.  I did it on a '51 Matchless G80 and it worked pretty well.
I realize that I have a certain responsibility to do it right. 
The question is, what's right.
I enclose the photo of the rear and you can se that conservation could be a possibility. 
On second thought, I think I'll do a few test patches to see if I can pull it off.

I'm told my file is too big. Sending without photo

Any experienne in this sort of thing out there?








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[Brandis]

'Divesting yourself of material goods will lead you to the path of enlightenment.'
And in my case, it leads to boredom.

I am not a slave to authenticity on all bikes.  My daily ride is a beat up 1940 M20.  I built a replica sidecar for it so that
     - I wouldn't fall over and break my 75 year old hip, and
     - So I could hide a Toyota Hilux start motor under the sidecar seat started so I wouldn't shatter some leg part.
Ya gotta have a little fun with this old stuff too.

[BSA_54A10]

Don't understand why the original crank should have proven to be difficult to dismantle; after all, the singles were similarly mounted (on a taper). In my view the original crank was a superior design. I'm inclined to believe the replacement crank was cheaper to manufacture.
Disappointing to note the article writer includes the myth regarding that con-rod oil hole. There's no way it can lubricate the cylinders - all it'll do is add friction by spraying onto the LHS of the flywheel (remember it sprays x2 at half stroke, not TDC). Which is why I place the hole facing outwards.

The steel required for a forged crank will be near double the price of the steel for a built up crank and that is before you make some very expensive dies so no not a cost cutting exercise.
Cost cutting on a crank is casting in malleable iron.

[mikeb]

Brandis - does that imply you have a hilux start motor somehow starting the m20? if so, how?

[Brandis]

Yes, I start my M20 with a Hilux start motor, attached to a 20:1 planetary reduction gear.  Then a ratchet to allow engine over run. The whole assembly slides sideways with a lever tucked beside the seat with the start button.  Obviously I had to go 12v.  And, interestingly, the engine doesn't kick over at the top of the compression stroke fast enough to trigger a magneto spark, so I converted my magneto to be just a set of points in series with a VW beetle coil. I know this sounds like vandalism, but I saved the original M20 parts so the next owner can put it right.
For some reason, my Forum connection won't let me send 2 photos at a time so I'll send the engine interface in the next post. 
I didn't have much choice if I wanted to keep riding at 75. 

[Brandis]

As promised, the M20 electric start engine interface.  A standard industrial shaft connector with a bit of grinding to allow an easy slide together.  It looks to be out of alignment but that's because the whole starter assembly pivots from a point at the back of the sidecar.  So it comes into alignment at the end of the swing.

I can't wait to hear the outrage from Forum readers.  And, yes, I'm guilty as charged.

[berger]

i love it , where there's a will there's a way

[muskrat]

G'day Bradis.
Clever boy.
Now you have to learn how to re-size photos. https://www.a7a10.net/forum/index.php?board=15.0
Cheers

[mikeb]

That's brilliant - thanks for the pics. I assume you now ride with steel capped boots?

[Brandis]

A belated follow-up question.  RDfella said in this post :
"Disappointing to note the article writer includes the myth regarding that con-rod oil hole. There's no way it can lubricate the cylinders - all it'll do is add friction by spraying onto the LHS of the flywheel (remember it sprays x2 at half stroke, not TDC). Which is why I place the hole facing outwards."

So I'm still face with the first 500 A7 engine failure question.  RDfella talks about the oil holes in the con rod.  I have steel 2 piece con rods with no oil holes in them at all.  The  undersize bearing shells have them.  How does oil get to the cylinder walls if it's not squirted from the bottom end of the rod or pumped out at the wrist pin?
It it just a splash system?  RDfella talks about 'placing' the holes.  Is that what I do? Drill my own?
Yes, you will all be greatly relieved then I'm done and you can have your weekends back.

[Swarfcut]

  Apart from the basic layout of the early and later engines sharing a common ancestor there are major differences which could explain what's going on.

 The Longstoke camshaft is lubricated solely by splash off the big ends and oil fed down the pushrod tunnel from the rocker gear. In the very early engines there was no external rocker feed, it relied on splash and mist. From the camshaft this oil is spun onto the flywheel, contributing to oil on the bores, along with oil thrown from the big ends.

 On the later design the crankcase castings feature an oil retaining trough, into which the camshaft dips, so the amount directed onto the flywheel is reduced. Well maybe, it has to drip somewhere but this could be the reason for the supposed oil starvation on the bores. The trough is fed as before from rocker drain down, but also has a spasmodic pressure fed oilway running from the PRV on later Plunger and all S/A engines. Early plunger crankcases do not have this feed, PRV blows off into the oil pump cavity. On the later engines with this feature with no blow off from the PRV, say with a hot engine, thin oil, worn bearings, the feed will be hit and miss for most of the time.

 Now we come to differing views on that con rod oil hole. Why is it there? Is it necessary? Does it work? Why is it only on one rod? Which way should it point? Why are some engines found with both rods with holes.

 So you could say the hole lubricates the bore, or aids oil flow through the crank. So why only on the drive side?

 The answer, my friends, is blowin' in the Forum Archives where it has been debated, agonised over and otherwise kicked down the road from way back.

 I'd say leave the rods as they are. All replacement shells are drilled with an oil hole to avoid the assembly error of blanking off the oil hole in the rod on the later engines with a plain shell..

 Swarfy.