The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: charles whitfield on 14.05. 2014 16:53

Title: Post big bang - Whitsend A10
Post by: charles whitfield on 14.05. 2014 16:53
Here we go guys - After the 'big bang' my mate and I finally took the bottom end apart apart (I had been putting it off frankly)
So as a trouble shared is apparently halved, I will keep you posted on progress.
More diagnostics as we got deeper in, but a bit of background here
- SRM oil end feed conversions about 12,000 - 15,000 miles ago (reputed to last 80,000 miles or so)
- New oil every season - Max 2000 miles per year
- Laid up 5 years
- Recently noticed a knocking but was sure it was clutch related
- Always ride it full on - as I believe it's not a throttle its an on off switch
So:
Cases split - Debris everywhere, but expected
Con rods off - big surprise! Timing side had run metal to metal (SRM say with the oil feed conversion you should get over 80 psi - so how could that happen?) drive side OK, but why?
Then with CHECK YOUR SLUDGE TRAP advice in mind we had a look
Nope - timing side opened up OK (and I didn't realize that a small journal crank has no tube etc in it) but it was clean apart from shavings
Then to the drive side - impact driver out to knock it loosen and then a whack - but no turn, it just pushed it down the hole!!!!
After a load of pain we managed to get it out (see photo of cross threaded/rubbish job plug)
Can I ask for the collective wisdom here - If the drive side plug was not sealing properly and allowing the oil pressure to drop, why did the bearing closest to the pump cop it?
Or, are we way off and is there something else to look for?
NOS conrods here
New pistons on their way
New push rods here
Some more big bills on their way
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 14.05. 2014 18:09
And here are some more pictures
Before
After
Carnage
Title: Re: Post big bang - Whitsend A10
Post by: duTch on 14.05. 2014 22:09

 Can't give any ideas just now, but if SRM did the conversion, I would've thought they'd use their hex socket head plugs- unless maybe they didn't exist back then (15k / 2  = 7-8yrs ?)...a bit odd
Title: Re: Post big bang - Whitsend A10
Post by: RichardL on 15.05. 2014 00:56
Are we really seeing crossthreading there or just the results of beatingnthe crap out of it? Would expect SRM to cross thread anything.
Title: Re: Post big bang - Whitsend A10
Post by: bsa-bill on 15.05. 2014 08:59
is the "cross thread" not just the result of coming through the centre punch marks, maybe could of had a bit more of them removed ?
Title: Re: Post big bang - Whitsend A10
Post by: Topdad on 15.05. 2014 11:27
My SRM conversion was done 2002/03 and def had hex plugs fitted they returned the old ones without me asking for 'em so that seems strange. BobH
Title: Re: Post big bang - Whitsend A10
Post by: metalflake11 on 15.05. 2014 17:56
If S.R.M. did it all the casings will be etched with the job number, is this the case? If so ring them and they will tell you exactly what they did, and when. Let me know.
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 15.05. 2014 18:48
Hi all
Yes, the modified timing side cover is etched P0093 and the oil pump has had SRM etched on the sealing plate- I will give them a call since I need to have the barrels reworked anyway, plus a spacer dropped out that when I split the cases (a specific bit they added) - but I didn't expect it and didn't see where it came from  *sad2*

So, it most certainly is an SRM job since I sent it to them and then drove a couple of hundred miles to collect it, and remember the payment wince. 

I had had it done since the 'big' ends are small and were already -40. Plus I had scoring on the main oil side journal (bearing had had it when I bought it) - Rather than find a new crank, I went for the conversion.

I appreciate the doubt about the thread strip issue - but as a time served toolmaker, I can assure everyone that it was not the removal - I had dressed the center punch marks away and really did not give it a big belt - it just tipped and moved down the hole a thread or so - There is silicon seal hanging to some of the threads which is odd - I would have expected Loctite?

But for the sake of the debate, what if the plug was sealed OK, where else to look?

This is all a curious issue - but in the end, it's just a matter of metal and money

It WILL run again   
Title: Re: Post big bang - Whitsend A10
Post by: metalflake11 on 15.05. 2014 20:32
Shame you didn't ring them before you stripped it, they might have done an autopsy depending on the circumstances.
Do you run an external filter?
Title: Re: Post big bang - Whitsend A10
Post by: morris on 15.05. 2014 21:03
Can I ask for the collective wisdom here - If the drive side plug was not sealing properly and allowing the oil pressure to drop, why did the bearing closest to the pump cop it?
Just an idea but I can imagine the timing side bearing giving up because of lack of pressure. Oil has, like any other liquid, to be forced to go where it otherwise wouldn't. So having a significant leak further up the line would mean a significant drop of pressure down the line.
OTOH, if this is the case I think the other bearing must have been close to collapsing also
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 15.05. 2014 21:16
Well yes, it is a shame - but more learning really   
It must be 13 years or so since I had it done and TBH it never entered my head to give them a call
I am not on a blame hunt, I just want to sort it so that I can run out without worry - the cause is not really clear and I would rather avoid it again   
As for a filter - no, I always changed the oil after 1500 miles max, so hey ho - this time.
I fitted a snazzy magnetic sump trap though three years ago  *smiley4*   
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 15.05. 2014 21:27
Hi Morris
I follow your thoughts and yes, I would suspect so
Just a whacky idea - I live on a Peninsula and set off from the north side clockwise, mainly left hand bends forcing the oil to the drive side!
I should have gone the other way - Damn     
Title: Re: Post big bang - Whitsend A10
Post by: morris on 15.05. 2014 21:41
Hi Morris
I follow your thoughts and yes, I would suspect so
Just a whacky idea - I live on a Peninsula and set off from the north side clockwise, mainly left hand bends forcing the oil to the drive side!
I should have gone the other way - Damn   
*smile*
Or mount the engine inclined sideways....
Title: Re: Post big bang - Whitsend A10
Post by: metalflake11 on 15.05. 2014 21:56
They don't have a 'not our fault' attitude, they want to know for their own benefit. After all these years they obviously wouldn't fix it for free, but they might have discounted some parts or the labour. They may still do so.
You've been very unlucky in my opinion.
Title: Re: Post big bang - Whitsend A10
Post by: WozzA on 16.05. 2014 00:06
Hi Morris
I follow your thoughts and yes, I would suspect so
Just a whacky idea - I live on a Peninsula and set off from the north side clockwise, mainly left hand bends forcing the oil to the drive side!
I should have gone the other way - Damn   
*smile*
Or mount the engine inclined sideways....

Ahhhh Haaaaa...  BUT if you ride home the same way ALL will equal out...   *roll* *sad* *whistle*
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 16.05. 2014 00:26
Hmmm, but if I kept going right on my Peninsula journey - I would have arrived home  *conf*

!! avoid all left hand journeys
Title: Re: Post big bang - Whitsend A10
Post by: KiwiGF on 16.05. 2014 02:52
A big end failure after so few miles is concerning.  Does the other big end show signs of wear?

Oil supply failure to the big ends sounds a likely root cause. Is the srm feed arrangement in good condition?

Is the top end work needed unrelated?

Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 16.05. 2014 08:01
Hi KiwiGF
I tend to agree - As far as I can see the oil system is in A1 condition, but I have not yet taken the oil pump apart - it feels fine though when I turn it. Hence my suspicion about the end plug leaking and loosing pressure
The drive side big end is showing slight signs  - it could just be the result of debris from t'other though - I will post some pictures later, but now need to go to work to earn the repair tokens
The top end work is needed since the broken con rod a) caused a cracked barrel skirt and b) rammed the piston into the head
As the valves tried to open against the piston crown, it dramatically bent the push rods, I have yet to see if the valves are distorted in any way - I am mentally preparing for the worst, but can't bear to look yet
But it WILL run again
   
Title: Re: Post big bang - Whitsend A10
Post by: Topdad on 16.05. 2014 13:08
Well said Charles keep on with the progress reports regards Bob.
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 16.05. 2014 21:55
I'm afraid to say the valves will be RS as well Charles.
Similar to my A65 blow up, rod little end missing. Could that have started the ball rolling. Mine was making a rattle for some time before it went bang, the big end bearings weren't too bad.
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 16.05. 2014 22:05
I filled the head with alcohol to see if it leaked tonight
Good news - only rubbish came out
 *smiley4*   
Title: Re: Post big bang - Whitsend A10
Post by: chaterlea25 on 16.05. 2014 22:16
Hi Charles,
The failure had to be due to a lack of oil pressure
You said that the bike was left idle for 5 years, ?
If left idle the oil pump bodies can grow and jam the gears !, equally the mazac can go porus and leak all the oil out *eek*
Have you checked the pressure relief valve?
I would have thought that if loose the crank plug would have been blown outwards by the oil pressure???

HTH
John
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 16.05. 2014 22:46
Hmmmm - some interesting points there, thanks 
Yes, a lack of oil pressure is the big issue
Just been to check the oil pump and all as fine - in fact when I ran it up there was a very healthy oil return to the tank (spent ages kicking it over with the plugs out til it did so)
now for the relief valve - I will have a look and let you know
Cheers
Charles     
Title: Re: Post big bang - Whitsend A10
Post by: WozzA on 16.05. 2014 22:47
I filled the head with alcohol to see if it leaked tonight
Good news - only rubbish came out
 *smiley4*   
I have the same problem ..   *beer*
Title: Re: Post big bang - Whitsend A10
Post by: orabanda on 17.05. 2014 00:43
I was told the bike would go faster if you shaved the head; well it didn't - but my ears were colder!
Title: Re: Post big bang - Whitsend A10
Post by: a10gf on 17.05. 2014 02:02
Quote
I am mentally preparing for the worst, but can't bear to look yet
But it WILL run again
*good3*
Title: Re: Post big bang - Whitsend A10
Post by: duTch on 17.05. 2014 09:14

 
Quote
I filled the head with alcohol to see if it leaked tonight
Good news - only rubbish came out
 *smiley4*   

 Yea got the jump on me there Wozza- I wozza thunkin' the same thang....!!! *beer*
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 18.05. 2014 11:36
Your broken bits (posted in another topic http://www.a7a10.net/forum/index.php?action=dlattach;topic=8385.0;attach=25186;image) look a lot like my A65's bits.
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 18.05. 2014 20:35
Any-one know what this is?   
Title: Re: Post big bang - Whitsend A10
Post by: RichardL on 18.05. 2014 20:44
The freeze plug from your Chevrolet?
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 18.05. 2014 21:01
Well, whatever it is, it shouldn't have been in my eckin oil tank!!!!!!!!!!!!
I think i have found the problem
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 18.05. 2014 21:06
Yep, we call'em welsh plugs down here. It shouldn't be inside your motor.
I'll take a guess, It was behind the sludge trap screw?
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 18.05. 2014 21:17
Well no - it was in the bottom of my oil tank!! - it must have been re-invigorated with the last oil change and covered the oil feed   
I have a small journal with no gubbins behind - ???????
But how the heck it got there God knows - I swear I flushed it all out on the rebuild
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 18.05. 2014 21:24
So your tank doesn't have the tall standing gauze filter. http://www.ebay.com.au/itm/BSA-A7-A10-B31-B33-GOLD-STAR-OIL-TANK-FILTER-/330735220351?pt=UK_Motorcycle_Parts_13&hash=item4d015af67f
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: ShaunMac on 18.05. 2014 21:25
Wow....I only had sludge and a few bits of metal in my tank!
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 18.05. 2014 21:27
Well, actually yes it does - But............Oh no, good call, I thought it was sussed
More sleepless nights!
Title: Re: Post big bang - Whitsend A10
Post by: chaterlea25 on 18.05. 2014 21:31
Hi Charles,
It looks like the sealing plug from an oil tin??

I'm really surprised that there are three threads going on at the same time and all three share the sludged up oil tank syndrome ???

Maybe I'm paranoid but I wash out the oiltank at every oilchange and have added a drain plug to the tank bottom to aid in this
Theres a photo of my tank drain setup in this thread
http://www.a7a10.net/forum/index.php?topic=1274.msg9205#msg9205

HTH
John
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 18.05. 2014 21:50
Excellent - I will fit one before it runs again
Thanks
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 09.06. 2014 19:56
Help with a judgement call guys please
Is only perfection acceptable for the surface of the big end journals?
In the mash up, I have had one shell, ermmm clattered, and one with a few marks - big issue, they are -40 already
If I run my fingernail over the journals there are some 2 to 4 thou 'ish'scores
Given I can sort the oil pressure issue, do I need the regrind? - Feels very final
Cheers
Charles     
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 09.06. 2014 20:33
Errrrrmm, anyone know why the drive side big end journal would have a bigger oil feed hole than the timing side?
Sorry all - Been on a course today and been told to address my positive mental attitude.
Well. definitely , I am positive it is broken
Cheers
Charles   
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 09.06. 2014 20:51
G'day Charles. In a perfect world it would need doing. If it's only light scoring, give the journals a good polish and measure them. 1.421"-1.420" is great, 1.419" is just OK. Any less and it's bodge time.
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 09.06. 2014 21:22
Hi Muskrat
Thanks, its a small journal and according to big mike reads 1.223 inch
Inspired I have been and given it a polish - It looks fine and the marks were much less than 2 thou
I owe you a Welsh beer now
Cheers
Charles 
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 09.06. 2014 21:53
Many thanks indeed Muskrat
Here it is all smooth and shiny
Cheers
Charles
Title: Re: Post big bang - Whitsend A10
Post by: trevinoz on 09.06. 2014 21:59
It looks like that crank has been dynamically balanced , Charles.

Trev.
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 09.06. 2014 22:14
Hi Trev
Well spotted - Yes it has, it had a full on SRM bottom end re-furb
Before, it shook all the blood out of my arms and made my eyes blur at about 60mph
Much better after, and when I spotted the bottom mounting bolt had still shaken itself out - perfect!
Cheers
Charles
   
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 09.06. 2014 23:31
" its a small journal and according to big mike reads 1.223 inch"
Std sml journal is 1.461" - 0.040 = 1.421. Is that a typo, micrometer miss-read???
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 09.06. 2014 23:58
Oh dear, thanks again
Can we agree to leave it as a typo?
Its 1.420
:-))

 
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 22.06. 2014 12:04
I'm afraid to say the valves will be RS as well Charles.
Similar to my A65 blow up, rod little end missing. Could that have started the ball rolling. Mine was making a rattle for some time before it went bang, the big end bearings weren't too bad.
Cheers
Thanks Muskrat
Yep - I put some spirit in the cylinder head (for a change) and the valves are badly damaged
I have decided on a second full rebuild - I have roped the missus, in bless her. Dog still looks worried   
Title: Re: Post big bang - Whitsend A10
Post by: orabanda on 22.06. 2014 12:29
Hi Charles,
RD250, or RD400 in the background?

Your choice of twins, 2 or 4 stroke, is excellent!

Richard
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 22.06. 2014 12:41
Hi Richard
It's my old RD250 - I have had it about 24 years
but sadly its going to have to go now to fund the BSA - it's been a dilemma really since it's not very comfortable for us to go out on - a bit on-off resulting in banging helmet syndrome!
But unusual since it has a mag alloy drum brake wheel on the back
Hey ho
Charles 
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 22.06. 2014 12:53
Sit-rep
Valves bent, guides damaged = full head refurb
Crank looks OK after a good polishing
Cylinder barrels need major re-engineering - Gulp
Mag going off for refurb just to be safe - works but slightly wobbly
Now the rest of it is coming to bits - Gearbox next
and then new spokes, tarted up paintwork, some more S/S nuts and bolts, bags of polish
and then a run out
and thanks in advance for your help that will doubtless be needed
Cheers
Charles
   
     
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 22.06. 2014 13:15
Your spoiling the missus mate. Carpet, padded seat, glass of drink. Better not let mine see that picture.
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 22.06. 2014 13:29
 ;)
Title: Re: Post big bang - Whitsend A10
Post by: bsa-bill on 22.06. 2014 14:04
 I recall  one of you colonials  telling me  that If your missus could get into your shed her chain was too long.
This was long before this forum and it's cultural ethics existed *whistle*


Helmet on -------- duck *countdown*
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 27.06. 2014 13:32
Been doing some more inspection work and although I have trawled the previous posts, I need reassurance please
Valve stems measure 2 x 0.310 and 2 x 0.311
In the guides, with the valves close to shut, I can detect about 5 thou deflection at the tappet end of the shaft (worst case)
It sounds OK to me, but then again, I am a bit sensitive just now
Would that seem OK to the collective wisdom?
Cheers
Charles 
Title: Re: Post big bang - Whitsend A10
Post by: cyclobutch on 27.06. 2014 16:58
I have a pal looking out for an RD250/400 at the moment ...
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 27.06. 2014 18:14
Hi Cyclobutch
Thanks for the message - I am resigned to this year being lost to repairs.
After I dragged the RD out and polished it for sale, we had a reminisce, and rather than have no bike at all, we have brought it out of retirement
Once the A10 is up and running again, we will certainly sell it though
And it's moving on already, some more parts sorted through kind forum members - lovely place to be!
Thanks everyone
Cheers - Charles

 
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 27.06. 2014 21:06
Those figures sound OK to me Charles. Is that new valves in old guides or new?
Cheers
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 27.06. 2014 21:53
To be honest, I really don't know. It pre-dates me
But I have a feeling the head had been redone before I bought it - the rocker bushes and all seems still sound. big chunk of fin missing though
These are the inlet and exhaust vales from the undamaged side
I am a little concerned about the blue seat area, but a good grinding in will sort it - no pitting
Cheers
Charles
   
Title: Re: Post big bang - Whitsend A10
Post by: BSA_54A10 on 28.06. 2014 07:26
Inlet runs red hot so it will be blue if not black.
With modern fuels I tend to use a much thicker contact face than the old days around 3/16"
And the 3 angle cut seems to have worked a lot better than the usual 2 angle job
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 28.06. 2014 14:41
3 angle? presumably that needs a machine shop
I was thinking of just regrinding them in myself in the traditional way, but more than happy to try it
Cheers
Charles
Title: Re: Post big bang - Whitsend A10
Post by: Triton Thrasher on 28.06. 2014 15:59
Inlet runs red hot so it will be blue if not black.

I think the exhaust valve is the hot one.
Title: Re: Post big bang - Whitsend A10
Post by: BSA_54A10 on 29.06. 2014 14:37
Inlet runs red hot so it will be blue if not black.

I think the exhaust valve is the hot one.

OOps, then again it was a really good shiraz
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 29.06. 2014 17:19
Should I put more spirit in the inlet valve!
Title: Re: Post big bang - Whitsend A10
Post by: charles whitfield on 30.06. 2014 19:15
Thanks everyone - found the root of the problem I think
I stripped the piston from the undamaged conrod - the top conrod oil feed hole is not in line with the hole in the bush - it looks like it has turned, but not sure why?
Would it be fair to assume the same had happened on the broken side, causing the bush to fail? etc, etc
When I bought the new NOS conrods, the seller immediately said it sounded like it had not been line reamed and that was the cause
Opinions welcomed
Cheers
Charles
Title: Re: Post big bang - Whitsend A10
Post by: muskrat on 30.06. 2014 20:35
That could be one reason. A good inspection of the bore and pistons should tell. Is there marking other than fore and aft? Another cause could be pinging hammering the L/E bush loose. Or the PO has replaced the L/E bush's and done a bad job of it. A lot of books say to push the old bush out with the new one going in. Don't *ex*. Heat the rod, press old bush out, freeze the new bush and it should drop in or only need a little shove. ALWAYS check for square and true before use.
Cheers