The BSA A7-A10 Forum

Technical => A7 & A10 Engine => Topic started by: AdrianJ on 04.10. 2019 17:32

Title: Rock solid engine.
Post by: AdrianJ on 04.10. 2019 17:32
Help please with ideas and how best to proceed.
Started the plunger A10 engine with the intention of going for the first test ride.
Carb seemed to be sticking when I opened the throttle so I killed the engine. Stopped as soon as I hit the button, no overrun at all.
Now the engine seems to be solid.
Clutch is working.
I have taken off the rocker box covers and I think the push rods are in place.
Can't turn the crankshaft with a spanner.
Kick start is solid but turns when clutch is disengaged.
Have now removed the gear box cover and the kickstart mechanism is fine - didn't really think it was this.
Yes - I do have an oil return!
Unfortunately can't get back to work on it till Wednesday.
I'm mystified. Next step rocker box off, try to turn the engine?
Any ideas what to do next head and barrels off?
Regards,
Adrian.
Title: Re: Rock solid engine.
Post by: Swarfcut on 04.10. 2019 18:50
Hi Adrian. Whoops, or a similar expletive. Sure its not left in gear in the confusion? OK, clutch disengaged, kickstart moves, mainshaft and layshaft are free.

 As a start, whip off the sump plate. A good cup of oil should be in there. Full to the brim? Hydraulic lock.  Dry as a bone? The engine has probably seized.
 Get the primary cover off, and remove the clutch springs. This effectively separates the engine and gearbox and if you find the crank now moves OK, then the fault is in the clutch.

  Crank still solid? Carb could have put neat fuel into the bore, washing off the oil, so see  if the pistons are seized in the bores by lifting the barrel which may allow the crank to move and turn slightly. Pistons moving OK in the bore as the barrel lifts but crank still locked solid? Good chance the timing bush has seized on the crank, a big end seizure or the camshaft is locked up. Something as simple as a jammed cam follower could do this, so if pistons and crank move normally with the barrel lifted an inch or so this is where to look. Seized rockers possible, easy to check but unlikely. No need to take off the head yet for these simple checks. Jammed or seized timing gears are again possible but unlikely.

Be methodical, but as it stopped without any major clank or bang it will require a bit of detective work to find the fault.

Swarfy.
Title: Re: Rock solid engine.
Post by: AdrianJ on 04.10. 2019 19:15
Great - thanks very much Swarfy.
I'll get down to it o Wednesday when I'm back.
Regards,
Adrian
Title: Re: Rock solid engine.
Post by: chaterlea25 on 04.10. 2019 19:53
Hi Adrian
Buggershitnfuck *ex*
Oil returning is no guarantee of oil getting to the main and big ends??
Is the engine just after being rebuilt?
If so did you prime the crankshaft oil gallery?

John
Title: Re: Rock solid engine.
Post by: AdrianJ on 04.10. 2019 19:55
I did but it sat a long time vefore I finally started it. *sad2* *sad2*
Adrian
Title: Re: Rock solid engine.
Post by: muskrat on 04.10. 2019 21:15
G'day Adrian.
Double bugga. You have tried turning over with the plugs out? Are the pistons up or down the bore?
Follow Swarfy's suggestions but have a good look in the timing chest first.
Cheers
Title: Re: Rock solid engine.
Post by: AdrianJ on 04.10. 2019 22:00
Yep Muskrat. Plugs out no change.
Wednesday I start to take it apart
 *sad2* *sad2* *sad2*
Title: Re: Rock solid engine.
Post by: Black Sheep on 05.10. 2019 06:44
This once happened to me. Stopped for petrol and went to start and engine was solid. Was towed 100 miles home. Once the timing cover was off it was obvious what had happened. A bit had fallen off the ATD and fallen between the timing gears.
It may not be anything drastic after all...
Title: Re: Rock solid engine.
Post by: Swarfcut on 05.10. 2019 09:48
Adrian, just had another thought. A good dose of WD down the bores will do no harm while it stands for a few of days, may help free off a tight piston.  Sorry to have painted the blackest picture, other folks have a more optimistic outlook on life! I reckon it will be a simple explaination.

Swarfy.
Title: Re: Rock solid engine.
Post by: BSA_54A10 on 05.10. 2019 10:40
Lots of silly things can lock the engine solid
the dynamo can sieze
The magneto can sieze

So as suggested, off with the timing cover and pull the idler pinion to take the magneto out of the equation
While you are there watch the dynamo chain , if it is still there and see if it is straining as you try to turn the engine over.
Also pull the sump off and slip your pinkey inside the crank case feeling for metallic trash.
Title: Re: Rock solid engine.
Post by: muskrat on 05.10. 2019 11:46
To add to Trevor's post. Only take the idler pinion out if the pistons are at tdc. If it isn't and the cam has a valve down and you take the idler out and turn the crank (if it turns) there's a good chance of bending a valve or two  *pull hair out*
Cheers
Title: Re: Rock solid engine.
Post by: Greybeard on 05.10. 2019 17:10
You mention a stuck open throttle. If the engine was revved hard before oil got to the bores a piston may have picked up in the bore. Has either (or both) exhaust header blued? An indication of excessive heat.

I know some people here do not believe in lubricating a new piston/rings/bore, as they feel it slows down the break-in period but I've always oiled my pistons on every engine build I've done. If my engine had been standing for a while since a rebuild I would have squirted oil down the plughole.
Title: Re: Rock solid engine.
Post by: ironhead on 05.10. 2019 22:55
You mention a stuck open throttle. If the engine was revved hard before oil got to the bores a piston may have picked up in the bore. Has either (or both) exhaust header blued? An indication of excessive heat.

I know some people here do not believe in lubricating a new piston/rings/bore, as they feel it slows down the break-in period but I've always oiled my pistons on every engine build I've done. If my engine had been standing for a while since a rebuild I would have squirted oil down the plughole.


With oil, too much is waay better than not enough.
Title: Re: Rock solid engine.
Post by: Rex on 06.10. 2019 09:52
With just a smear of oil on the rings and no more added. Always worked well for me.
I remember reading about an old bike racer and tuner back in the Brooklands days who would leave the freshly-bored barrel out on the lawn overnight to get a thin film of rust, then assemble it dry and rev it to the "bloodline" (as he termed it) a couple of times and the bike was ready to race. No gentle running in required. ;)
Title: Re: Rock solid engine.
Post by: Greybeard on 06.10. 2019 10:23
With just a smear of oil on the rings and no more added. Always worked well for me.
I remember reading about an old bike racer and tuner back in the Brooklands days who would leave the freshly-bored barrel out on the lawn overnight to get a thin film of rust, then assemble it dry and rev it to the "bloodline" (as he termed it) a couple of times and the bike was ready to race. No gentle running in required. ;)
Horses for courses. A race bike might have a new engine every race. A private bike needs to go for many years between rebuilds.
Title: Re: Rock solid engine.
Post by: BSA_54A10 on 06.10. 2019 12:15
We will have to agree to dissagree.
Dry bores and a 3 minute run in.
Different with a fully rebuilt engine where you have replaced bushes & bearings but for a simple rering dry .
Even when I do a full rebuild, the rigs get gurn in dry then I baby the rest of the engine for it's first couple of hundred miles, changing the oil every 50 or so followed by a retorque on the head.
Title: Re: Rock solid engine.
Post by: Rex on 06.10. 2019 15:58
Horses for courses. A race bike might have a new engine every race. A private bike needs to go for many years between rebuilds.

True of course, but the principle here is that the rings are bedded-in ASAP. BTW I wouldn't attempt the "bloodline" bit either!
Modern oil is so good that it seems to be a common problem on the Net of people who've smothered the pistons  and bores in high quality oil only to find that the engine is still smoking like a WW1-era frigate many miles later, which, as we all appreciate, means doing the job all over again..
Title: Re: Rock solid engine.
Post by: RDfella on 06.10. 2019 17:52
And how does all this work when you've got chrome bores? Been building engines (almost all rebored) since 1960 and for a living mid 70's on, and always put plenty of oil on the piston and rings and never had a problem. I've heard you shouldn't use a top quality oil for running in, but I always used either straight 30 for diesels or 20/50 for petrol. Mineral, naturally.
Title: Re: Rock solid engine.
Post by: AdrianJ on 09.10. 2019 17:38
Latest update.
I have removed rocker box, timing covers and primary chaincase.
Rockers are free.
Removed idler (half time)  gear in timing chest.
Camshaft and magneto are free. Dynamo is free. Crankshaft still locked.
Small amount of black sludge (teaspoon) in the sump.
Haven't taken the clutch off but the outer sprocket has some hooked teeth, which I did not notice on rebuild.
On Friday I will remove the clutch, head and barrels.
I should know what's what after that.
Regards,
 Adrian.
Title: Re: Rock solid engine.
Post by: a10gf on 09.10. 2019 19:18
Sorry for the need\cause for this detective work, but looking forward to reading news of your findings (and hopefully a good solution), good luck.
Title: Re: Rock solid engine.
Post by: Swarfcut on 11.10. 2019 08:44
Adrian...I have just read through your earlier posts to get a handle on your problem. If you have done all you intended, the motor has a new SRM pump, new pistons, rebore,  new timing bush and a crank grind.....can't tell if you had the journals metal sprayed and ground back to standard.  Nor can I tell with a quick read whether this was the first time it has run since the rebuild.

 You are familiar with the engine from your experiences with a later S/A model, if I understand correctly, so please confirm whether these basic assumptions are correct.

 Your last post indicated the sump was "dry" as if the small amount of sludge  in there was all to be found.....no trace of any oil. So we await the next instalment.

Swarfy.
Title: Re: Rock solid engine.
Post by: AdrianJ on 11.10. 2019 09:11
Hi Swarfy,
Thanks for looking at that lot.
Most of your assumptions are correct. Yes I have done all you mention. No metal spraying just a regrind to first undersize.
Third time run, previous were just a couple of quip blips, total running time less thsn three minutes.
No there was oil in the sump it just hadn't wet sumped. The sludge was in the oil and on the magnetic drain plug, which is not near the non return valve.
The SRM pump turns freely by hand and was full of oil, oil also seems to be getting to the rockers, there was oil in the banjo unions.
Today the clutch and primary drive come off. Clutch is quite wobbly.
Regards,
Adrian.
Title: Re: Rock solid engine.
Post by: Swarfcut on 11.10. 2019 10:50
Adrian, Just a mention about the clutch...as long as the small "half  circle retainers" are in place and supporting the thrust washer behind the clutch drum, the clutch inner will be hard against the thrust washer as the centre nut is tightened. The only lateral support  for the chainwheel is in effect the running clearance between the thrust washer face, the back face of the inner drum and the faces of the chainwheel. Too tight.....it drags and seizes. Too loose...it wobbles. The centre rollers are too narrow to prevent all the wobble. To quote a saying "They all do that, Sir" In practice as long as the chain doesn't catch the inner chaincase, that's good enough for now.

 If you had oil return, oil was being pumped into the engine. If the PRV was blowing off too early, low pressure to the crank would mean possible seizure here.  As it has been rebored, a better chance it is a bore seizure, as long as the pump and PRV are working OK.

 I could be wrong, but that is where I'll put my money.

Swarfy.
Title: Re: Rock solid engine.
Post by: AdrianJ on 11.10. 2019 11:05
Swarfy,
Sounds like I didn't tighten the clutch enough.
The retainers are there - the chain had caught on the inner chaincase when I got the bike so it's difficult to tell if it's happening now.
If it was a bore seizure - why would it now be free? I had it relined back to std as it was at +60.
 I'm not sure it's any stiffer than when I'd finished putting it together.
I think I'll take the head off and have a look - it'll make retiming it easier anyway. I wonder if the liners could have slipped - not lipped! I'll find out tomorrow.
Regards,
Adrian
Title: Re: Rock solid engine.
Post by: Swarfcut on 11.10. 2019 11:22
Adrian....I thought it was still locked up, didn't realise your bore and pistons are free.
Title: Re: Rock solid engine.
Post by: AdrianJ on 11.10. 2019 11:36
Swarfy,
Sorry - I've just realised one of my posts seems to have gone missing.It said that everything was locked up till I took the clutch and engine sprocket off. I've put the engine sprocket back on temporarily and it's still free but stiff.
It surprised me - thought it would be crankshaft or pistons.
Still a bit stiff but I'm not sure it's too stiff.
After I've had the head off I'll try rebuilding but it may be some time as I think I do need a new clutch basket. I the teeth aren't badly hooked but they are very sharp and shiny on the reverse - wonder if they have hit the chaincase. I could dress them and rebuild with this clutch.
Regards,
Adrian
Title: Re: Rock solid engine.
Post by: Swarfcut on 11.10. 2019 12:25
   I would be inclined to lubricate the bores, take off the PRV and rotate the engine gently on the crank drive sleeve and check for an oil feed into the PRV cavity. Assure yourself the PRV is serviceable, and fingers crossed you have oil to the crank.  Try it again without lifting the head......any damage is done, and as long as it is free, see if it will go. Bear in mind a well built engine will be fairly stiff, not like it was when you first got the bike.  For a short term test stick with the old clutch unless it is so worn that the chain is riding up on the teeth and jamming on the case....fresh evidence of contact will be apparent.  Common for a piston that has just nipped up to free off, sometimes you can be lucky. Still thinking if it was the clutch, there should be something clearly amiss and fixable.

Swarfy.
Title: Re: Rock solid engine.
Post by: RichardL on 11.10. 2019 12:46
Well, I just tried to read most of this thread for the first time. On the simplistic side, has it been confirmed that the sludge trap was cleaned prior to restarting after sitting for some time (years, perhaps)? Wiped out rod bearings could have a tiny impact on smooth or frozen crank rotation.  *eek* ;)

Richard L.
Title: Re: Rock solid engine.
Post by: Klaus on 11.10. 2019 13:12
Hi Adrian,

you've wrote there was only a teespon black sludge in the sump. So there was no oilfeed to the crank, it sounds to me.

Years ago I bought a new SRM Oilpump, but it was not plug and play. I fit this pump normal way and the crank were solid. When I loosen the bolds the crank were free to rotate. Tighten the bolds, crank jammed. I've heared from a blocke there was a burst engine because the wormdrive was brocken to rotate the gears from the oilpump.
So please have a look at your Oilpump if she realy feed.

Cheers Klaus
Title: Re: Rock solid engine.
Post by: AdrianJ on 11.10. 2019 14:16
RichardL- yes the sludge traps were cleaned.
Klaus - I meant there was a teaspoon of black sludge along with the oil, not making myself clear. The oil pump must be feeding because I get an oil return.
Swarfy - yes I'll lubricate the bores, check the PRV - although I think it was working after the rebuild, at least oil was getting to it because that was how I checked that the pump was primed,  and try the clutch again tomorrow.
Regards,
 Adrian
Title: Re: Rock solid engine.
Post by: orabanda on 12.10. 2019 00:11
Despite the fact that the engine was running, check that the three 5/16" primary cover screws are not touching the crankshaft when tightened (too long).

Also, that primary drive sprocket nut is not fouling primary drive cover.
Richard
Title: Re: Rock solid engine.
Post by: duTch on 12.10. 2019 00:46

 
Quote
.........check that the three 5/16" primary cover screws are not touching the crankshaft when tightened 9too long).......

 Also the two internal rear ones (particularly the bottom one I think) that hold the inner case to the crankcase-
Title: Re: Rock solid engine.
Post by: Swarfcut on 12.10. 2019 10:51
Good thoughts there, Gents, but this engine is the earlier Plunger Type, with the inner chaincase being part of the primary side crankcase casting. Long bolts only apply to the later S/A engine....the plunger does not have them.

Just wonder if sludge trap plugs ever come loose to foul the cases...evidenced by metallic shavings in the sump and a rhythmical crank speed clunk?

Swarfy.

Additional....plus bearing failure because of lack of oil pressure.
Title: Re: Rock solid engine.
Post by: Rex on 12.10. 2019 11:08
Sounds like a possibility. Not a lot of clearance if one does start to unwind.
Title: Re: Rock solid engine.
Post by: duTch on 12.10. 2019 15:15

 
Quote
......Gents, but this engine is the earlier Plunger Type, with the inner chaincase being part of the primary side crankcase casting. Long bolts only apply to the later S/A engine....the plunger does not have them.....

 True enough- I didn't read back to reference which model but the plungers chain tensioner studs are in the same or close to the S/A rear ones, so if they've been changed to longer..... as I had to, having lost the original ones.

Title: Re: Rock solid engine.
Post by: AdrianJ on 12.10. 2019 15:21
Starting to get somewhere at last.
The engine is now free and I can turn it with one hand with a spanner on the crankshaft.
The clutch chainwheel has been cutting into the inner timing case. (Photo attached).
It was like this when I got the bike but worse now and the are some markings on the chainwheel teeth. (photo attached)
The chain still seems OK.
I strongly suspect that the engine never seized but the clutch locked against the timing case. As soon as I got the transmission off the engine was free
I tried experimentally replacing the clutch. Tightened it sensibly and there was still wobble. I tried a bit more of a heave on the clutch nut and it suddenly freed, got another 1/2 turn off it and the wobble on the clutch has gone. It looks to me like this is the problem.
A minor irritation - as I loosened the cylinder barrel nuts two of the studs started to unwind. So I'll have to put that right.
Does the chainwheel still look OK or do I have to take out a mortgage to get one from Holland?
Regards,
Adrian.
Title: Re: Rock solid engine.
Post by: ellis on 12.10. 2019 20:35
Hi AdrianJ,

I have seen some much worse than yours and were still operating just fine, so i wouldn't be too concerned. I presume the needle rollers are of the correct size?
Hope this is some help to you and gets you back on the road soon.

ELLIS
Title: Re: Rock solid engine.
Post by: AdrianJ on 12.10. 2019 21:26
Hi Ellis,
I think they are OK. I'm hoping that if the clutch centre is tight enough it will be fine.It seems to need a lot of force to tighten it properly.
What worries me is that though the marks are worse now, some were there when I started.
I have replaced the original rollers. We will see :-)
Adrian
Title: Re: Rock solid engine.
Post by: duTch on 12.10. 2019 21:39

 Check that the new rollers are 1/4" x 1/4" and not 1/4" x 6mm as was used in unit construction clutches
Title: Re: Rock solid engine.
Post by: Swarfcut on 12.10. 2019 22:00
Adrian..Those teeth look reasonable as a try.  For new parts, C&D Autos had NOS Clutch Chainwheels, (a while ago) but there are still reasonable  numbers  of used chainwheels available on eBay.

Try tightening the big nut against the clutch centre, which should slide easily down the mainshaft splines to abut the thrust washer.

   The nut and tab washer will tighten  to clamp the clutch centre hard against the  thrust washer. A new nut and a clean up of the gearbox mainshaft thread may be required, lots of nuts get butchered, the tab washer is essential.  Correctly assembled the nut does its clamping before bottoming on the mainshaft thread. Various thickness thrust washers were originally available to align the chain and space the clutch sprocket from the chaincase. You could also loosen the gearbox/engine bolts (plus engine mountings) and try to move the box further to the drive side, moving the clutch position further away from the inner chaincase. Any circular shims to finely align the chain go between the splined crank drive sleeve and the main bearing inner race.
 In an ideal world you replace with new both sprockets and chain, or be like me and select the best of the rest for a reasonable low annual mileage runner.

To confirm duTch, the rollers are 1/4" x 1/4"

Swarfy.
Title: Re: Rock solid engine.
Post by: BSA_54A10 on 13.10. 2019 05:06
If the clutch center will not tighten down easily check for burrs on the edges of the key ways both on the mainshaft and inside the clutch center.
Then get some Brasso and use it to lap the shaft taper to the clutch center.
It is common for one that has not been snugged up properly to wear a little ridge which prevents the hub locking onto the shaft.
Title: Re: Rock solid engine.
Post by: muskrat on 13.10. 2019 09:13
Plunger type Trev.
G'day Adrian.
Check the cotters (abutment rings) will fit into the thrust washer all the way without binding. Check for burrs on the shaft and center.
Cheers
Title: Re: Rock solid engine.
Post by: AdrianJ on 13.10. 2019 09:52
Thanks Dutch, Swarfy, Trevor and Musky,
Will check threads, rollers and burrs tomorrow and put it back together.
I have a new nut.
I've been unimpressed by the quality of a lot of new parts, including a crankshaft nut with no thread :-)
Adrian.
Title: Re: Rock solid engine.
Post by: Greybeard on 13.10. 2019 09:53
If the clutch center will not tighten down easily check for burrs on the edges of the key ways both on the mainshaft and inside the clutch center.
Then get some Brasso and use it to lap the shaft taper to the clutch center.
It is common for one that has not been snugged up properly to wear a little ridge which prevents the hub locking onto the shaft.
No taper on these clutches Trevor and no key ways. The shaft is splined.
Title: Re: Rock solid engine.
Post by: BSA_54A10 on 15.10. 2019 09:50
Sorry did not realize it was a plunger box.
Title: Re: Rock solid engine.
Post by: AdrianJ on 16.10. 2019 15:05
Thanks very much for your help everybody.
I have got the clutch back on and the engine turns over normally on the kickstart.
I still have a bit of play in the clutch - the centre is solid but the basket and chainwheel have a bit of rock - not enough tp reach the chaincase I hope. I have measured the size of my rollers and i get 0.246" but I'm not sure if my calipers are that accurate!
I'll just have to try it and see.
It'll take me a while to get the rest of the bike back together as I'm going away for a few days.
Thanks again for all the help.
Adrian
Title: Re: Rock solid engine.
Post by: Swarfcut on 16.10. 2019 17:23
Adrian, your rollers need to 0.25"   6mm is 0.2362", so yours look to be halfway between. Any wear on the clutch centre and basket tracks will make the situation even worse with undersize rollers, but  as long as you are sure it won't catch, give it a go while you look for some better parts.

Well done for being a lucky fella.

Swarfy.
Title: Re: Rock solid engine.
Post by: AdrianJ on 16.10. 2019 17:31
Thanks Swarfy.
 These are brand new rollers - I'm not sure it's not my calipers.
I'm hoping it doesn't catch - but if t does I'll know what it is this time.
I'm keeping an eye out for new basket and centre - there doesn't seem any point getting second hand as they may be no better.
Regards and best wishes,
 Adrian.
Title: Re: Rock solid engine.
Post by: Greybeard on 16.10. 2019 17:33
I'm really happy that your 'locked' engine was nothing too serious.  *smile*