The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => A7 & A10 Engine => Topic started by: mfhutchins on 22.06. 2012 02:34
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hi all,
i cant remember if i've introduced myself here yet but i bought a 63 super rocket a few years ago and just finished the rebuild of the engine. my main reason for doing it was to inspect the dreaded sludge trap. finally after a rebore (cylinders were off by a few thousandths), hone, new pistons, rings etc from don hutchinson in massachusetts i started her up last week and noticed smoke from the left muffler. after going online and reading about possible causes, tonight i pulled the muffler off and started it again hoping there was oil in the baffles of the muffler but it still began to smoke. the smoke starts after 1-2 minutes and gradually gets thicker and thicker until i reluctantly shut the engine off. the smoke is white. this bike is completely original and it looks as if there have only ever been a few thousand miles put on the engine. conrods looked great, valves looked brand new. this was my first ever rebuild of any engine and i took my time so i am justifiably frustrated about the smoke. it smells like burning oil now that i have the muffler off. my valve clearances are .010 and .012 and there is no audible clanking in the rocker box. i dont want to have to pull off the rocker box but my fear is that there is excess play in the valve guides (which i never inspected other than visually). i wish this were a wetsump issue but i fear it isnt because the problem is confined to the left side. the oil is returning to the oiltank in a healthy stream and there are no obstructions in the oil breather. have i eliminated all the easy stuff and do i need to take the top end off THAT I JUST PUT ON to check the valves?
i have a blog with some pictures of start to finish but i still have many more to put on with lots more commentary but ive been busy with the life, the wife and kids. here it is:
http://birminghamsmallarms.wordpress.com/
any guidance and wisdom would be greatly appreciated as all my vintage bike friends are dying to see the highly anticipated debut of my treasured bike. thanks,
mike
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Logically, any oil burning must be coming past the rings or down the valves. If you've just had your barrels bored, provided they've done a good job, it sounds like the valves are worth a look. However, A10's often smoke a little bit on the left due to the oil squirting out of the left hand con rod eye which is drilled to ensure oil flow through the crank. It is also possible that the valve guides are loose when the engine gets hot. It might also be worth doing a compression test to ensure you have decent compression on both cylinders, much lower compression on the left may indicate that the boring wasn't done as well as it should be. If the smoke is tolerable it may be worth giving it a chance to bed in.
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White smoke is NOT from oil burning !!!
Regards , Flatboy.
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White smoke? hmmmm... not oil?..... That went across my mind but mfhutchins says the smoke gets progressively worse and smells oily. As the problem is on one side only and is obviously quite severe I don't see what else it can be. Also, there is oil in the silencers. I dare say some oils smoke paler than others! ....mfhutchins, is the smoke really white or is there a hint of picasso? I also note that the barrels were honed, not bored. People are often reluctant to get barrels bored when really that's what they need. Original piston clearance would have been about 0.004". Once you get towards 0.010" as the barrels wear you will find you get piston slap and the rings 'barreling'. It is definitely worth checking the valves but normal wear and tear in that department does not usually produce as much smoke as you describe.
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to clarify, the cylinders were re bored, then honed. the cylinders were different sizes is what i meant to say. they were off by 3 or 4 thousandths.
the work at hutchinson is top notch although he does send this kind of work out.
the compression test seems like the easiest thing to start with. if that turns out normal i guess ill turn my attention to the valve guides.
the smoke seems whitish-grey. it gets progressively worse. i am nervous to ride the bike any distance from the house but i have heard a number of people on these forums (here and britbike) mention riding it 30 miles or so to "break in" the engine. i have a hunch that wont solve this problem but ive been wrong before. the fact that the right side exhaust is fine leads me to believe this is a valve issue. i never considered the compression test but will do one today.
a thought: if the piston ring gaps were all lined up would that result in these symptoms by allowing a free flow of oil past the pistons?
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i just talked with one of the guys at hutchinson cycle. i guess john healy has them drain the oil, pour lacquer thinner in the problem cylinder a few times to remove the oil on the cylinder wall. then use straight 30 weight non-detergent oil in the engine because it is closer to what the oils of the day were back in the 60s. modern oils arent good for breaking in a new engine, he says. then do a series of revving the engine and idling it to let the rings bed into the cylinder walls.
ill try this in addition to a compression test and we'll see how that goes.
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the smoke seems whitish-grey
My rules of thumb:
blue smoke > oil
black smoke > petrol
white smoke > water\condensation.
but whitish-grey, maybe some lacquer thinner residues?
btw, very nice looking bike you've got.
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Go back to rule one. Drain your crankcase before starting up, then see what happens.
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(where is the degrees button on a keyboard??)
Above the 5 on mine (shift - 5) Dutch, but of course varies with country and/or make.
Fairly light coloured smoke (whiteish light grey) comes from one side or the other from mine on start up after a decent lay off, usually but not always the drive side
Like many others have remarked it disappears after a short while.
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I have 40 miles on my A10 after a rebuild and left hand side smoking happens every cold start whether I drain the sump or not. The color is a bluish white and smells of oil. It disappears after a minute or two. Am presently running Spectro 20w-50 on advice of rebuilder. (No oil filter yet but it's on the list). My lawn tractor does it also and I have been to enough warbird shows to look forward to that blast of oil smoke when they fire up. Magical. But if it gets worse after a few minutes but not blasting oil out of the breather then I would think it is not wet sumping that is happening. Sorry I can't offer more than that!
Rick D
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G'day Mike,
you may have also broken a ring putting the barrels on. What type of oil rings, one piece or three? I have had one (3 piece type) pop out of its groove and destroyed a new bore. Symptoms very similar to yours.
A loose valve guide will also give these symptoms but you will usually hear the racket in the rockerbox.
Cheers
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Hi Mike,
A few more thoughts!!
What make pistons/rings have been fitted to your engine?
The "no name" or modern "Wassel" branded Hepolites suffered from very poor ring quality
I am now informed that "Hastings " rings are fitted, BUT have not tried these??
Maybe a ring has broken or fitted upside down??
To check whether the oil is coming down from the head , block the feed to the rockers and run the engine
Theres only a very small quantity of oil delivered from the return to the oiltank
Have you replaced the rocker oilfeed bolts? these must have the correct size metering hole
Hope this helps
John O R
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i used the hose clamp method of compressing the rings. so, muskrat, this could be possible.
let me explain what i found today. on one attempt of kickstarting the bike i realized the plugs werent screwed in all the way so i screwed them in. now i noticed in the flat area where the spark plug bore sits, there is a small puddle of oil/fuel (ok) with very fine metal shards. (not ok) i figured this may be from the new rings and fuel when i was kicking it over but now im thinking it may be pieces of broken ring.
also, when i poured the lacquer thinner in a few times (small omounts each time) and rotated the crankshaft once, i got this milky white substance pouring out of the sump plate opening.
is there any way to test for a broken ring without taking the barrel off?
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chaterlea25, the pistons were italian. gandini, i think.
many things on my bike are original and the oil feed bolts look to be 2 of them. i am hesitant to replace them since they seem to be working fine.
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the pistons came with the rings already fitted. although i inspected them, i am pretty certain none were upside down.
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I think its time to inspect the top end again! Lifting the head and barrels isn't such a big job and its the only way you're going to find out what the problem is. Even if you find out what the problem is without lifting the top end off you're still going to have to dismantle it to fix the problem.
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i am so discouraged. all in all, i have hundreds of hours on this bike and now i have to take the engine 1/2 apart just to see if i have a broken piston ring.
i know, i know. welcome to british bikes.
and my gaskets were doing such a great job...
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Unfortunately these things happen Mike.
Gandini, or commonly known as GPM (different names same factory) pistons are a good piston. There does seem to be some variation with the rings on them and something you may need to check. In my experience with them the top ring and the oil ring can go in either way up but some of them come with a stepped scraper ring and this must be correctly fitted. They should have come with fitting instructions in the box but if not the step or rebate faces down.
You need to inspect the rings very carefully and see if there are any markings on them to indicate which way up they go, they should have a very small T by the gap. Also make sure the end gap is correct, around .010".
If you are unsure about any of this I would seek advice from an engineering firm or someone reputable near you.
Look upon it as a learning curve, when you have got the bike running well and you are enjoying a ride on a nice day all this will be forgotten. *smile*
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I cannot find the article / thesis I read about pre- ignition & detonation
but clouds of white smoke pour out the bike before it comes to a dead stop.
Detonation kills a motor real quick , holed piston ; furthest from the plug/ opposite the plug.
Cheers , Flatboy.
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The clouds of white smoke caused by pre-ignition is the discharge of melting aluminium (piston). I don't think mfhutchins's Super Rocket has got that hot yet!
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Perhaps a nicotine patch on the left cylinder will fix it!
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att. wilko, lol, I am often posting general reminders to not stray offtopic in the tech boards, but this one was a very good offtopic and ontopic. Congrats.
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i am so discouraged. all in all, i have hundreds of hours on this bike and now i have to take the engine 1/2 apart just to see if i have a broken piston ring.
i know, i know. welcome to british bikes.
and my gaskets were doing such a great job...
Hi there,
Don't be discouraged at all. This has happened to all of us at some time or other, Just bite the bullet and go to it!
This time though, "go through it with a fine tooth comb" check everything you possibly can. Strip the head completely and if in doubt about anything, Change it or sort it, don't pass it off or you may be going through this again next week. While the head is off, just whip the barrels off too and double check! At this stage it's not so much work.
The big thing to learn here is the one golden rule we use in our shop. Leave no stone unturned! And turn it slowly and check it thoroughly!
One of the hardest jobs in engineering is control of yourself! Really do all you can to stop yourself from cutting even the smallest corner. These things only cost you time and money in the long run. Even if it's a bitch of a job. Just bite down and do it better than you can imagine anyone else doing it ever before! You can turn even the crappiest job into a pleasure when the end result is perfection!
Good luck and let us know how you get on!
My guess is valve guides, but I would still pull the barrels while you are this far. ;)
Regards,
Julian
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Very wise words Julian, worth a karma.
Mike, don't like the sound of milky stuff. Probably just the oil and thinners emulsifing (bugga if I can spell that). But it should take quite some time for it to reach the sump. I got money on a ring. If you didn't take the rings off the piston and check end gap and one or more were too big they will break.
I use the hose clamp method but also use a bit of poly pipe cut long ways between the clamp and rings/piston. With lots of oil and tighten clamp till it JUST spins. Very carefully and slowly.
I do feel for you, I know what it's like.
Cheers
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im going to assume the milky stuff (wasnt that much) was exactly that; the emulsified oil and solvent. i am not going to go through with testing it as it stands with the 30 weight non-detergent oil. i have decided, after hearing what you guys have been saying, to strip the top end and look at the valve guides and inspect the piston rings. one reason i am optimistic about actually having this bike on the road this summer is that, starting tomorrow afternoon, i am on a 9-day vacation. surely enough time for a slow guy like me to get my act together, find the gaskets and other parts i will need and get this thing done.
by the way, from the start, i've been very slow and methodical about what ive been doing. not only because this is new to me, but because i value this machine for its history, engineering and beauty. im only 35 years old which is probably young enough to be a son to many of you, but my appreciation for BSA and its roots as a small group of gunsmiths at the dawn of the industrial revolution cannot be overstated. i have read extensively about the company and all it produced and decided i wanted to own something at the top of the A10 line.
8 years ago while riding with my vintage bike friends, i told one of them my dream of owning a super rocket. back then, i had an A50. i thought if i found one it would either be in such good condition it would be too expensive for me to buy (mortgage, wife, kids) or if i found one within my price range, it would be a basket case. i had to sell both the 69 A50 and a 76 honda CB550F in order to buy this and i couldnt be happier. i feel connected to this bike.
i have reached a point beyond frustration and impatience. i am calm and relaxed and ready to do what i need to do (with the help of a few drinks) to get this final stuff done right.
thanks for taking the time to help me through this, and i will post my results, hopefully within a week.
mike.
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Good luck Mike,
Your SR loves you, for loving "it" be assured ;)
I am sure you will get a lot of pleasure from riding it when sorted and all that hard work will pale into insignificance compared to the smile on your face as you blast down those country lanes!
Julian,
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Sounds to me like you'll have a very happy relationship with this bike ,really great to hear someone a lot younger than , i suspect, most of us here , who loves this marque and it's history. Beware they get under your skin and end up being a part of your life, which in my case stretches since I bought this bike ( most of it ) when I was 16 yrs old ,I'm 62 at present and still get the same buzz when I start her up ,wife says I even walk like a 16 yr old again ,( don't go there Musky ) so there's an additional incentive to you to carry on with it , built in eternal youth, well partly true even if its only in my head !! The very best of luck to you with your endevours BobH
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Had a little chuckle there Topdad-
Nice words mfhutchins-Mike.
You're not much older than my older one, and I'm trying not to deter him with my cussing and stuff- he looks at me kind of funny sometimes!!
One thing I've learned over the last year or so is that, just when I think I know something, the 'rules' change!!
Soon as I'm in the right mind-frame I'm going to post re-checking your gudgeon/wrist/piston pins bushes for square/true, so keep that in mind!!
Good on you for "havin' a go' as we say here!!
Cheers duTch
Just one thing-When I was at school I thought the industrial revolution was much earlier than BSA starting point,mid1800's?? maybe that's why I failed history-always learning.
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Dutch, I just found out that you are right about the industrial revolution. I guess I was referring to the technological revolution, which happened right after that from late 1800s to WWI.
How does the expression go? Older and wiser?
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One thing I've learned over the last year or so is that, just when I think I know something, the 'rules' change!!
Made me think of my own little expression, "Experience is; Remembering that you've made that mistake before, just after you've done it again" *smile* *smile
Julian
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I'm trying real hard to not be side-tracked from topic, but at least this one's Mikes'.. Maybe I didn't do history to have a chance of a mark??
Julian- I've reluctantly started looking at the instructions of things..But the writings gotten too small to read!!
And we still haven't got Mikes smoke issue sorted, and only have 9 days minus 2 to sort it....=7 (scraped through maths)
Cheers fer now
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ok so i just started to look at things before i pull the head. since i dint really know what to look for, i wanted to post a picture of what it looked like when i pulled off the left header pipe.
there was some oil on the valve stem. normal? there is a grey powdery coating on the guide. normal? also there was uncombusted fuel in the header pipe hole. normal?
any advice as i continue to remove the rocker box assembly?
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G'day Mike,
that looks pretty much normal. I would think if it was a guide/valve problem it would be inlet, allowing oil into the comp chamber.
Did it smoke like Lorenzo's bike *eek* ?
Hay BobH, I only said to the wife the other day that when I ride I feel like a 21 year old. She said I'm lucky to have the +50 year old I've got. *smile*
Cheers
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ok, inspection covers off and noticed that there is zero tappet clearance on the left side. i must not have screwed that nut in tight enough. maybe i messed up the valve adjustment. its only my second time doing one.
i will keep dismantling, but could this cause the smoking ie. allowing valve to not close sufficiently?
there is clearance on the other side but i have not put a feeler gauge to it yet.
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Doubt that would cause the smoke. Would not take long to burn a valve and run like poo. Keep diggin'.
Cheers
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I feel your pain mfhutchins, When I got my '61 Super Rocket I sent the motor to SRM for numerous improvements and after assembling the bike very carefully, after 500 miles I noticed a knock in the top end, turned out to be a spun little end bearing, done by SRM, they fixed the rod after I removed it and sent it to them, after reassembly one again the performance went bad after another 500 miles, turned out to be SRM's 357 cam had worn flat, "we had a bad batch, send it back to us and we'll replace it"....another dissassembly and reassembly. After 11,000 miles SRM's special timing side conversion bearing went bad, I sent it back well out of warranty with a curt note saying I had expected this bearing to last longer than 11 K, and they sent me a new bearing, and yes one more dissassemble and reassemble. All this wouldn't be too bad if I lived in Aberystwyth Wales, I live in California USA. All that being said I have gotten quite adept at tearing down and reassembling A10 motors.
Bottom line is you probably should start by compression testing, then removing the rockerbox, make sure there are no broken valve springs etc, if all looks good then remove the head and finally the barrels, you could do it in an afternoon, and in my opinion it's worth it for the peace of mind. I know full well the P'd off feeling you have, have a pint, put on your favourite tunes and go for it.
Good luck mate
Clive
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found: bent exhaust pushrod & fine, hairlike metal stuck to left valve spring.
still digging...
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Hi mfhutchins, so zero, tappet clearance ,coupled to bent pushrod on the same valve , doe's that valve move at all ? I had a similar experience when I'd just rebuilt mine despite completely renewing everything via SRM including the sludge trap and throughly cleaning system some debris managed to find it's way to the rockerbox and blocked the oil feed ,when I stripped the valve it had kissed the piston no visible sign of damage until I pulled it out very tight but only really visible when place on a flat surface with the old valve next to it ,it was well bent so thats what's my money's on, whizz the head off and check everything but start with that valve .Best wishes BobH, ... Musky ,from the sounds of things your wife and mine would get on ,thank god you're in Oz I'd hate 'em to compare notes , cheers bob.
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ok, so the piston rings look fine.
since i dont have a valve spring compressor, how am i supposed to check the valves/guides? i did the simple test where you pour fuel into ports and watch for leaking through the valves and there was none.
in fact, everything ive taken apart so far looks fine except for the bent pushrod and the mystery fine metal shavings.
one final thing i can think to do is check the ring end gap. any good methods for doing this?
could the smoke have been caused by just the bent pushrod and zero valve clearance?
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G'day Mike,
The only way to check the valves is to remove them. A spark plug socket over the keeper and a sharp blow with a knockometer usually dislodges the collets. You will need a vs compressor to assemble. A quick lap with fine grinding paste will tell if it's bent. Should end up with a nice even 1-2mm mark on the valve and seat. Check the top of the guide and underside of the keeper for evidence of contact.
Look for marks in the bores. If any the barrels off and rings off. Keep them in order. 10 -012thou gap.
Sorry for being short, off to work.
Cheers
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Bent push rod..... sounds like this was not properly fitted into the rocker cup as the rocker cover was mounted onto the head. Use the special BSA comb upon reassembly or be very careful that everything is sitting properly. Shine a torch in the tappet covers when everything is assembled as you turn the engine over and make sure the tappet cups and push rod tips are properly fitted. Check all the tappet clearances a couple of times during two or three rotations of the engine. Set the tappets by the 'one down - one up' method; i.e when one exhaust tappet is down, the other is up; same for inlets. If your rings are new I wouldn't worry too much about the end gap, people measure the end gap to give an indication of wear. I've seen engines run perfectly well with large end gaps, in excess of 0.025". If you really want to check you'll have to remove a ring and put it square in the bore using a piston to push it down. In old bores you would check the end gap at various positions down the bore to measure bore wear rather than ring wear.
Look very carefully for shadows in the bore i.e areas where the rings are not making contact with the bore surface. This would indicate poorly bored cylinders but should also show up on a compression test.
Valve guide wear.... buy a spring compressor! There's no way round it and now you have the head off it would be daft not to check this before reassembly. Also, as stated in Topdad's post you need to be sure that all the valves slide freely in their guides. At this stage it would be wise to check all the oilways are clear by blowing through the rocker feed pipe.
Just seen that others are posting at the same time, sorry if i've repeated anything.
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a friend of mine has a valve spring compressor that i will be borrowing tomorrow.
i definitely did not use that method to set tappet clearances. i will going forward.
should i bother with the ring end gap? my thought is that one or more rings may be too long??? how likely is that?
no shadows in the bore.
should i throw the valves/guides in the oven to check for free movement when hot? i am assuming when i check them cold they will move freely.
if the valves are fine tomorrow, am i to assume that i should reassemble the engine and hope that (1.) a ring doesnt break this time around (2.) i need to ride the bike with the 30 weight oil and let the rings bed into the cylinders and see if that alleviates the smoke issue? ...or was the zero valve clearance/bend rod the issue?
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Hiya Mike,
You're doing well, there's a lot of info there, 'zero gap' in my mind means half way between 1thou gap, and 1 thou over tight, and if it was more than that for some reason like the push rod has been misplaced, maybe there's a chance that the 'spring collar' is pounding into the top of the guide? That'd maybe produce swarf like that, and a bent rod??
Your own spring compressor is a good investment, and don't lend it, I did and it ain't the same.
Cheers for now, one thought at atime, and do as the others suggest
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G'day Mike,
do I read right in that the barrels are off? "(1.) a ring doesnt break this time around" Check the gaps. As Beezermacc said a large gap will still work but no gap won't.
If the valves slide good cold they will hot as the head & guide expand more than the valve stem. Were there any marks on the top of the valve guide? When they are loose they ride up and get clouted by the underside of the keeper. To check if any are loose (they won't feel loose cold) place head in oven (wait till wife is out) *smile* at 100c for 1/2 hour. Place upside down on blocks and give the guides a light tap with a timber dowel/file handle/curtain rod and mallet. If it moves replace it with a 1 thou oversize guide. At 250c they will almost fall out. If you need to replace one the valve seat will need to be cut and naturally all valves lapped in.
You'll be an expert in no time.
Cheers
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ok. now that ive removed the valves from the guides, how much excess play should there be?
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here is what i found on the left side.
since there were no issues with the right cylinder, i dont need to bother with it, right?
what is it exactly i am looking for? there are little black marks on the exhaust valve and seat in the same places. you can see in the pictures the black scoring. i have no idea what it is or what caused it. maybe the valve wasnt seating properly due to poor lapping? i am on the right track?
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Maybe not seating due to tight adjuster?? How's top of guide/bottom of spring collar??
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after 30 mins. in oven at 215f with a light tap on each valve guide there was no movement.
the lower spring collars fell out after i turned it upside down.
can i clean and reassemble?
im thinking it was the tappet adjuster that was too tight not allowing the valve to seat completely (and bending the pushrod).
the bend in the pushrod was barely detectable. so it must have been just slightly overtight.
also, i looked at the cam lobe that probably had constant force upon it from the bent pushrod and there is no sign of wear. it still looks brand new.
i will wait to reassemble once i get some feedback when australia wakes up.
thanks!
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Yawn, 5:30am I'm up.
Looks like the last time apart the seat was cut but not lapped. Guides sound as if their in tight enough. Put valve in and lift about 3/8" off seat, you should be able to wobble the valve fore and aft about 1/2mm, any more than 1mm is too much, valve guide liners are an alternative to new guides. Now give all the valves a lap, the bad one might take a bit. Check that all have a nice even lap mark. If the bad one's lap mark is thick then thin it's bent.
Push rods don't usually bend by themselves. Something came into contact, either valve/piston, collar/guide. Over adjusted tappet could be at fault but not the only thing eg turning motor over with the timing marks not lined up etc. Do NOT reuse a bent push rod or valve.
The lower collars will push back on.
How do the ring gaps look?
Cheers
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Revelation! I just discovered after removing the right hand valves, that the left exhaust valve guide has been worn. As evidenced in the attached picture, the inside diameter is significantly wider than that of the other exhaust valve guide. Time for replacement.
Maybe this was it?
there is also pitting around the end of the guide. not sure how that happened. all 3 others look fine.
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just removed the problem valve guide and it measures .630 O.D. where it sits in the bore. this is oversize, correct?
british cycle supply in nova scotia told me the correct O.D. is .560.
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G'day Mike,
that sounds like a dodgy one. She must have had a problem and munched the hole at some stage. The chamber looks a little poch marked on that side, may be pinging. The alloy head should have bronze guides but have heard that BSA did use iron guides for a time.
I have the same problem with an old '54 twin carb head. Will have to make a special. When you get one made, make that bit 1 thou bigger (0.631") and the bore a tad small and ream once fitted to suit the valve. Just about any engine recondition shop would be able to do the job.
Yes that may well be the smoking problem.
Cheers
Bugga done my money on the ring theory.