Author Topic: smoking super rocket  (Read 6193 times)

Offline mfhutchins

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smoking super rocket
« on: 22.06. 2012 02:34 »
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




Online beezermacc

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Re: smoking super rocket
« Reply #1 on: 22.06. 2012 08:25 »
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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Offline Flatboy 1950

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Re: smoking super rocket
« Reply #2 on: 22.06. 2012 08:46 »
White smoke is NOT from oil burning !!!

Regards , Flatboy.

Online beezermacc

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Re: smoking super rocket
« Reply #3 on: 22.06. 2012 09:13 »
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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Offline mfhutchins

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Re: smoking super rocket
« Reply #4 on: 22.06. 2012 11:39 »
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?

Offline mfhutchins

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Re: smoking super rocket
« Reply #5 on: 22.06. 2012 13:04 »
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.

Offline a10gf

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Re: smoking super rocket
« Reply #6 on: 22.06. 2012 14:19 »
Quote
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.

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline wilko

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Re: smoking super rocket
« Reply #7 on: 23.06. 2012 00:14 »
Go back to rule one. Drain your crankcase before starting up, then see what happens.

Online bsa-bill

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Re: smoking super rocket
« Reply #8 on: 23.06. 2012 12:33 »
Quote
(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.
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline nagrod

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Re: smoking super rocket
« Reply #9 on: 23.06. 2012 12:58 »
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
'Never again. But that's what I said the last time.'


Offline muskrat

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Re: smoking super rocket
« Reply #10 on: 23.06. 2012 22:09 »
 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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Offline chaterlea25

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Re: smoking super rocket
« Reply #11 on: 23.06. 2012 22:12 »
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
1961 Super Rocket
1963 RGS (ongoing)

Offline mfhutchins

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Re: smoking super rocket
« Reply #12 on: 23.06. 2012 23:04 »
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?

Offline mfhutchins

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Re: smoking super rocket
« Reply #13 on: 23.06. 2012 23:12 »
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.

Offline mfhutchins

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Re: smoking super rocket
« Reply #14 on: 23.06. 2012 23:27 »
the pistons came with the rings already fitted.  although i inspected them, i am pretty certain none were upside down.