Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Still burning oil - considering parking it

A while back I posted in regards to the oil consumption by my 68 Spitfire. Well, I tore into the motor and verified that the breather is intact and functional. I replaced the seal behind the alternator rotor, had the cylinders measured and honed, and fit a new set of Hastings rings, new head gasket, new Champion plugs, and filled with 30w mineral oil (Joe Gibbs Driven br-30).

On start up, the prognosis looked good. I was able to set the timing quickly and headed out for a quick warm up ride. I noticed a bit of smoke when taking of from a stop but assumed it was all part of bedding in the rings. As I rode the smoking on the right side became especially noticeable on closed-throttle deceleration. Within 15 miles, the right plug fouled and the bike started sputtering really bad at higher rpm (over 3500). Put in a NGK plug I had on hand and started heading back. Within a dozen miles, the NGK plug started fouling.

I'm so frustrated that I'm thinking of draining the fluids and parking it in a corner indefinitely.

If not a crankcase pressure or ring issue, what else could cause this?
What else would cause an issue this bad on only one side (plug on the left looks perfect)?
Too much oil pressure at the head? (guides and valves were done last year)
A plugged up oil tank vent?
A right-side rod with the oiling hole? (unlikely, since Carrillo rods are used)
Leaky head gasket? (head and barrel were milled last year, but maybe a bolt is bottoming out)

I'm looking for any simple thing I might have overlooked, because if I have to pull the jugs off that thing one more time it's getting turned into a couch in the corner of my basement.

Smoking on deceleration usually means the oil is coming down through a valve guide. The valve guide or guides could be worn, or oil return passages are blocked such that a lot of oil is pooling around the valves.

Most likely oil is seeping between the outside of the valve guide an the head.Either intake or exhaust guides can do this.It's normally caused by removing dirty guides without cleaning them first,and damaging the head in the process.
The smoking usually becomes noticable about a minute after start up.

You can use some sealant under the valve spring seats and around the guides,to stop oil leaking through the head.

Did you use sealer around the drain holes in the head gasket? Composition or copper?

Hi

When you check the exhaust valve oil drain holes are not blocked, have a look at where the drain starts in the head, I've seen some which are quite high. This can cause the oil level to be high before it even start to drain. In the past I've used dremmel type tools to lower the drain point to the bottom of the spring chamber.

John

I'd say valve guides. I found my only to smoke whe pulling way from a standstill when the guides were worn.

I'd send the head away and have it properly overhauled. Saves trying the small stuff and wasting a lot of time.

Another possibility, if the oil pump is leaking at the join it would probably wet sump after a while but also it could pump/spray oil into the T/side over oiling the R/h piston. The case has a deflector I imagine to restrict the oil coming out the bush over oiling the R/H bore, more oil getting thrown up could cause smoking like when they wet sump but primarily it would effect the R/H cyl.

Thanks for the input. I guess I'll be taking the head off tonight and checking the drain holes. I don't have a tool to remove the valve springs so I'll have to borrow one.

The things I've done, related to the head, to try and address this are (it's been ongoing for a couple of years):

Valves and guides replaced (done professionally which, I assume, means done right)
Head and barrel resurfaced
Head gasket with and without o-rings
Head gasket with and without copper sealant (the spray-on copper coating)
Motor with and without oil filter (head oiling was bypassing the filter)

Is there a simple way to eliminate the guides as a potential suspect? I don't mind the smoking (within reason) but the fouling spark plugs makes the bike unrideable. As I mentioned before, I'm so frustrated with it that I'm no longer willing to keep trying things at random, then parking it for a month when that fails, then trying something else. With the money I've spent on this thing without success I could have probably picked up a nice Ironhead Sportster project.

The only thing you did not mention is what grade of plugs you were using.
Modern fuel ( which is not petrol) usually requires a hotter plug, up at least 1 grade if not two .
I had a funny one on the way back from the (Aust ) BSA national rally, on a long fast sweeping bend I backed of the M20 ( so timing would have been wrong ) for about 300 meters and when I reopened the throttle, nothing motor was stone dead.
We did not look at it just tossed it onto the trailer. Problem, fouled plug and that was after about 300 km so it & the motor were quite hot.
Smoke on deceleration is generally oil being sucked into the cylinder ( as already mentioned ).
It can be coming down the guide or around the guide or even through a crack and I have even seen one sucking oil from the head gasket

my newly done A10 motor did similar ... really drove me nuts ... eventually I determined that the wonderful NEW rings (oil) were actually out of round and not scraping the oil off the cylinder properly ,, I determined this because there was no other explanation and the bike was going real well.


... rather than tear it down again I just decided that I would get some miles on it first and see if it improved ... it gradually started smoking less but continued to foul plugs (after 800 or so miles), man I was pleased I has a gas torch to burn the plugs clean rather than buy new ones every time ...recon I would have literally used 40 plugs!.. like every time I went on the A10 I took 4 plugs and a plug spanner.

I put in NGK number BH5 (a way hotter plug) and at least he fouling has stopped (touch wood)

If I were you I would try 2 grade hotter plugs first and see if that helps.

Clean around the top of the guide with brake cleaner,and put some silicone sealant around the guide under the spring collar.

While you're in there,sharpen the tops of the guides like a pencil (about 120 degrees included angle) to remove any chamfer on the guide bores.A chamfer will collect oil,and the oil will leak down the guide and valve stem (which you don't want).

You wouldn't be the first one to have guides professionally replaced,but leaking between the guide and head.

It's funny you mention that because that's what I've told my wife: except for the smoke, man that bike runs good.


I've tried Champion N3C and, most recently, N4C but I believe that's actually a colder plug. I'll need to research that. The NGK I ran temporarily on the right side was the B8ES.

I'm thinking one I get the spring out I'll plug the drain hole and fill the cavity with Marvel Mystery Oil; not high enough to go down the guide, but it's thin enough that if it's leaking there it will show.

On a related note, I can see that the exhaust valve will be dirty from the burning oil even if it's not the one leaking. What about the intake valve? I'm assuming if it's not leaking the valve will be relatively clean. Am I mistaken? Is there enough overlap from exhaust to intake that it would dirty the intake valve as well?

If it is the guides or a crack in the head maybe what you could try, is temporarily stopping the oil supply to the head by clamping the rubber feed tube. Don't do this for more than a minute or so or damage may occur. With the oil feed suspended, if the smoke reduces then this shows the problem is related to guides or a crack in the head.

IM also wondering if you have the rocker box oil feed reducing split pin fitted? This should be visible just after the rocker oil feed inlet and is designed to reduce oil supply to the rocker box.

Some other areas to think about:-
- although you have new Hastings rings, have they bedded in and what plateau finish was used on the cylinder walls? When running in there is a small window of opportunity to get it done, immediately after first start-up. The procedure should be a to run the bike up a steep hill several times with a big handful of throttle. This procedure causes high cylinder pressures and forces the rings against the cylinder walls resulting in a good seal. Anything less such as idling for long periods before a good blast may cause glazing, a poor seal and high oil consumption.
- I wonder if your sump is filling with oil and not being completely scavenged? I recently had a similar smoking issue on my A65 which was cured after I drained the oil from the sump via the magnetic drain plug. I found the magnet to be completely covered with ferrous sludge which may have obscured the oil scavenge. Its also possible that the magnet prevented the scavenge ball valve from fully opening.

Anyway just my tuppence worth.

+1 for rings not seated, or bent during installation.

The reason I'm doubtful of rings is that this is the third or fourth set of rings since this all started (I lost count) and that I'll never be able to get them to seat if the plugs foul out every 15 miles. There's no way that's normal for bedding in rings.

my added thoughts to the good advise given ... When piston reassembly, insure you are not slathering both with oil. If you do this some of the oil is trapped between the rings which bakes to a sluidge or carbon 'glaze' preventing proper ring seating.

Always insure you are correctly fitting the rings. John Healy had a good explanation of this in a recent issue of the Vintage News. All of us need to subscibe for the important tid bits of knowledge you'll pick up in this great publication.

The correct assembly procedure is to lightly oil the bore and then with a clean 'dry' cloth wipe as much oil off the cylinder as possible. With the rings dry smear a small amount of lube on the the piston skirt.
Then follow Gunners correct advise on breaking in. Do Not allow the newly assembled engine to idle too long on first start up thinking you are 'being kind' to the engine.
These are merely not my ideas, but proven by many many engine builders. Do it right and you'll never have a wiff of oil smoke in the exhaust.

MarcB
man that does sound excessive... if you've had 4 sets of rings in there then perhaps the bore itself is not 100% true ? does the bore show any uneven wear pattern ? In the case of out of round bore you would get longitudinal "sections" which differ in "pattern" ie you might have a stip(s) with is more shiny than the rest or strips that show more of the honing pattern ?

the only real way to tell is do a series of accurate measurements looking for ovality. And or put piston and just oil rings into bore and shine a real strong light under it ... if you can see light there's your prob, repeat with just one comp ring on no oil ring etc

what is the compression like hot? how many mile total has that bore done, since a rebore not just a hone?

sorry to say but 4 sets of rings in one bore (even if honed between sets) does raise alarm bells

it does sound worse than what I described with my A10 as at least with the problematic A10 once it was up and running it didn't foul , one run was 180 miles without incident and $%^%&*ing thing fouled on start up the next #$%^^ing day

still recon way hotter plugs is worth a shot, and way easier than another pull down

a valve guide would need to be REALY bad to cause the problem to the extent you have said

There's a very good (but long) thread discussing rings, honing and break in procedures, see This Link , hopefully reading through this should help you find answer to your oil consumption problem and it certainly has some good advise.

My

As I mentioned some weeks ago I found some damage to my piston bore ( left pot) from cold it ended up consuming so much oil it looked worse than a 2 stroke, and the more miles I did the worse it got, it had consumed about 2 litres of oil over 200 miles!!! Once warm it didn't burn any more and ran a lot cleaner.

Anyway for various reasons I got another barrel instead of having mine rebored. Not done any mileage as such yet but there is no smoke at all now.

It's worth mentioning that too rich of mixture can wash the bores clean and give premature bore life, using the wrong grade of oils ( those with friction modifiers) will glaze the bore before the rings bed into it.

Your smoke, it it blue or black (/grey) ?? Blue is oil, black is rich fuel mixture.

Using the wrong grade of plug is no cure for anything, using something like an N5 where an N3 should be fitted is not going to fix the problem, it might burn a little cleaner... It might also cause pinging and poor running. I've found poor running first off, and never give it chance to ping.

To cure the problem you need to fix the problem. Take the head off, send the pistons to BDC ( bottom dead centre) and look at the bore in the day light, what colour is it? Uniform grey ?- then it's run in well and don't touch it.
Straw coloured yellow? - then that's glazed my friend and all that yellow is baked on oil, you need a hone in the least and possibly new rings.
Are the rings good?? Do they show signs of buring, or any other markings?

If the bore and rings are good, check the head gasket surface is flat with a (good and clean) steel rule. Both these are known to warp. If those are good the it might be time to look at valves and guides. A good cylinder head shop can do wonders :bigt

I'm not exactly sure what you mean by 'sump level will be high'. How do I check this, and how high is high? I've never drained more than, I don't know, a cup out of the sump. Usually a bit dribbles out after the plate breaks loose, then whatever is left in the plate makes up about a cup, I'd say.

Would wet sumping affect the right side more than the left? I'm guessing that's possible since the oil flow terminates on the left so that side may be designed to expect more oil that the pump side.

I will say that the first few times I've ran the bike low on oil I fully expected to drain a quart or more out of the bottom end. But that never happened. It was all lost to the atmosphere.

Oil leaking around an exhaust guide can get sucked into the intake port during valve overlap,especially at idle when there is high vacuum in the intake port.
Just seal all the valve guides.

Just in case you're still looking for that valve spring compressor here's one I made earlier....

(Note, remove corks from all required bottles of wine before starting!)



Cheers,
Bernie

Ha! I've used tools to open up bottles in the past, but never the other way around.

Allan Gill ..."Using the wrong grade of plug is no cure for anything, using something like an N5 where an N3 should be fitted is not going to fix the problem, it might burn a little cleaner... It might also cause pinging and poor running. I've found poor running first off, and never give it chance to ping. "

All I can say is that using 2 grade hotter plugs has stopped them fouling on my A10... it is running very well and very slowly the rings are bedding in and the smoke is lessening, infact it has almost stopped now with a couple of additional reasonably long runs. Mind you the A10 is only 6.5:1


Bernie... your a genius... looking for that cork screw as we speak, I take it you are just using a long piece of bar or similar held in the chuck to bear on the valve head?