White smoke pouring out of exhaust pipes!

Classic Norton Commando Motorcycles.

White smoke pouring out of exhaust pipes!

Postby highdesert » Fri Oct 09, 2009 7:00 am

Hi everyone!
I have about 10,000 miles on my rebuilt head now, well new guides were fitted then, valves lapped, but all else 37 years old.
When I start it up, let it idle one minute, and then take off, white smoke pours out of the right muffler for maybe 10
seconds or so, then it goes away. I have been ignoring this. Now, the left pipe has taken over this job.
So, am I right to presume my valve guides are leaking oil in to the combustion chambers?
Gotta take the damn head off and send it out to be reworked?
CNW has a $1000 total head job, new everything, on their website. What you think?
Or maybe my rings aren't sealing?
Should I do a compression check first? What should it be, cold or warm motor for the test?
What do you do, kick it over a number of times and see what the reading is?
Or can this issue just be ignored, let it burn a little oil and keep riding it?
Appreciate all comments

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Re: White smoke pouring out of exhaust pipes!

Postby dave M » Fri Oct 09, 2009 7:25 am

Is your motor wet-sumping between rides by any chance? try draining the sump and putting the oil back in the oil tank before your next ride.

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Re: White smoke pouring out of exhaust pipes!

Postby MEHAVEY » Fri Oct 09, 2009 7:42 am

highdesert wrote: Should I do a compression check first? What should it be, cold or warm motor for the test?
What do you do, kick it over a number of times and see what the reading is?
Or can this issue just be ignored, let it burn a little oil and keep riding it?


On the compression check, "Yes." Kick it over a half-dozen times each cylinder so that you get the highest reading over that sequence. Do it cold, then ride it so as to do it again hot.

On whether you really care.... do are the plugs overly black/fouled as you take them out hot to do the second compression test? ...and are you really *consuming* oil as you monitor the oil tank level every coupla hundred miles?

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Re: White smoke pouring out of exhaust pipes!

Postby frankdamp » Fri Oct 09, 2009 8:17 am

White smoke? Most oil burning results in blue smoke. White is usually coolant with antifreeze, but that would be very rare in an air-cooled engine!
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Re: White smoke pouring out of exhaust pipes!

Postby DogT » Fri Oct 09, 2009 8:26 am

Leo Goff will do the head for around $4-500 depending on parts and I understand he is quite good. No experience with him yet though.

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Re: White smoke pouring out of exhaust pipes!

Postby ludwig » Fri Oct 09, 2009 8:34 am

If your oil consuption is exessive , it will show on the plugs .
Have both the same colour ?
what's your oil consumption ?
many Nortons will smoke a bit left side , when left idling on the sidestand .
frankdamp wrote: White is usually coolant with antifreeze, but that would be very rare in an air-cooled engine!

unless somebody peed in the exhaust ?

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Re: White smoke pouring out of exhaust pipes!

Postby highdesert » Fri Oct 09, 2009 9:25 am

Thanks for the comments.
To answer some questions:
I have a simple WOG valve in the oil line, I shut off all oil from the tank down in the driveway after a ride, so the motor runs another 30 seconds or so
before it is shut off, therefore the only wet sumping is from whatever oil is the timing cover draining. I don't believe this is a problem.

The plugs are not black or oily, they look pretty good. Both same color.

I confess that I do not regularly check the oil level, maybe every couple of weeks, the level stays pretty much in the middle of the markings.
However, it could be going down so slowly I just don't know it.

I will first take the suggestion of doing a cold compression check, and then a warm one. What is the acceptable compression number?

Does the compression check tell me if the rings are sealing ok, or does it tell if the valves are fully closed, or maybe both.
Any further tests to indicate more specific head or rings issues?

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Re: White smoke pouring out of exhaust pipes!

Postby Rich_j » Fri Oct 09, 2009 10:13 am

When you say the plugs look OK have you stopped the engine while its smoking or after you've had a run and burned the oil off? If you haven't done it, kill the engine while its smoking and pull the plugs.

You can eliminate rings very easily by disconnecting the oil feed to the head and blocking the banjo fitting with a bolt and copper washers, then go for a short ride, if problem is in the head the smoke problem will have gone away. The top end will survive happily without fresh oil for quite a ling time.

Have you got the rocker shaft flats facing the right way? If they've been installed wrong the head will get over oiled and give the symptoms you're seeing.
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Re: White smoke pouring out of exhaust pipes!

Postby daveparry » Fri Oct 09, 2009 11:05 am

highdesert, I also have an oil shut-off valve in the oil supply but wouldn't think of turning it off whilst the engine is running! In fact I couldn't as I have it interlocked with an ignition cut-out. I'm puzzled about your white smoke though, as said earlier this is usually water, oil smoke is normally blue wherever it's coming from,
Dave.

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Re: White smoke pouring out of exhaust pipes!

Postby boz » Fri Oct 09, 2009 11:27 am

If you have low compression you don't know if it is valves or rings. Take a teaspoon or so of engine oil and pour it in the spark plug hole kick it over a few times to coat the cylinder walls. If the compression goes up it's your rings. Stays the same its your valves.

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Re: White smoke pouring out of exhaust pipes!

Postby MEHAVEY » Fri Oct 09, 2009 11:37 am

highdesert wrote:Thanks for the comments.
I will first take the suggestion of doing a cold compression check, and then a warm one. What is the acceptable compression number? Does the compression check tell me if the rings are sealing ok, or does it tell if the valves are fully closed, or maybe both. Any further tests to indicate more specific head or rings issues?


Remember, at least a half-dozen kick cycles to max out the compression before reading.

Normal compression could/would range from 135-165 (it's dependent on a lot of things--including how macho you might feel that day) with both sides being near the same. If one side varies more that 10% from the other, then re-test/watch that side. (`Doesn't mean a major problem, but watch it over time.)

Vanilla compression tests will tell you the condition of the rings/valves combined. If found to be low, then squirt engine oil into the plug hole/chamber to effectively seal off the rings and run the compression check again. If compression goes up, you've isolated the problem as rings. If no appreciable change, then most likely valves.

But if you aren't losing appreciable oil from the tank in comsumption and/or seeing fouled plugs, fuhgedabout.

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Re: White smoke pouring out of exhaust pipes!

Postby maylar » Fri Oct 09, 2009 3:33 pm

Compression tests only give you a gross indication of overall engine health. A leakdown test is far more useful for identifying where problems might be. If you don't have a compressor and the special tool, find someone who does.

In my experience:
Smoking at idle or when blipping throttle, typically is intake guides and / or seals. But it doesn't go away after warmup.
Smoking under load is usually rings. That can diminish after warmup.
Smoking only after initial start can be rings or oil that's "puddled" in the head after your last run. try putting a 1-way valve in the breather line to the tank. Many times it works wonders.

And as for Leo Geoff, Memphis Motor Werks, I have this forum to thank for turning me on to him. Magnificent workmanship and a truly honorable fellow.
Dave from CT
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Re: White smoke pouring out of exhaust pipes!

Postby montelatici » Fri Oct 09, 2009 5:03 pm

Is it humid where you live and are there big temperature changes where the bike is stored? Sometimes condensation dampens the inside of the pipes and it burns off as steam (white smoke).
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Re: White smoke pouring out of exhaust pipes!

Postby highdesert » Fri Oct 09, 2009 6:00 pm

I live in New Mexico, VERY dry here, really low humidity, bike is a closed garage all the time

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Re: White smoke pouring out of exhaust pipes!

Postby Rich_j » Sat Oct 10, 2009 1:32 am

This stuff about blue smoke for oil is a bit confusing. I've had plenty of problems with oil and the smokes almost always been white.
I know for a fact that if you dump the contents of an oil system onto a hot exhaust the smoke is white.

Maybe it depends where the oil gets into the system. If it leaks past the exhaust guide does the oil actually burn or is it just vaporised?
it probably doesn't actually get into the combustion chamber.
It can only get into the combustion chamber from the inlet valve side, rings or head/barrel face leaks, does that make the fabled blue smoke?
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