oil consumption

Hello all,
I have a 74 850 mk 11a which has used 3/4 of a tank of oil in 300 miles. Is this a lot.
The reason I`m asking is when I start it up, smoke pours out of the left pipe followed by the right pipe some 10 - 15 seconds later. The later one seems to be when the oil has reached the valves then it gets sucked into the barrel. This would be the valve seal gone yes.
There will be some wet sumping as I usually only ride it once every 2 to 3 weeks.
After about 50 miles, when its nice and hot, both exhausts will smoke when on tick over. When revved it seems to clear itself, but comes back again almost instantly if left to tick over. Its hard to see any smoke when its being ridden.
Apart from that it runs fine, and even though the sparkplugs are a bit dirty I don't have to clean them.
It doesn't tick over very evenly or reliably. It will be great all day but as soon as you brake hard with the clutch in it usually stalls. Now I don't know if its the extra oil in the barrels that effect this but it cant be helping. Both carbs are less than 3 years old and are set up ok.
Any ideas, as I`m reluctant to disturb an oil tight engine. But, when people start coughing and running for air it gets a bit much.
Many thanks
chris r

3/4 tank in 300..thats excessive..no leaks so its burning it, guides or rings...its a strip down.

blacklav said:

Hello all,
I have a 74 850 mk 11a which has used 3/4 of a tank of oil in 300 miles. Is this a lot.

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'74 Interstate with over 12k miles, and it burns 1 pint about every 1000 miles. Like John says...

Nathan

Thanks for the replies, I sort of was expecting a strip down, and in a way I wanted to do it as winter is almost here.
Can anyone recommend a good cylinder head shop in the UK, in case the valves and guides are shot.
Many thanks
Chris r

blacklav said:

Thanks for the replies, I sort of was expecting a strip down, and in a way I wanted to do it as winter is almost here.
Can anyone recommend a good cylinder head shop in the UK, in case the valves and guides are shot.
Many thanks
Chris r

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Hemmings, Norman White, D&M....where are you?

Mick Hemmings did my rebore and head work (i splashed out on a big valve job) he also did crank regrind and assembled it after dynamic balancing. He has a large stock of top quality old stock AE pistons and other parts. He gives honest advice and doesn't push you to have thing done an with his knowledge an reputation you feel you are in safe hands.

Immediate smoke implies wet sump splash getting past cold piston rings and takes 15 sec or so for head oil to flow in and pressurize, which implies valve guide elements. To loose that much oil so quick would imply fogging clouds behind you so maybe also a hidden leak being blow away too. Could also just be rings not seated well yet so a job for Bon Ami before major surgery again.

Steves right ,that amount being "burned" will have a constant hazey smoke trail, two strokes dont use that much! a good cylinder/guide engine should do 1000 miles with the level dropping 1/4 inch? some go between changes without adding top up.
Surprised the plugs dont protest ,very hot plugs may just burn off the excess :?:

What is the history of the motor... Have you had it apart before or did you inherit a non oil leaker .. Clearly, at least valve guides/seals require inspection as they could possibly soley lead to your hazy problem. When the head is off and fiddlin and pokiin "as we do" you then pull the barrels off, your Norton will be changed forever for the better..
If you dont know the history of piston and rings then you would achieve significant empowerment if you took your wife/partner away for a weekend make her feel very special, (just because your a great guy) "before" you start to "fully" recondition the motor.. :lol: :lol: :lol:

I have read on this forum that smoke on tickover implies valve stem oil seals which can be checked without removing cly head, I've had them fail and there was a fair bit of smoke at low revs, but maybe you've checked already.
J

olChris said:

if you took your wife/partner away for a weekend make her feel very special, (just because your a great guy) "before" you start to "fully" recondition the motor.. :lol: :lol: :lol:

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I find as doubtless many other do that my wife has no interest in my hobby and as such no idea of the costs involved. So as the old saying goes "ignorance is bliss" her blissful ignorance that is :lol:

toppy said:

olChris said:

if you took your wife/partner away for a weekend make her feel very special, (just because your a great guy) "before" you start to "fully" recondition the motor.. :lol: :lol: :lol:

Click to expand...

I find as doubtless many other do that my wife has no interest in my hobby and as such no idea of the costs involved. So as the old saying goes "ignorance is bliss" her blissful ignorance that is :lol:

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Has she got a single sister?? :lol: :lol: :lol: (only joking)

How about her mum, me being 60 that is.
Thanks for the replies, I`ll ring Mick H up when I get the head n barrels off this weekend.
The motor was rebuilt by the previous owner 7000 miles and 3 years ago, not a lot. It always smoked a bit but has just got to the point when something has to be done.
chris r

Had similar smokage. Valves guides were loose in the head from a number of garage home valve jobs over the years. I think only a handful of people in the world really know how and can do this job right.

Ta.

Wesley and I are now experts on ring wear with 15 yr of comparing notes for identical finding in Commandos, hi end motorscooters, lawn mowers and tractors, they will all smoke to hi heavens till so oil fouled will not fog further yet never used the oil amounts in this instant case. Being a seasoned Cdo owner now I'd suspect both some rings wear and maybe primary engine oil leak too. Being a seasoned Cdo owner I know what's next and then some more. I have a work for the mood.