When I take off quickly in first, from the lights, I can notice a puff of smoke.
Also, when I am running on back pressure, e.g. down a hill, and then I accelerate it blows smoke.

Apart from that I can not notice it.

What do you think could be the issue?

I have been advised it is the rings but not to worry until it gets worse. I'd prefer to fix it rather than be reported, although it is good for tailgaters.

I have been searching but not found an obviously related issue.

Thanks in advance for your knowledge.

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

Could be the valve stem seals.
If you are driving, does it blow smoke constantly or only under load?
Does it blow smoke ONLY when you start at the lights and down hill or when cruising?
What colour is the smoke?

Is it just smoke or does it feel like its missing too?

There are other posts about this, one recently, look up smoke rings valve ine the search


Especially this one:
http://www.ausmini.com/forums/viewtopic.php?t=24321&highlight=smoke+rings+valve

Cheers,
Peter

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Click here for the Turbo Conversion Thread!

yea....from your description it's valve stem seals me thinks.

When I back off....then accelerate it blows a cloud then it seems ok.

colour is blue.

engine runs fine. Plenty of power.

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

hmm, I reckon its the valve stem seals... did you read through the link I sent?
Try the last post as advice...

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Click here for the Turbo Conversion Thread!

Yep have read that post.
I will try the rev test this evening at work...my neighbours don't appreciate the sweet sound of a large bore mini exhaust...

I did a compression test a few months ago (no more than 1000Km's) and had ~150PSI across all 4 cylinders.

I'll advise the outcome of the 3k test later tonight.

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

Remind them they have every right to move You'll help them pack
You can be noisy until 10pm I believe (depends on area, etc)

Im good to my noisy neighbours (they party alot) ... I only snap if they wake the baby... then I let them know it aint on.


Peter.

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Click here for the Turbo Conversion Thread!

There is a couple of diagnostic characteristics here.

Smoke from worn rings will occur at lights, under load and with the application of throttle at the bottom of a hill or a period of trailing throttle. Slight smoke can often be seen at any rev range.

Valve guide wear is characterised by smoke at take off or after periods of idle but then clears.

The only clear way to accurately test for rings is with a compression test without and with oil in the cylinders.

Don't rush into a remedy unless you are rich. It means an engine strip down and costs. Mini almost never allow just a re-ring. The bores almost always wear tapered and require a rebore and oversized pistons - there is $400 just for that !!!

The thing with rings is the compression rings can be Ok but the oil rings can be shagged, this means the compression will be fine on the gauge but it will still blow smoke.

My guess is the valve stem seals. The standard seals are crap and will die quickly.

I'll try the with/without oil compression test tomorrow...dependent on whether Brisvegas gets the forcast rain.

I'm not rushing for a solution...but changing valve stem seals is simpler than a rebore

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

Yes - it a lot cheaper but I think you will find its valve guides rather than valve stem seals. But .... for about $250 you can have the guides, seals, chemical clean, surface skim and .. best of all ... unleaded exhaust valve seats al the valves reseated.



.

The current head was rebuilt 2.5 years ago. Less than 7500 Km's ago (A guess as tacho doesn't tell me how many km's I have travelled). Hardened seats were added then. I expect that the guides were replaced then, along with new valves and iskenderian double valve springs.

Mind you the head had a crack welded (it only had one crack the previous head had three).
The car had buggered twin 1.25's rebuilt the start of this year and 43d4 distributor recently improved to pertronix.

Has been tuned and runs better now.

could being out of tune, with too much advance have caused the smoking issue?

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

Ummmm..... probably not caused by poor tuning.

There are valve guides and valve guides. Some of the cheaper ones have a very fast wear rate. As a rule of thumb, its prbably better to buy a set of good competition type valve guides such as off a mini metro turbo or maganses bronze type.

When you ultimately take the head off - without the valve springs in place, if you can move the valves from side to side in the guides then the guides are worn. It only has to be perceptable movement for the oil smoke to show.

I have no doubt the seals have worn - the rubber cup type are infinately better than the "o" ring type, however, worn seals and good guides will not give the smoke that is being described.

OK tried the 3k rpm test... unfortunately it was a bit windy so I'll try again with an assistant.

I didn't notice any smoke when rpm held at 3k. Although I could notice smoke when I pulsed the accelerator...which from consensus points to valves...

More testing tomorrow

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'72 clubbie, 1360,twin hs2,loud.- and currently broken
'06 Ducati Monster S2R 800

try a thicker oil

what are you running now?