Running in after rebore and new piston

Mtoliva said:
Ged at GCS changed the oil, I‘m sure he didn’t use synthetic oil.
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I'm sure he won't have. If Ged did the overhaul work then I'd speak to him - he's got plenty of knowledge and experience. .
You'd be very unlucky to have a piston ring problem occur simultaneously on all 3. Have you done anything with the air box or filter? Changed anything e.g. breather pipe? Made any adjustments?
 
I agree, it must be something equally effecting each cylinder, and yes I spoke to Ged, he suggesting checking out the ball valve in the oil breather, looks good to me, I haven’t touched or changed anything else, so a real mystery why this suddenly started to happen.

Could the gradual build up of oily soot in the pipes be something to do with the rich plugs? I can clean it out of the exhaust ends but would have to take the whole system off to give it a good clean?
 
Here is Stevio from 2005... maybe it helps.

On a few occasions recently problems involving swollen breather balls have cropped up so I thought it may be of interest to those of you who haven`t yet come across this little component.
The breather ball sits under the part that the breather tube pushes on to----it acts as a valve allowing air pressure inside the crankcases to escape;then when there is a partial vacuum inside the crankcases the valve closes and stops air being sucked in .
There is a tendency for the ball to swell up due to reaction with oil (some oils seem to cause it more than others but there are too many variables to be able to establish any "rule" ). The ball can swell to the point that it severely restricts or even blocks the venting of the crankcases. This causes an unwillingness to rev freely that may well not be noticed by most people---it also causes or exacerbates oil weeps /leaks. The internal pressure is in the crankcases, the cam chain tunnel and in the area above the valves. It will find any weak spots in the gasket faces,oil seals and castings (due to porosity). If you seal one weak spot the pressure will find the next weakest point. Quite often it results in a few damp patches rather than one distinct leak.
The ball is easy to get at (stab it with something like a hat pin or compass point in order to lift it out). There is a simple test which is to drop the ball from shoulder height onto concrete.------It should only bounce an inch or so off the concrete if it bounces any more than that it needs replacing. Sometimes boiling it with a little washing up liquid in the water may provide a temporary cure whilst you organise a new one.
It is not a good idea to leave the ball out as this allows air in and builds pressure.
The last of the 120 degree Triples were fitted with a shuttle valve ---they can be easily identified because the housing is different.
 
Paul Marx said:
A blocked breather will push oil out, not in.
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Indeed..but where will it push it??

Chuck the breather ball away.
Or, if you're not made of brave stuff, remove it and see how the bike runs then. Back in the day, received wisdom from some Laverda mechanics was to run without the breather ball installed. It's what I still do now.
 
Rob said:
Indeed..but where will it push it??

Chuck the breather ball away.
Or, if you're not made of brave stuff, remove it and see how the bike runs then. Back in the day, received wisdom from some Laverda mechanics was to run without the breather ball installed. It's what I still do now.
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Out of the engine seals and gaskets. Not past the rings or valve guides I should think.
Paul
 
I think you see it incorrectly Paul. The inside of the cylinders is in fact outside the pressurised volume of the engine oil containing casings.
 
BlackJota said:
It could suggest that the copper sealing gaskets between the head and header pipes is not doing it's job and is sucking oil through the exhaust valve guides. Check the gaskets are in place and header pipe clamps are tight. Happened to me years ago.

Another cause of oil in my pipes was when a workshop filled the oil to the dip stick level when it was screwed in at an angle and not hanging vertical as per the book, resulted in way too much oil in engine
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These are both really good suggestions. Given it started out ok and then started to burn the oil, that tallies with the copper exhaust gaskets softening with initial heat cycles and loosening a bit. Re-tightening the exhaust headers is a requirement after a couple of heat cycles after installation of new gaskets. Over-full oil is another good one although that usually just pukes out of the breather all over the rear tyre (great design). Failing that, Rob's suggestion of glazed bores also fits. Possibly ridden too gingerly during the initial period?
 
In case anyone is interested, I changed over the oil breather ball hoping for a cheap fix, no luck. Also tightened up the exhaust gaskets, again no luck.

Dropped off the bike with Ged at GCS, engine out and head+barrels off.

Double trouble:

1) Oil coming up behind the valve guides, which had been bodged when the head rebuilt with new guides and valves in 2016 by Moto Corsa

Head sent to Keith for resizing guide holes and new guides.

2) Oil coming up past incorrectly fitted oil ring (again by Moto Corsa) plus ring recesses worn and out of tolerance. So barrels off for rebore and new Omega pistons (supplied by Keith).

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Hopefully I will get the bike back this side of Christmas, thanks to Ged and Keith‘s expert diagnosis and skilled work.

Paul was right, “expensive” !

Will let you all now when II’m back on the road
 
Bloody hell. Someone (at Mota Corsa?) needs a kick in the arse for fitting the oil ring like that. I don't think it could have got messed up like that in service.

You should send them that photo. I doubt they'll acknowledge any fault, but it's valuable feedback for them if they want to improve their quality of work. They might take a bit more care with the next bloke they do work for.
 
Sadly, I've also experienced a similar standard of work from Moto Corsa. Never again! :mad:
Cost me a load of grief and a large chunk of money to have it done correctly.
 
I'm glad that the diagnosis is there. A right pain though.
I've never heard of Moto Corsa but there are very few people out there with an established reputation doing Laverda work. Unfortunately because in a few years, it'll likely be over.


Paul
 
I was reading through this posting set from #1 and got right to the penultimate post and thought to myself that

"this must be bodged fitting of valve guides (too tight tollerance) and they are probably binding on the stems and riding up and down with the valves" looks like I might have been correct, but the oil control ring beggars belief and would have made some funny noises and cause a bit of oil burning right from the word go as well. What are the visible marks that can be seen lower left on the piston wall in your shot? Moto Corsa is being blamed for the oil ring defect, but didnt you state that Ged had honed the bores and re-ringed the pistons?

"The engine has had major work over the last few thousand miles including new valves, followers and guides, pistons may have had some attention, new rings and honing ( not sure how good , suspect fairly basic)" was all this Moto Corsa? or some and some?

It (the head) is very likley in the right place now as are the barrels, hope it can be reclaimed.
CLEM
 
Oh man... that's really a pitty... Hope the bike comes back together soon and you can appreciated it again! Tough time to bed-in the engines though after a serious overhaul, have two engines which need to complete their first 1.000km... :rolleyes: hard to keep patience, especially on the 1000 SFC that runs best beyon 3.000 rpm...
 
CLEMTOG said:
I was reading through this posting set from #1 and got right to the penultimate post and thought to myself that

"this must be bodged fitting of valve guides (too tight tollerance) and they are probably binding on the stems and riding up and down with the valves" looks like I might have been correct, but the oil control ring beggars belief and would have made some funny noises and cause a bit of oil burning right from the word go as well. What are the visible marks that can be seen lower left on the piston wall in your shot? Moto Corsa is being blamed for the oil ring defect, but didnt you state that Ged had honed the bores and re-ringed the pistons?

"The engine has had major work over the last few thousand miles including new valves, followers and guides, pistons may have had some attention, new rings and honing ( not sure how good , suspect fairly basic)" was all this Moto Corsa? or some and some?

It (the head) is very likley in the right place now as are the barrels, hope it can be reclaimed.
CLEM
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Ged showed the piston to me when I was down at his place Clem, I very much doubt that he fitted it.
 
Thank you all

Just a couple of corrections:

Ged didn’t do any work to the pistons, he only serviced the bike at the beginning of the year. And buggered if I know what the marks on the pistons are, I’ll ask Ged when I see him.

I looked back over the old receipts that came with the bike. The head had extensive works by Moto Corsa in 2016 ( only 2000 miles since), detailed printed invoice. The barrels and pistons had work prior to that and I have hand written invoice. So apologies for my mistake, Moto Corsa didn’t work on the head, but I have ask why, during a major engine overhaul didn’t they make some simple investigations. Copy of the hand written invoice your amusement

D2990D86-8127-4454-8C10-071251149742.jpeg

Again thanks for you support
 
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