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Stelvio valve clearance check at 3400km: Facts!

luc

Just got it firing!
Joined
Nov 10, 2008
Messages
14
Hi gang,
Hereby some facts and figures on valve clearance. Following Pete's suggestion that the 4V heads need to be carefully checked during the first 10000km , I decided this afternoon to check it out on my 3400km old Stelvio.
Background:
When new, I am convinced my dealer checked the valves.
The first service was taken at around 1700km, I will check later with my dealer if he checked the valves
As a Guzzi driver with 25yr experience, I have driven the bike carefully so far

Current situation after 3400km:

Left cylinder inlet valves clearance:
Between 0,06 and 0,07 mm
Left cylinder exhaust valves clearance:
Between 0,08 and 0,09 mm

Right cylinder inlet valves clearance:
Between 0,05 and 0,06 mm
Left cylinder exhaust valves clearance:
Between 0,07 and 0,08 mm

Conclusion:
The valve clearance has tightened significantly in relative few kms. The clearence is uncomfortably tight to my view, if I had added an other 6000km before the next service ....

Thanks for the advice Pete! I can recommend all other 8V owners to get their spanners out too B)

Luc
 
Thanks for posting this Luc, very interesting information.
With a hot engine your valve clearence would probably be zero or even a slight opening of your valves (when they are supposed to be closed).

While I agree with Pete Roper this would result in extra strain on the valve mechanism it should result in loss of power and/or burnt exaust valves, not in destruction of the mechanism.

Anyway I never got past 700km (437 miles) so I think at least in my case this can be ruled out as a couse of failure.
 
klaas123 wrote:
this would result in extra strain on the valve mechanism it should result in loss of power and/or burnt exaust valves, not in destruction of the mechanism.
For sure tight valves won't on their own lead to destruction unless they get so tight that the valve hits the piston, but the real question is why have they changed so much and so rapidly, and is that change an indicator of something, or normal for this particular design.

A difficult question to answer me thinks, and one which in the end only MG can answer.


Great post Luc!
 
Mike.C wrote:
klaas123 wrote:
For sure tight valves won't on their own lead to destruction unless they get so tight that the valve hits the piston, but the real question is why have they changed so much and so rapidly, and is that change an indicator of something, or normal for this particular design.

Sure Mike, valves hitting the pistons would give nasty results however I think there is (should be) a margin more than a couple of tenths of millimeters before this can happen.
 
No, Klaas is right there, what would cause valve damage is the valve timing changing or the valves seizing open, that isn't happening.

Conventional wisdom is that the valves will be the first part to be damaged if the clearance closes up as the valve is held off its seat and the burning gasses which are as hot as an oxy flame if the AFR is right zoom out past the valve and burn off the margin.

Problem is that if the clearance just closes up to nothing or the valve is not held off its seat for this to happen the secondary effect is that the tappet rides the cam, there is no point in its rotation where oil can actually get between the tappet and the face of the cam, therefore it can't wedge and wear will occur.

I AM NOT SAYING THAT THIS IS THE PROBLEM, SIMPLY THAT IT IS A POSSIBILITY AND GIVEN THE WEAR THAT IS OCCURING IT IS A POSSIBLE EXPLANATION.

Pete
 
Also, the reduction of valve clearence can only be explained by the valves "settling" in their seats I think.
This could never result in the valves getting any nearer to the pistons than inittialy set at the factory.

(This is a reply nto Mike so should be read before Peter's reply above)
 
pete roper wrote:

I AM NOT SAYING THAT THIS IS THE PROBLEM, SIMPLY THAT IT IS A POSSIBILITY AND GIVEN THE WEAR THAT IS OCCURING IT IS A POSSIBLE EXPLANATION.[/quote]

It sure is a possible explanation Pete but with the small amount of miles/kilometers I did with the bike keeping it below 5000 rpm I don't believe it can be the sole reason for failure.
 
Mine were set very wide ex-factory, wide enough for me to have concerns that they might be by-passing the rampings, so I closed 'em up. During the first few 1000kms the closed up very quickly, rapidly at first and then it slowly diminished until it stabilized at about 4,500-5,000RPM-ish. Just for shit and giggles I might do 'em again this week and see if they are still closing up, I'm up to 12,000+Km now.

Pete
 
klaas123 wrote:
It sure is a possible explanation Pete but with the small amount of miles/kilometers I did with the bike keeping it below 5000 rpm I don't believe it can be the sole reason for failure.

I set mine to 4 and 6 thou before I rode the bike, by 800Km they had closed up to the point where there was no detectable movement and I couldn't get a guage in between the valve and the lash cap.

Pete
 
After more than a year of 8V production, known problems with them and inclination of valve clearence I would think the factory will set a "fail safe" clearence if that is the problem. My bike wasn't a left over at the dealer, it was ordered at the importer for me.
 
klaas123 wrote:
After more than a year of 8V production, known problems with them and inclination of valve clearence I would think the factory will set a "fail safe" clearence if that is the problem. My bike wasn't a left over at the dealer, it was ordered at the importer for me.

Yes, but this brings us around again to the fact that if the clearances are too large then the tappet will by-pass the rampings and then you risk cam damage by flogging the opening flanks. Is this likely to be a problem? I DON'T KNOW but it is something I considered and thought that a better option was regularly checking the valve clearances until they seemed to stop moving.

Look, if we are going to look at the situation dispassionately we now have my observations of valve clearance dimunition in the early stage of use, this has been backed up by another poster who performed a similar check and found that his machine too was closing its gaps up more quickly than he would like. I think we can now say that this is one sure fire indicator that there is a TENDENCY for the gaps to close, it may not happen on all engines but on some it does. Is this relevant to the cam failures? WE DON'T KNOW. But the more we DO know the more it allows us to rule out as a root cause.

I STRONGLY advise anyone with a Nuovo Hi Cam to check their valve clearances lots and lots at least until they cease moving. this may not cure the problem but it certainly won't harm anything and will take 1/2 an hour or so of your life. So try living dangerously and take some preventative action or at least be willing to contribute to the pool of knowledge rather than relying on rumour, inuendo and hearsay and promoting them as fact.

As I said elsewhere, I'll check my clearances again this week and report what I find but the fact that so far my bike hasn't gone tits up and others have points, at least to my mind, towards my original suggestion not being without merit.

Pete
 
pete roper wrote:
Mine were set very wide ex-factory, wide enough for me to have concerns that they might be by-passing the rampings, so I closed 'em up. During the first few 1000kms the closed up very quickly, rapidly at first and then it slowly diminished until it stabilized at about 4,500-5,000RPM-ish. Just for shit and giggles I might do 'em again this week and see if they are still closing up, I'm up to 12,000+Km now.

Pete

You must be very quick with the feeler guages ;-)
 
Geordie wrote:
pete roper wrote:
Mine were set very wide ex-factory, wide enough for me to have concerns that they might be by-passing the rampings, so I closed 'em up. During the first few 1000kms the closed up very quickly, rapidly at first and then it slowly diminished until it stabilized at about 4,500-5,000RPM-ish. Just for shit and giggles I might do 'em again this week and see if they are still closing up, I'm up to 12,000+Km now.

Pete

You must be very quick with the feeler guages ;-)

Quick as lightning shit 'ed:laugh: :laugh: :laugh:

Well. I won't bother editing, too much fun:lol: :lol: :lol:

Pete
 
klaas123 wrote:
After more than a year of 8V production, known problems with them and inclination of valve clearence I would think the factory will set a "fail safe" clearence if that is the problem. My bike wasn't a left over at the dealer, it was ordered at the importer for me.

Hi Klaas, sorry to hear you have the record of blowing up an 8V engine.:( :( Do you happen to know if your dealer has effectively checked the valve settings before delivery? I am not very impressed by the Benelux importer, the test bikes I drove earlier in the year did not at all drive smoothly, giving me the impression they came right out of the crate...
I know my dealer is of the 'Pete Roper' -type: he is of the view that Mandello delivers a 'kit' that needs to be re-assembled before being road ready. On my Stelvio, he showed me a 1 cm piece of paint flake he found between a gasket of the final drive assembly.

Success with your bike!
Luc
 
1cm paint flake ???????????
10 mm , or 3/8" does anyone know what they're taliking about on this site ?

(quote pete roper) Yes, but this brings us around again to the fact that if the clearances are too large then the tappet will by-pass the rampings and then you risk cam damage by flogging the opening flanks. Is this likely to be a problem?

Metal expands with heat. It will expand the exact same amount every time, for the same given temperature.
 
Gary wrote:
?

(quote pete roper) Yes, but this brings us around again to the fact that if the clearances are too large then the tappet will by-pass the rampings and then you risk cam damage by flogging the opening flanks. Is this likely to be a problem?

Metal expands with heat. It will expand the exact same amount every time, for the same given temperature.

Which has absolutely no relevance to the issue of the tappet by-passing the rampings if the tappet gap is too large. So who exactly is it who doesn't understand?????:laugh:

Pete
 
:angry: OK stelletje nokkenasschijters en stoterstangzuigers:angry:
Wat ik bedoelde was dat er verf zat tussen het cardan huis en de eindoverbrenging en dat die er niet moet zitten. Dit ter illustratie dat men in de fabriek niet kan omgaan met precisie machines. Als jullie denken dat de hele wereld Engels praat en als jullie geen respect hebben voor mensen die het moelijk hebben om engelse technische termen te vertalen zijn jullie een stelletje loozers!

For the English: (plse google translate the above from Dutch)
Thanks for showing no respect that I am not native English and mis translated gasket. I said there was paint between the 'precision machined components' from the carc where it should not be. Just to illustrate that the factory is not set up to work with high precision machines.
Poor Forum if it is about a sport to have a laugh at people with good intentions:(
Luc
 
luc wrote:
:angry: OK stelletje nokkenasschijters en stoterstangzuigers:angry:
Wat ik bedoelde was dat er verf zat tussen het cardan huis en de eindoverbrenging en dat die er niet moet zitten. Dit ter illustratie dat men in de fabriek niet kan omgaan met precisie machines. Als jullie denken dat de hele wereld Engels praat en als jullie geen respect hebben voor mensen die het moelijk hebben om engelse technische termen te vertalen zijn jullie een stelletje loozers!
Luc
;) Funny shit! deze vertaling door Google is een optie die ik heb nooit geprobeerd. Het leven is te kort om misverstanden in de weg van de beurs. Hoop je te zien op de weg op een dag. Iedereen begrijpt een goede rit en een koude drank ;)


If this does not translate my meaning... I apologize in advance:unsure:
 
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