What did you do to your V11 today?

[docc]

On 5/22/2023 at 1:54 AM, Martijn851 said:

Don't know, it's also 10/15 in the how-to on this site, followed by the 'like favorite oil' comment 

Ah, yes, @Martijn851, my 2000 Sport Owner's Manual also shows 0.10/0.15.

The "Decent Tune-up" thread uses 0.15/0.20. I wish I could provide the references for that derivation. Seems there have been some expert opinions and experienced outcomes on the looser valve lash . . .

 

[audiomick]

1 hour ago, docc said:

...Seems there have been some expert opinions and experienced outcomes on the looser valve lash . . .

I found a post in the german forum on the subject. Here is (slightly edited) what DeepL made of it:

Quote

The old cam has such long ramps that, with operating valve clearance of 20 to 25 hundredths, an opening angle of over 400° results.

With all the associated consequences: The valve is only seated in the seat for a very short time, where it can dissipate heat. Over a long period of time, it is only open by approx. 1-2/10 mm in the area of the ramp. This means that hot exhaust gases can additionally heat up the valve and seat.

Increased valve clearance can significantly reduce this effect. Because the ramp is very flat, one tenth more clearance equals 20 or 30° less opening angle. ... In addition, short control angles extend the period during which the engine can effectively compress or work off the combustion pressure.

In practice, I see it like this: The valve should start to open in an area where the ramp is still flat. Then it should immediately change to the steeper rising range, so that the valve is opened quickly. By the way, fast opening also improves filling, because the fresh gas column waits in front of the inlet valve to be allowed in.

With slow opening as with the original old cam, the pressure of the gas column in the inlet is already reduced by the 1-2/10 gap, without a flow coming into operation.

Racing cams have for this reason often almost no ramps. The increased wear is in this case not important, or is accepted.

Translated with www.DeepL.com/Translator (free version)

The translation is a bit rough, but one can get the gist of it I think. The "old cam" is the one that was used for many years in the big block Guzzis. I don't know if the V11 still used it, but the basic principles of the text still apply.

The text is a quote in a post from someone else than me, i.e. third hand or so. Nevertheless, I know who was being quoted. As far as I know, he studied motor engineering, so he probably knows what he is talking about.

[Tomchri]

16 minutes ago, audiomick said:

Getting back to what I wrote here:

 

I had another look today with my endoscope camera (bought cheap on a whim in an Aldi supermarket, it is amazing how often I use the thing...) through the hole for checking the timing marks on the flywheel. It looks a lot like there is oil in there. I reckon the gearbox needs to come off to have a closer look at things.

I'm trying to see the good side of that: it means I will also be able to have a good look at the bottom end of the shock, grease the shaft drive uni joints, lots of good things. It really is a bit of luck that I have to get in there.

At least that is what I keep telling myself...

I might have missed something here, but the the breather house, a clean bill of health ? I use the Shin Etsu when putting a new one on, and easy to fit on.  Rubbish rubber, time will tell. 

Cheers Tom.

[docc]

49 minutes ago, audiomick said:

Getting back to what I wrote here:

 

I had another look today with my endoscope camera (bought cheap on a whim in an Aldi supermarket, it is amazing how often I use the thing...) through the hole for checking the timing marks on the flywheel. It looks a lot like there is oil in there. I reckon the gearbox needs to come off to have a closer look at things.

I'm trying to see the good side of that: it means I will also be able to have a good look at the bottom end of the shock, grease the shaft drive uni joints, lots of good things. It really is a bit of luck that I have to get in there.

At least that is what I keep telling myself...

After five years of chasing oil leaks, I found many contributors, but finally had to address the eight (8) leak sources in the clutch area. So nice to have these all buttoned up!

 

 

[audiomick]

30 minutes ago, Tomchri said:

...the breather house, a clean bill of health ? ...

Thanks, Tom. I didn't know that the breather system might be a potential culprit here. I'll have a closer look at that.

Also @docc thanks for the link to that thread on the subject.

[docc]

3 minutes ago, audiomick said:

Thanks, Tom. I didn't know that the breather system might be a potential culprit here. I'll have a closer look at that.

Also @docc thanks for the link to that thread on the subject.

Hey, best case, and very likely, scenario is the rear breather hose connection is leaking through there. Worth checking this first!

[audiomick]

1 minute ago, docc said:

 Worth checking this first!

Yes, that has just jumped to the top of the list. Thanks again.

[Martijn851]

9 hours ago, docc said:

Ah, yes, @Martijn851, my 2000 Sport Owner's Manual also shows 0.10/0.15.

The "Decent Tune-up" thread uses 0.15/0.20.

I'll try that next time. For now the engine runs way smoother than before, so that's a win.

[audiomick]

11 hours ago, audiomick said:

I found a post in the german forum on the subject (of more valve clearance).

It occurred to me that I should perhaps expand a little on the quoted post. The text came in conjunction with some diagrammes of measurements of a cam that the quoted person had made himself. The text should not be understood as a recommendation to always set more clearance than the manufacturer specifies. The recommendation for greater clearance on the old guzzis is based on measurements and empirical trials on that particular motor.

It seems that the manufacturer struck a compromise very much in favour of low wear and tear on the valve train and quiet running (i.e. very long ramps on the cam to save stress on the pushrods and rockers...). The recommendation for more valve clearance shifts the compromise towards a bit more valve train noise, less thermic stress for the valve seats, somewhat better performance (at least theoretically), and perhaps a little more stress for the valve train.

[docc]

[moderator edit]:

While the valve adjustment and breather hose/oil leak conversations are still intermingled here, I moved the TPS discussion to a more dedicated place:

 

[audiomick]

22 hours ago, docc said:

...the rear breather hose connection...

I was in my garage briefly today, and had a look. I saw a hose, about half an inch thick, that goes in to the crankcase vertically just in front of the end of the crankcase before the clutch bell housing starts. Very, very oily. I think we're on the right track.

[Tomchri]

And it coud be at the front going into the spine. leaving oil all over.

Cheers Tom.

[audiomick]

Thanks, Tom.

I'm planning to take the tank off again in the next week or so. I'll have a good look then.

[footgoose]

4 minutes ago, audiomick said:

Thanks, Tom.

I'm planning to take the tank off again in the next week or so. I'll have a good look then.

I've had 4 6speed V11. A 2000, 2X 2002, and an 03. All had crank vent tubes in various stages of disintegration. They aren't made to handle the heat and oil mix. At least the oem's weren't.

Leaks often presented dripping onto the center of the crossover.

this one.

https://www.mgcycle.com/index.php?main_page=product_info&cPath=71&products_id=1186

[audiomick]

Ok, got it. This one:

https://www.stein-dinse.com/de/search.html?grp=&searchStr=30157400

 

As a matter of interest, would it be feasible to replace that with a piece of plain tubing, or are the pre-formed bends in the hose "absolutely necessary"?