Leak down check.

[Stevex]

Taking the LM2 over to a friends in about an hour to do a leak down check.
Will be interesting to see the condition of the heads...36 years old, 36,000 miles and
no air filters ever fitted (to my knowledge).

[normzone]

That will be interesting - raw air diet, low miles, many years - have the head gaskets ever been changed ?

[Stevex]

Heads and barrels came off a year ago during the refurb I carried out. At the time, the heads weren't touched.
I'm confident the heads and barrels haven't been stripped since new, so all original.
So...36K miles with no air filtration, got to say I was fully expecting to have to remove the heads and have a full recondition carried out. However the RH leak down came in at 10% leakage and the LH at 15%, which I'm very happy with, all things considered.
Won't be taking the heads off this winter and now I've got a datum to work with for another check this time next year.
During the test, on both sides I removed the rocker covers, and could only hear and feel air escaping via the push rod tunnels, indicating the leaks were coming from the rings / bores.
The engine was run for about 5 minutes with about a half mile journey to my friend's place, prior to testing.

[rodekyll]

IMO 15% is excessive.  10% is marginally acceptable.

[MGPilot]

IMO 15% is excessive.  10% is marginally acceptable.

Is there any factory guidance on leak down numbers? 

I've seen figures for aircraft engines, a few industrial, but haven't seen any for most consumer goods. On my aircraft engines, 15% would have been just fine...better than many. We were a lot more concerned with cross-cylinder differences than a shared, equal net value.  Mainly just tracked the net changes over time to make sure there weren't sudden changes.

[rodekyll]

Back when I did dealership work (70s and 80s), Datsun factory said 9% max, iirc.  VW watercooled was 10% max.  Toyota was 8% max.  There was Kentucky windage allowed based on where the leaks were.  For example, all 9% of Datsun's leak at the rings was more significant than 3% rings, 3% intake valves and 3% exhaust.  Miles are also factored in.  I don't recall any specs for +10% overall.  Modern materials and tolerances may have changed things . . .

Leakdown values can change dramatically after a few miles on a fresh maintenance service.

[Stevex]

IMO 15% is excessive.  10% is marginally acceptable.

Is this backed up with any Guzzi specific evidence?
I trawled the web for info on leak down checks and although I couldn't find anything relative to the Guzzi,
10-15% was generally accepted as good, with any reading over 20% needing to be investigated.
I'd be interested if anyone else out there has done this check on their V twin, what readings you got and what, if anything, you did about it.
Personally from what I've read, I'm happy with the results for now, I don't think the leakage I've got requires rectification at the moment. Would be interesting to compare other's results though.

[rodekyll]

No, I have no guzzi-specific data to back that up.  I was generalizing from those other engines.

[redrider]

I purchased a tester and checked the 89 Mille GT and V11. The Mille has over 150k miles with K&N pods and a port job done by me 10 years ago. Sinestro-1-2%. Destro-1-2%. The V11 with 60K does the same. Lop off 10% of your torque and HP. Not wanting to be a Richard but every engine I have rebuilt at the dealerships had mostly valve leaks at 10%. Guzzi heads are really easy to freshen up and the porting does wonders for smoothness. My Mille valve seat alignment was awful.

[PeteS]

I agree 10-15% is excessive. All my rebuilds are around 1% when new and if they get above 3% I schedule the heads to come off. I use Total Seal rings so any leakage is valve related. Get those numbers down and you will notice a significant increase in low end grunt.

Pete

[Chuck in Indiana]

On an aircraft engine, leakage by itself isn't cause to tear down the engine.
Except.
10% difference between them. That said, 80/70 (a little over 10% leakage) is where mechanics begin to give it a serious look. There *are* special cases where a *lot* of leakage is said to be ok, though. Continental O-470 for instance.
On a Guzzi, I'd be fixing anything over 10%.

[jacksonracingcomau]

During the test, on both sides I removed the rocker covers, and could only hear and feel air escaping via the push rod tunnels, indicating the leaks were coming from the rings / bores.

But not always true
Head gasket blowing into pushrod tunnel will show exactly this.
Obviously, I can't tell from here, quick test would be check torque on head nuts but I'd  go in anyway, 15% is a lot to lose.

[Stevex]

But not always true
Head gasket blowing into pushrod tunnel will show exactly this.
Obviously, I can't tell from here, quick test would be check torque on head nuts but I'd  go in anyway, 15% is a lot to lose.

Yep, I'm coming to that conclusion myself after the replies here...oh well 

[Chuck in Indiana]

Ok, here's 80/65 on my home made leak down tester:

Here's what that looked like..

[oldbike54]

Ok, here's 80/65 on my home made leak down tester:

Here's what that looked like..

 Oh heck Chuckie , a bit of honing will suffice there  Good grief , that lump was still running ?

  Dusty

[Stevex]

Here's what that looked like..

It dropped a valve at some point then Charlie?

[Chuck in Indiana]

Yeah, it had dropped a valve and the Distinguished Previous Owner just honed it, put er back together, and sold it.  I'm guessing that he'd had all the Lario fun he could stand.  When I tore it down, I saw signs of at least two valve drops.

It was running fine. I've seen much worse that was running ok over the years.