valve hardness is this an issue

[dlaing]

So is that step in John T.'s valve picture the difference in wear?

I am at about 21000 miles now. Assuming I have 6 times the wear, it must be time to get the bike to a nunnery, before she gets f.....

[al_roethlisberger]

The answer[Q: Can the dual-plug coil run on one plug?] would have to be no. When the magnetic field collapses, it induces a very high voltage across the secondary. The secondary's load is the spark plug. With no plug - hence no load - the secondary voltage will probably rise high enough to puncture the winding insulation and ruin the coil. Even hooking up a spark plug out in the air on the second lead would be preferable to operating it without any load.

 

Obviously you seem to know a good deal more about these things(electronics, coils, etc ) than I do, so humor me if I yet find that a bit incredulous that a modern coil would be designed that such an easily reproduced... even accidental... misconfiguration could ruin the whole coil

 

You may indeed be correct, but I still find it surprising, as I can see many cases such as an accident where the wire gets disconnected, or a plug is broken off, where it would not just be fail-safe to not ruin the coil in this mode, but would be very advantageous as limp-home mode to still run on at least one plug

 

hrmm, maybe though...

 

al

[Lex]

Al,

 

I can't say I've seen it personally but from what I understand Carl is correct. There is a huge amount of energy, if it is not sent off to the plug the very small gauge wire or its insulation fails.

 

Scary huh?

 

Lex

[Guest Jeff Kelland]

I mean no disrespect to anybody, and quite frankly I don't have the valve in my hand or the guide. However, I have looked at literally thousands of 4 stroke engine valves in my career. The photo in Al's post does not in my opinion show the wear pattern typical to engine valves. As the rocker arm pushes the valve open, it slides across the stem tip creating side loading.Typical wear will occur at the inside top and outside bottom. The stem, which in my experience will wear far faster than the harder valve stem, will wear in an oval fashion, the most wear obviously occuring at the matching points with the stem. This photo, and it's very limited view, shows something entirely different in my opinion. Some valves are necked down, which direction in the photo is the head? Also, some valves are made in two pieces, those pieces spun welded under pressure. This looks quite like those 2 piece valves I have seen. Also, the statement that the boss the guide is mounted in will wear, while possible I suppose, is usually the result of catastrophic failure. The wear would have to occur through the entire thickness of the stem wall. Most riders will realize that something is wrong long before this will occur, most likely in the form of noise and smoke and then if that were ignored, the valve dropping into the cylinder. I would really like to see more photos before making a diagnosis, but that photo to me is inconclusive and possibly misleading.

[al_roethlisberger]

Hi Jeff,

 

I'm no ASE mechanic or machinist, so I can only recount what Mike Rich described to me... which BTW echos your description of side-loading and appropriate wear on the guide and stem in specific areas versus even wear around the stem.

 

The photo above was not posted by me(it's John's valve), so I can't comment on the photo for sure... perhaps he can... but he may have taken the photo from an angle to accentuate the damage so that we could all see it clearly ...versus it repesenting concentric wear?? I dunno, but again maybe John can comment.

 

Bottom line though, when this and similar topics have come up for discussion, I simply defer to suggesting one call Mike Rich. He's more than happy to chat about these things to help one understand his observations. I'm sure he can describe it better than I

 

Feel free

 

Mike Rich Motorsports

21 Jerusalem Hollow Road

Manorville, New York 11949

(631) 874-7032

 

al

[Guest John T]

Here is another shot showing the top of the valve.

All of my valves showed similar wear. This one is .004 thou. worn.

The lower part of the valves look fine.

 

I was one of the first for Mikes headwork. He called and showed some concern for the amount of wear on a motor with so few miles. 3000 miles +/-.

 

He first thought it was the sharp edges on the top of the valve guide cutting into the valve stem. His guides are chamfered as to not cut into the valves.

He later started doing hardness tests and found soft valve stem.

 

I think it was Carls valves that were so worn they started to "rock" in the guide causing his valve seats to get all beat up. Also poor low speed running.

 

Maybe it was certain batches of valves that are soft. Ken Hand, Todd E and others have high mileage bikes that show no outward signs of this problem.

[Guest Jeff Kelland]

This is a much better photo, I will say that in my experience this is not how valves wear, however, because I can now see the location of the mark and the wear, I would agree that this valve is severely worn. I wonder if the problem is an overly tight clearance on assembly. I will call Mike Rich and ask his opinion. I'm never too old to learn something new! Sorry Al and John, I was reading this quickly at work and confused the posts, BTW, I have been ASE certified for about 15 years.

[Guest northend]

I wonder how come Mike Rich doesnt come on this website and give us ALL

the low down on this cylinder head stuff.

 

You would think that he could get alot of buisness off this website

[callison]

Maybe it was certain batches of valves that are soft. Ken Hand, Todd E and others have high mileage bikes that show no outward signs of this problem.

 

These guys don't have big valve Guzzi's. The milder engines have harder valves. The stronger engines have softer valves. Go figure.

[callison]

I wonder how come Mike Rich doesnt come on this website and give us ALL

the low down on this cylinder head stuff.

 

I don't think Mike's lacking for work, but is lacking for time. 99% of whatever he's told us has been posted here anyway. Basically, it comes down to whether you want to believe what he's passed on to those that have conversed with him. I'm just dreading the inevitable valve job on my V11 Sport because I'm up in the higher mileage regions already. 29,000 isn't a gigantic number, but as Al's bike showed, the damage can occur at quite low mileages and I'm well past those.

[docc]

So, short of disassembling the heads, what can we watch for?

 

Were you guys having to reset the lash more than usual/ ( Usual is probably no change at all or maybe 0.001" every 6000 - 12,000 miles.). Was there increasing valve train noise, smoking on start-up or decelleration? Plug fouling or increased oil consumption?

[al_roethlisberger]

Hard to say for certain in my case, as I didn't know anything about it until Mike was already taking my heads apart for porting

 

...and of course Carl's case was extreme

 

I suppose one might be able to tell something with some inspection during adjusting the valves, and of course the classic valve issue indicators of poor compression, oil, etc... would be symptoms.

 

Perhaps some of our certified mechanics can offer something more objective and specific though?

 

al

[docc]

Perhaps some of our certified mechanics can offer something more objective and specific though?

 

Yes, please!

[Guest Jeff Kelland]

It is relatively difficult to detect this condition without disassembly. Because the angle machined into the seat matches the angle of the valve, the valves tend to self center on closing. Therefore, loss of compression is not a good indicator of stem wear. It is possible to try "wiggling" the stems when you do a valve adjustment but this will only check for stem wear at the closed position. Some indicators might be seen by removing the intake and exhaust plumbing and inspecting the portion of the stem visible in the port. Look for excessive carbon buildup on the stem and back of the valve face, don't panic, some is normal! It is sometimes possible that exhaust will flow up the exhaust valve stem causing carbon buildup under the spring. Blue smoke after sitting, or idleing and then acclerating would also be an indication. Noise would only be likely after the problem was severe as the clearances are so small. Most of the valves I look at are from heavy duty diesel engines with high mileages, sometimes approaching a million miles. I have seen my share of auto and cycle valves as well. The wear pattern shown here is new to me (at least as it appears in the photo). I will look at mine when it's apart for the new cases, it is really the only way to know exactly the extent of the wear. Valve stem wear is generally very slow in progressing, maybe not so slow here in some cases. While .005 or so sounds like a lot, it is still a very small measurement, catastrophic damage is not real likely to occur here. Our experience over time will give us a better understanding. I would suggest that any of us that have our heads off for any reason remove and check the stems. That way we can build a data base and see what we've got.

[JuhaV]

Here  is another shot showing the top of the valve.

All of my valves showed similar wear. This one is .004 thou. worn.

The lower part of the valves look fine.

 

I was one of the first for Mikes headwork. He called and showed some concern for the amount of wear on a motor with so few miles. 3000 miles +/-.

 

He first thought it was the sharp edges on the top of the valve guide cutting into the valve stem. His guides are chamfered as to not cut into the valves.

He later started doing hardness tests and found soft valve stem.

 

I think it was Carls valves that were so worn they started to "rock" in the guide causing his valve seats to get all beat up. Also poor low speed running.

 

Maybe it was certain batches of valves that are soft. Ken Hand, Todd E and others have high mileage bikes that show no outward signs of this problem.

12929[/snapback]

 

Hi,

 

I just removed the heads from my Sport 1100i -98 with 33000 kms on the clock.

 

The valve guides and stems are so to say "gone". The valve stems look exactly like that shown in the pic posted by John T. I would estimate that there is about 0.08 - 0.10 mm clearance between the stems and guides which is clearly too much.

 

I believe that V11 and Sport have both the same type of valves : inlet 46.5 mm and exhaust 39.5 mm. This seems to be also confirmed by Guzziology.

 

Now, it seems that the material both of the guides and valves is way too soft. There seems not to be too much sense to put in new original parts if there is reason to believe that Guzzi has not done anything to fix this problem ?

 

Do you know any other source than Mike Rich for new valves and guides made of better material than the original ones ? Don't want to say that he is not a good source, because I think that he might actually be the best one, but I would still want to know what are the possible options here.

 

By the way, the bike did not smoke or consume oil or express in any other way that the situation with the valves was that poor. That is quite interesting !

 

br, JuhaV