Valve seat failures

[callison]

I sent the heads of the Bugswatter off to Mike Rich a couple of months ago. I got a call yesterday that he'd finally unpacked them and did a preliminary check out.

 

My left exhaust valve seat was the worst he'd ever seen on a square fin. The guide was so loose the valve hammered the seat into the head. Small wonder the bike wouldn't idle or run below 3000 rpm. Mine is probably the highest mileage square fin he's seen, but he has seen damage nearly as bad in as little as 4000 miles on Guzzi engines.

 

The upshot of this is. The valve and guide materials MG uses are not optimum, maybe not even good. You can expect the soft valve stems to wear with the guides running loose as a result and seeing damage at some point in the life of your engine. There is probably no guideline as to how many miles is crucial, some riders, like Ken Hand, go hundreds of thousands of miles without problems, others get less than ten thousand and things go bad. A compression check on my engine did not reveal this problem, but it sure ran lousy and no amount of tinkering seemed to improve it.

[Guest John T]

Ditto here.

 

My heads hade a little more than 4000 miles and Mike Rich gave me the call to tell me that the valves were starting to wear on the stems. He first thought it was the guides cutting into the valves but has since discovered that the valves are soft.

 

Does Guzzi actually make these valves and stems in house or are they purchased from another vendor?

 

Well, I'm not worried, Mike put new hardened valves and guides in while he had them.

[al_roethlisberger]

Same here, as reported when Mike tore into my heads some months back:

 

2) Apparently MG has used relatively soft valves in our bikes, and had a rather sharp guide. Mike has noticed(and warned me ahead of time) that the OEM valves he's received have worn significantly over relatively minimal mileage. He's seen bikes with 5000 miles with .005 wear, and the guides worn similarly. This is caused by the lateral forces on the valve-stem from the rocker, the guide having a very sharp top edge, and the softness of the valves. He tested the valves and consistently find them to have a "Rockwell-c" hardness of 29.5-30, where in his opinion they should be at least 35.

 

My valves' stems were worn .002 with only about 3000 miles on the clock. While not a big deal yet, one can extrapolate that as this wear gets worse, it will only accelerate, and then the guide and even the boss that the guide fits into will wear out. Result?... oil burning, poor valve-train performance, binding, etc...

 

So, the moral of this story? Keep an eye on the wear of your valve stems and guides, and if you have a chance to change them to a better set, you may want to take that opportunity. Because Mike says every late model Guzzi he's worked on has this valve wear issue.

 

...so it's apparently a problem across the board. He installed the harder coated valves in my bike as well, so it should now be problem-free for the forseeable future

 

al

 

 

:1000

[callison]

My heads had 57,214 miles on them when I sent them off. That's just... a bit... more... than you guys . Mike said the exhaust valve had acted as a cutting tool and did a fine job of sinking the seat into the head. Providing the head isn't cracked, it can be salvaged. Otherwise, he'll find a core. These are going to be some very expensive heads by the time they're returned. Now I have to send him the rocker arms for inspection and/or re-grinding as well.

[al_roethlisberger]

.....cracked head!! I hope not...

[Murray]

Silly question but did you notice any signs ther was something amiss withthe stems/seats. Using oil, valve clearances all over the shop metal in the oil low compression? I have very similar Kms on my carbed 1100 sport (73 000) this kinda talk make's a person parniod. Recent compression and leak down test showed full compression and no leaks valve clearances are very stable ie I only do them every 10 000kms cause there is no piont doing them every five and usally I wonder why I bother. (run 0.2mm or 8thou for both if your're wondering). Havn't really got anything to make me think things are going wrong however would be intrested to know.

[jrt]

This is not good news. Perhaps I can use this as an excuse to send my heads to Mike Rich

 

Oh, well. I guess if caught early enough, then no damage done. I'll check mine out this winter.

 

Thanks for the heads-up, guys.

 

Cheers,

Jason

[callison]

I was (and remain) clueless as to how you check valve guide wear. I opted to leave heads on the entire time I had the bike and only torqued them occasionally while doing the valves on a regular schedule. The Bugswatter has always been a bitch to keep running smoothly. When she decided to not run below 3000 rpm at all, I knew there were additional problems. I tried a different tps sender, checked all of the sensors and re-wired for dual ECU's so I could try Cliff Jeffries My16M. Cliff's computer improved stuff somewhat, but there was something so fundamentally wrong with the engine, that it had to be mechanical and that means the top end. So, I pulled them apart and sent them off to Mike. I had a significant carbon trail from the left guide to the crankcase vents, so that would be one thing to look for prior to taking the heads off. Also, some of the washers and such were carboned into place and difficult to remove. As I posted earlier, Mike said mine were some of the worst he's ever seen. Unfortunately, it seems that all of the big block Guzzis have this problem. Mine was exacerbated by high mileage. I think I was #3 or 4 worldwide for high mileage on a spine frame when I tore it down.

[al_roethlisberger]

As I posted earlier, Mike said mine were some of the worst he's ever seen. Unfortunately, it seems that all of the big block Guzzis have this problem. Mine was exacerbated by high mileage. I think I was #3 or 4 worldwide for high mileage on a spine frame when I tore it down.

 

 

...unfortunately this doesn't "make the case" for the much vaunted MG longevity and durability claim! Ah hem...

[Murray]

. I think I was #3 or 4 worldwide for high mileage on a spine frame when I tore it down.

Pfffttt what? there is at least two 1100 sports with more kms than mine locally. One has 90 000 the other has 120 plus. In in 1999 I sold a silver 1100 sport with 60 000km's I would of thought that someone who was serious about touring would of racked up more than the bunch of weekend warriors that genrally ride guzzis here.

[jrt]

I'm curious as to what you or Mike mean by 'big blocks'. Just spine framed sports or all the tonti frames as well?

 

Jason

[callison]

Pfffttt what? there is at least two 1100 sports with more kms than mine locally. One has 90 000 the other has 120 plus. In in 1999 I sold a silver 1100 sport with 60 000km's I would of thought that someone who was serious about touring would of racked up more than the bunch of weekend warriors that genrally ride guzzis here.

 

Well Murray, like I said. "I think", based on the best information I've been able to dredge up off of the net, which isn't a lot. 90,000km is a tad less than the 57,214 miles on mine and 120,000km is a bunch more. There are at least 2 or 3 other Sports in the USA that have more miles than mine, so I popped a number as a guess. Mea Culpa. The bike is still definitely a high mileage spine frame. The 1100 Sports have been around years longer than the FI models, they should have a higher population of high mileage bikes. I bought my Sport 1100i new just 5 years ago this month. In that five years, I didn't ride it for 11 months after carpal tunnel surgeries and only put 3000 miles on it the last 14 months because it ran so badly. It gets used, it's my favorite bike. I bought the V11 Sport last June. I'll have 20,000 miles on it this month as well. I put 20,000 miles on the California in the last 18 months too. Now consider the issue of the original post. ALL of the big block engines (Californias, Stones, EV's, Bassa's - what have you) have a likely potential for valve seat damage due to poor materials. And I'm racking up miles (or is that wracking...?) on three big blocks. That poor valve material is going to cost me three times. And I don't have a car to fall back upon. I better get the Bugswatter back together soon as one of the others may be next.

[mikie]

I'm not very mechanically minded (I should begin all of my posts with that line); however, I was looking at an interesting set of berings and washers developed - so he said - by Matt Capri at South Bay Motorsports last week when my bike was there for some warranty work. He said that these go inside each rocker arm on the Guzzi, so there are four sets per bike (bering sandwiched between two washers), and that they tighten up the clearance so the valves don't bang so hard against the rocker arms. He also claims that these quiet the valve noise down significantly and prolong the valve life while making the adjustment requirements much less frequent. Might this be a solution for the above-mentioned problem, and has anyone on list had experience with this and endorse this modification? Total cost is $120 for parts plus one hour labor.

[jrt]

Like these? (Taken from MGCycle website). They're cool looking!

$120 doesn't sound like too much for a Guzzi part (sigh). Anyone else tried these?

 

They might help for rocker guide wear, but it wouldn't help valve stem wear. The valve is moving up and down in the guide- the stem of valve is what's wearing out, so then the valve can wobble around while it moves up and down. That, in turn, wears out the seat that the valve sits in (in the combustion chamber).

[RichMaund]

Roller tipped rockers and proper shims instead of spings! Very cool!

Theoretically at least, this set up offers many advantages.

I wish I could spare the funds for it right now.