It started out so simply

[guzzi323]

A week ago I was tuning up my Scura and decided to replace my somewhat cracked intake boots with new ones. I pulled the injectors and was shining a flashlight down the intake ports and was pleasantly surprised that Guzzi did a decent job of cleaning them up at the factory.

Then I noticed the little puddles of oil sitting in the bottom of the manifold. The bike has 50K miles on it and though I think it shouldn't need new guides at that tender age it's not completely unreasonable.

I pulled the heads and took them to the machine shop last Monday. They think they'll have them disassembled this week and give me a call. Today I decided to tear back into the motor and start cleaning gasket surfaces and such and make a parts list for ordering. One cylinder came off and everything looked great. The other one came out and there was significant damage to one side of the piston and a good bit of scoring in the cylinder

 

As I examined the cylinder further I find on the opposite side from the scoring there is a large crack about two inches long. It's a little hard to see so I highlighted the area in photoshop. It goes completely through the cylinder wall.

 

I've never seen anything quite like this before. I did have a low speed incident 6 months ago where I dropped the bike at about 10 MPH and it fell on that side. It really only damaged the head guard and scuffed the ignition wire so I have a hard time believing that caused this cylinder damage.

 

I guess this is an 'opportunity' to put Mich Rich pistons in (once I find a cylinder) but this is ending up being a very expensive tuneup.

 

johnk

[dlaing]

Oouch.

That sux.

You could also take the opportunity to sink even more money into a Big Bore, water cooled kit.

[Tom M]

Yikes! That's horrible John!

 

Aren't you one of the unfortunate folks who had their oil filter unscrew itself? If so I wonder if the scoring could be from lack of oil? The cracked cylinder is just bizarre. I don't see how a drop could cause that (crack below the crankcase mounting surface), but I don't know what else would. Maybe Pete or Greg will weigh in here their with take on it. They must have seen something like this before.

[guzzi323]

Yikes! That's horrible John!

 

Aren't you one of the unfortunate folks who had their oil filter unscrew itself? If so I wonder if the scoring could be from lack of oil? The cracked cylinder is just bizarre. I don't see how a drop could cause that (crack below the crankcase mounting surface), but I don't know what else would. Maybe Pete or Greg will weigh in here with take on it. They must have seen something like this before.

 

Yes I'm one of the lucky folks who got to freshen up my bottom end a year or so ago.

I thought about the oil filter incident when looking at this current round of damage but the rob bearings were really minimally damaged at that time so I can't see how this would have been related to that.

 

If anybody's got a good left cylinder looking for a home it appears I'm shopping for one.

 

johnk

[Dan M]

Doesn't seem likely the drop would crack the cylinder, especially down low like that. I wonder if whatever got in there to score the piston and bore wedged momentarily and caused the crack. Surprising the piston is not cracked. Any telltale bits in the sump?

[guzzi323]

Doesn't seem likely the drop would crack the cylinder, especially down low like that. I wonder if whatever got in there to score the piston and bore wedged momentarily and caused the crack. Surprising the piston is not cracked. Any telltale bits in the sump?

I agree about the accident being an unlikely cause of this. It's just all I could think of.

I had the pan off at the beginning of all of this and there was no sign of problems. I also took a compression reading after adjusting the valves and it was 170-175. I don't know how accurate my gauge is but things were at least even.

[drewscura]

were your intake boots cracked badly enough to allow debris into the engine? or were they just cracking as in drying out and looking ugly?

[guzzi323]

were your intake boots cracked badly enough to allow debris into the engine? or were they just cracking as in drying out and looking ugly?

 

There was no visible cracking on the inside, even when flexing the boots. Though there may have been an air leak I'm sure it wasn't possible for anything beyond air to get through.

I'm doubtful I'll ever know for sure what happened.

 

johnk