Need a little bit of info (Breva 1100 top end)

[EvanM]

So I've got the top end off the bike, trying to figure out where my oil consumption problem is. Right now, I'm trying to figure out if my piston ring gap is too large. We measured it at .0200IN (0.51mm).
Should I replace my rings? The bore looks good.
Also, does anyone know where I can get better valve guides while I'm at it? Both my exhausts have a lot of play in them, and the intakes have some as well.
Thanks,
Evan

[Vasco DG]

Needs rings, needs guides or K-Lines for the guides.

Oil consumption is sometimes an issue with smallblocks of this era, nobody knows why.

Pete

[EvanM]

Hey Pete, its the 1100, the big block.
On that note though, how well do those k-lines work? thats all I could find any info on as far as the guides go.
Thanks,
Evan

[Vasco DG]

Sorry, I'm an idiot. At pub at the moment will reply later.

(burp.)

Pete

[Vasco DG]

K-lines work splendidly and have advantages over re-guiding. Firstly the scrolled nature of the liner means that they are actually better at retaining oil and therefore wear slower than the parent guide material. Also, because the bore of the lined guide remains concentric with the seat less material has to be removed from the seat when re-cutting the valves. Unless the guides are loose in the head it is far better to use K-lines than to re-guide as knocking guides in and out invariably causes wear to the casting, hence the need for oversize guides.

I've used them in Guzzis for decades, including race engines, and have never, not once, had any problems with them at all.

Pete

[EvanM]

Thanks for the info Pete, looks like I'll probably go this route.
Also, for the piston/rings. My pistons measure out to have some wear on them. Do you know if there is anyone who makes a better aftermarket piston for the 1100? Or should I just got stock piston/rings again?

Thanks again
Evan

[Vasco DG]

How many miles has this thing got on it? What sort of wear? Remember, pistons aren't round so don't be alarmed if they don't measure the same from every angle around, it shouldn't be more than a few thou any which way though. Really though Guzzi pistons should last a very, very long time. If wear is excessive and is coupled with accelerated ring wear I would suspect over fueling. It hasn't got an O2 sensor Fooler or a PC fitted has it?

Pete

[EvanM]

It has 62000km on it right now. My dad did the measuring, so I'm not too sure how he measured, but he said that there was some wear on the pistons. It has had a PC and custom map by Todd for the past year, though I am removing it for this upcoming year, however the oil consumption has always been an issue since I bought the bike.

[Vasco DG]

Well my guess is that it's been overfuelling, hence the ring and piston damage. I have a Stelvio in bits at the moment that was grossly overfuelling due to O2 sensor foolers being put in. After 4,000 km with them in the cam chains were shot and it had ring gaps of a hundred + thou!

Obviously I can't say for sure without seeing for myself but if it was mine I'd almost certainly stick a boron ball hone through the bores lightly to de-glaze them and just re-ring it and see how it goes. That and K-lines and new valves should freshen it up. Don't treat it to gently when running it in and don't run the oil above half way up the stick. It might be an idea to have a squizz at the camchain too.

Pete

[EvanM]

Thanks for the info Pete!
How would I go about looking at the chain?

[Vasco DG]

Bust open the timing chest. Is the motor still in the frame?

Pete

[EvanM]

Yes, it is in the frame

[56Pan]

Well my guess is that it's been overfuelling, hence the ring and piston damage. I have a Stelvio in bits at the moment that was grossly overfuelling due to O2 sensor foolers being put in. After 4,000 km with them in the cam chains were shot and it had ring gaps of a hundred + thou!

Obviously I can't say for sure without seeing for myself but if it was mine I'd almost certainly stick a boron ball hone through the bores lightly to de-glaze them and just re-ring it and see how it goes. That and K-lines and new valves should freshen it up. Don't treat it to gently when running it in and don't run the oil above half way up the stick. It might be an idea to have a squizz at the camchain too.

Pete

I can understand the accelerated wear due to the overfueling, but did that damage the cam chains and how, if so?  Can't figure that one out.

[Vasco DG]

Fuel in oil degrades lubricant, pins in chain wear, chain elongates further than tensioners can compensate for.

[56Pan]

Fuel in oil degrades lubricant, pins in chain wear, chain elongates further than tensioners can compensate for.

Okay.  Makes sense.  Just thought it was running bad rich, not to the point it was washing down the cylinder walls.  There's a modification I'm staying away from.