Plse Help ID O ring for Lafranconi exhaust balance pipe Lemans CX100 w updates

[80CX100]

      Gutsibits description    "Fits Moto Guzzi Le Mans 1, Le Mans 2 useful Moto Guzzi model information| Lafranconi Silencer O Ring EXA14997"

     As I plod my way through my bike doing the high handlebar and suspension work, I'm discovering a few little gremlins along the way,lol.

     When I pull the Lafranconis and balance pipe off,,, there is absolutely no sign of the 2 big O rings, meant to seal/mount the balance pipe to the flanges in the mufflers.

      I'm baffled (groan),lol,,,, the pipes have only been on a few years,,, with very little use,,, I don't know if they've got pushed out of position on installation and blown out the mufflers, or completely melted and burned away from exhaust heat WTF!?????? .

      Would be almost Italian by design, to spec a regular O ring for a hot exhaust pipe, ensuring that it would melt away and become a regular maintenance item$ lol.

      I've located what I think is the right replacement O ring sold by Gutsibits in Europe, I've copied their picture and product description above.

      My balance pipe has an OD of 37-38mm,,,, but the O ring is meant to/designed to,,, sit tight inside the recesses in the female flanges of the mufflers.

      I'm hoping that someone here knows the exact dimensions AND best material for this O ring,,,, obviously the original was a piece of crap,,, or an extremely p*ss poor design. If you've found something local that works,,, or a McGyver fix,,,  please let know,,, I'm hoping to source these O rings locally,,, thanks in advance.

      Ride safe and take care

      Kelly

      Ps;, The FAC dampers / Wirth springs are now installed and finished,,, went through the tightening sequence in Guzziology, hopefully the forks are reasonably aligned and function smoothly,,,, had a bit of a hiccup shimming my brake calipers,,, I was going crazy trying to get them perfect,,, then I realized one of the rotors was slightly warped, that explained the varience in my rotor to pad clearance measurements,,,, had enough shims on hand to do a reasonable job, she'll be fine,lol.

      The IKON  shocks at the rear are halfway done,,, was a bit of a head scratcher doing a good install,,the washers supplied with the shocks didn't fit my mounting pins and the instructions were lacking,(but they recommended reusing all of the old hardware???) and researching WG was scaring me, I kept reading horror stories of guys mangling the rubber bushings in the mounts.

      Thank god I read some of the old timers on here, recommending to use the new big washers supplied with the shocks, to fully support the rubber bushings in the mounts,,, I used a round fiile to enlarge the hole in the new washers a bit,,, and they fit on my bottom mounting pin like a glove,,, the left over stock washer from the bottom was also used along with the stock top washer on the top mounting pin,,, I ended up with a nice tight install, top and bottom,,, with both rubber bushing mounts, fully supported on the sides with washer material,,, tks and gratitude to you guys on WG! "(bow)",,,, I haven't been able to get the fancy emoticons to work,,, so I'll just type it in,,, lol

[pete roper]

No, the reason they aren't there is because they have turned to ash and thence to dust and have been blown out and disappeared! Never in the history of exhausts has there been such a stupid idea as trying to seal a joint that will regularly see temperatures upward of 400*C with a nitrile O-ring!

Pete

[normzone]

What would be an appropriate material and format for that seal? Some kind of compressible titanium hollow donut?

[pete roper]

The best thing would be to not use such a bloody stupid set up in the first place and do what has been done with other systems since the dawn of time! Slot the larger diameter pipe and use clamps to compress and seal the joint!

Pete

[RinkRat II]

 If you have a good hardware supply they should carry  graphite impregnated  stem packing for faucets. Hi Heat resistance, easy to form and leak proof. Comes in various diameters to make your own rings.


   Paul B

[80CX100]

If you have a good hardware supply they should carry  graphite impregnated  stem packing for faucets. Hi Heat resistance, easy to form and leak proof. Comes in various diameters to make your own rings.


   Paul B

     Tks for the info, I'm going to try to source something pre-made, but if all else fails, I'll keep this in mind for a back up plan.

      tks

      Kelly

[80CX100]

No, the reason they aren't there is because they have turned to ash and thence to dust and have been blown out and disappeared! Never in the history of exhausts has there been such a stupid idea as trying to seal a joint that will regularly see temperatures upward of 400*C with a nitrile O-ring!

Pete

     I was afraid of that.

     I went back through my files and was able to find more information and Google then led me to HMB & Stein Dinse who are both supplying these O rings 38mm ID 40mm OD.

     I've given this information to my local NAPA guy,,, he's been good at sourcing odd ball O rings in the past, hopefully he can locate something in Viton, flexible copper or as Norm suggested some type of Titanium blend.

     It will be a challenge getting something durable, yet still flexible enough to fit inside the female flange and then pop back into place inside the recess,,, if I locate something local, that seems like it will work, I'll update this post for future reference.

     Tks very much for those taking the time to reply.

      Kelly

[Dukedesmo]

I recently had the exhausts off my LM2 and the 'O' rings had partially disintegrated although there was enough left to seal.


I bought some replacements from a bearing/seal supplier. I got 4mm cross section, 36mm ID and they are a perfect fit, I got Viton as they are better with heat than Nitrile,  they're only rated to 200 degrees C but Nitrile only to 120 C.


I bought a pack of 10 because I know they'll need replacing if I ever remove the pipes again...


UK supplier but these are what I bought; https://simplybearings.co.uk/shop/p514223/4mm-Section-36mm-Bore-VITON-Rubber-O-Rings/product_info.html?backstep=1

[80CX100]

I recently had the exhausts off my LM2 and the 'O' rings had partially disintegrated although there was enough left to seal.


I bought some replacements from a bearing/seal supplier. I got 4mm cross section, 36mm ID and they are a perfect fit, I got Viton as they are better with heat than Nitrile,  they're only rated to 200 degrees C but Nitrile only to 120 C.


I bought a pack of 10 because I know they'll need replacing if I ever remove the pipes again...


UK supplier but these are what I bought; https://simplybearings.co.uk/shop/p514223/4mm-Section-36mm-Bore-VITON-Rubber-O-Rings/product_info.html?backstep=1

     DD     Thanks very much for taking the time to reply and including the link of the ones you used.

     HHHmmm,,,, now you've got me really confused,,,

      Wondering why Stein Dinse and HMB would have them marked as 38mm id-40mm od(that cross section 1 mm does not look correct against the recess in the flange)

      The model you've given with a cross section size of 4mm definitely looks like a better fit for the recess in the female flange,,, but the 36 mm id would be a tight fit for my 38 mm balance pipe,,, that might be a good thing.

       Tks very much

        Kelly
     

[Dukedesmo]

Quote from: 80CX100 on Today at 04:21:25 AM

 

      The model you've given with a cross section size of 4mm definitely looks like a better fit for the recess in the female flange,,, but the 36 mm id would be a tight fit for my 38 mm balance pipe,,, that might be a good thing.

>

It is a good thing, if they were bigger I doubt you'd get the balance pipe into the flange. Mine are tight and need a little lubrication to go in, the 'O' ring is a nice snug fit on the pipe and the end of the pipe is lightly tapered to get it in. Then it's a nice tight fit once in.

Of course they'll burn/melt away again due to the heat (as previously mentioned, who would spec an 'O' ring in an exhaust?) but at least it started out in there.

I had to remove my exhausts again a month or so ago as the flange on the (Agostini) header pipe broke off (they really were very poorly welded, plus the right side is not quite in-line so is under tension when fitted) and there was still some 'O' ring left in both sides.

I did previously fit some Nitrile 'O' rings (the first time the flange broke off) and they had completely disappeared when the flange broke again.

Slightly O/T but (in case you're interested) the first time the header flange broke off it left a 'jagged' edge which I rewelded but it didn't hold so the next time I got some rings laser cut from 2mm steel (originals were 1.5mm) and made a clean repair which seems to be holding up so far but I'm not impressed with the original Agostini welding...

[80CX100]

It is a good thing, if they were bigger I doubt you'd get the balance pipe into the flange. Mine are tight and need a little lubrication to go in, the 'O' ring is a nice snug fit on the pipe and the end of the pipe is lightly tapered to get it in. Then it's a nice tight fit once in.

Of course they'll burn/melt away again due to the heat (as previously mentioned, who would spec an 'O' ring in an exhaust?) but at least it started out in there.

I had to remove my exhausts again a month or so ago as the flange on the (Agostini) header pipe broke off (they really were very poorly welded, plus the right side is not quite in-line so is under tension when fitted) and there was still some 'O' ring left in both sides.

I did previously fit some Nitrile 'O' rings (the first time the flange broke off) and they had completely disappeared when the flange broke again.

Slightly O/T but (in case you're interested) the first time the header flange broke off it left a 'jagged' edge which I rewelded but it didn't hold so the next time I got some rings laser cut from 2mm steel (originals were 1.5mm) and made a clean repair which seems to be holding up so far but I'm not impressed with the original Agostini welding...

Hey DD,     Tks very much for taking the time to reply with a little more info and insight.

     I've located those O rings on Amazon.ca, (8 for $22?)so they are definitely available in Canada,,,

     I've sent the revised specs to my local NAPA guy,,, he'll probably go apesh*t with the change, not the first time I've dicked him around chasing parts for my old bikes, oh well,,,lol.

     Tks very much

     Kelly

[guzzista]

 My Agostini (?) l header pipe first  peeled away its coating as the engine was first warmed right before my eyes (even though extreme care was taken not to contaminate the coating), then cracked within 100 miles of riding. As per the O rings, a possible alternative would be some thin flat shim stock( kinda like car brake pad shims,which have to stand hi temps) used as sleeves to seal off the exhaust. My O rings have not disintegrated yet, but I will be working on a solution and post info