Moto Guzzi Exhaust

[Mikecocos]

Hi guys,

Would like to solicit your input. Riding home from work today my 2014 V7 Stone lost power.  I took a good look at the bike and noticed white smoke coming out of one of the screw holes of the heat shield in the left exhaust muffler. I took the muffler off and noticed some significant discoloration on the muffler. I am assuming the loss of engine power was caused by the exhaust fumes not clearing the exhaust, due to an issue with the muffler.   

I have attached a couple of pictures below for context and info. You'll note from the picture that I replaced the Stone exhaust mufflers with V7 Racer mufflers. I did not replace the exhaust gasket (GU91113826) - as the used gaskets  were still in good shape. Know that I purchased the V7 Racer exhaust used from someone that had his exhaust replaced with Mistral mufflers immediately after purchasing his bike  - so the mufflers were practically new when I purchased them.

You'll also note that I wrapped my exhaust.

Anyone have any idea of what caused the smoke? Did the baffle wrap catch fire in the muffler? Or, Is there something caught in the muffler? Is this potentially related to the exhaust wrap (the exhaust fumes being too hot for the muffler)? Short of buying new mufflers is there anything I can do to fix the issue.

Any help here would be appreciated. I am at a loss.

http://s483.photobucket.com/user/mikecocos/media/IMG_1552%202_zps25ec76mk.jpg.html?sort=3&o=0

http://s483.photobucket.com/user/mikecocos/media/IMG_1551%201_zpszxainbqr.jpg.html?sort=3&o=1

http://s483.photobucket.com/user/mikecocos/media/IMG_1486%201_zpsjdsoyb0d.jpg.html?sort=3&o=2

[pete roper]

Crappy plug caps. It's not firing every power stroke and the expelled fuel is burning in the Cat. XD05F, (From memory?)  NGK caps will fix the misfire. The cat is permanently compromised.

Pete

[Mikecocos]

Wow... you're good. That makes sense. So replace the plugs and the covers - correct?

Also, are the cats really unusable? A quick explanation would be nice. I ask as they are pretty expensive to replace.

[Dave Swanson]

Here is a short article addressing the plugs and caps with recommended replacement part numbers.

http://www.motointernational.com/service/tech-update-all-single-throttle-body-moto-guzzi-v7-models

[Mikecocos]

Thanks Dave. That looks more or less exactly like my issue.

Any opinion on whether the mufflers are salvageable?

[pete roper]

The cats are made of a honeycomb material, in a situation like this they will clog, melt or degrade rapidly. It's very likely thay will be seriously degraded.

The good news is that many people swap out their original mufflers for aftermarket ones. If you ask nicely you'll probably find someone who'll sell you their originals for a song.

Pete

[Mikecocos]

Thanks, Pete. I was able to track down a used pair at a reasonable price.

Impressed with the solid knowledge available on this forum.

Thanks.

[sturgeon]

On mine, the plug wire was touching a small spring clip on a hose hidden behind the head on the right side. It started shorting the plug lead which led to the same problem you describe. The raw fuel burnt up the catalytic converter. Luckily, the dealer replaced the exhaust under warranty. Same effect as a bad plug cap.

[Toecutter]

Mine did the same thing.

Lost the right cylinder, massive surging... cooked my right exhaust pipe. Plug cap was shot, and the mapping had gone to hell.

[Mikecocos]

So I just picked up new NGK CPR8EA-9 sparkplugs and new NGK XB05F sparkplug caps. If I want to confirm that the caps caused the problem - what should I be looking for in the old the plugs and caps?

[Mikecocos]

So i just finished replacing the plugs and covers.

Thought I would share some thoughts.

The old plugs and plug covers didn't show any signs of arcing. At least to my untrained eyes. I attached a couple of pictures for comments should anyone disagree.

Interestingly there was a rubber washer missing on the left plug which is the same side on which the muffler is severely discolored. I suspect this may be related - something like water getting into the plug and causing arcing or shorting. 

I did not adjust the spacing of the NGK CPR8EA-9 plug.

I also mounted the spark plug into the new plug cover (NGK XD05FP) before screwing it into the cylinder.  This was the only way to get the spark plug and plug cover with both washers into the cylinder. The plug cover didn't tighten fully in the cylinder i.e. the plug cover kept turning indefinitely - is this supposed to be the case?

I also find the connection with the cable end  flimsy - a bit of movement and the cable end will disconnect from the plug cover. Any tricks about how to improve that connection?

See some pics below.

 http://s483.photobucket.com/user/mikecocos/media/IMG_1553%202_zpsbcaicajt.jpg.html

http://s483.photobucket.com/user/mikecocos/media/Left%20cylinder_zpsnw7wfypi.jpg.html

http://s483.photobucket.com/user/mikecocos/media/Left%20plug%20and%20cover_zpssbuunxhu.jpg.html

http://s483.photobucket.com/user/mikecocos/media/left%20wire_zpstorhflpt.jpg.html

http://s483.photobucket.com/user/mikecocos/media/Right%20cylinder_zpsjjdqmzux.jpg.html

[Howard R]

It's hard to tell from the photos, but it almost looks like there could have been some arc damage at the top of the old boots.  I don't mean to sound harsh, but you really need to hook up with someone who knows what they are doing.  It sounds like you are using the friction from the rubber part of the cap on the ceramic of the plug to screw the plugs into the heads.  That won't get the plugs anywhere near tight enough.  Those plugs need to be properly torqued, probably somewhere around 20 ft-lb, your owner's manual should have the correct value, and that can't be accomplished with the caps on the plugs.  Also, the wire end of the plugs sort of screw onto the wires.  If you take a light and look into the end of the cap, there is a threaded metal post (kind of like a wood screw, with a tapered point and coarse threads) which screws into the conductor of the plug wire.  It should feel pretty secure when you get it on correctly.  You might have to cut a centimeter or so off of the cable to get a "fresh" end to get the cap to tighten up, especially if the old caps had been loose for a while and "wobbled" out the center conductor of the wire.  Finally, depending on the new plug caps you might have to remove the connector from the plugs to get them to fit.  Those silver "barrels" will usually unscrew, leaving only the screw threads on the top of the plug to go into the caps.  (You might have to hold the hex of the plug with a wrench and use a pair of pliers to unscrew the barrel.)  It all depends on the type of connector the plug cap is designed for, some are made to fit the barrel and some caps are made to fit only the threads.  Again, look carefully up inside the business end of the cap with a good light to see what type you have, and maybe try a test fit with both plug & cap in your hand to verify.

Hope this helps.

Howard

PS to add:
You said you did not change the gap of the new plugs, but did you check them?  Those plugs probably fit a number of different bikes, and the plug manufacturer cannot know what particular gap any bike might need.  They could be correct right out of the box, or they could be wrong for YOUR bike.  (I have found both cases.)  ALWAYS check the gap on new plugs to make sure they are correct, again the owner's manual should tell you what you need.