About to try to fix crossover leaks.

[Flay]

I'm going to start in on my exhaust air leaks tomorrow. Dealers have had at it but after a few rides, they're always back again (along with the "popping and banging"). All the bolts seem tight enough but my test paper strips still flap in the breeze :S.

Anything I should keep in mind when doing this? I'm assuming the (dis)assembly will be straightforward enough and I've purchased a tube of Permatex Copper to seal everything up with.

The headers are fine, it's mostly the crossover and slip-on's I'll be paying attention to.

Any tips appreciated!

 

[NOLAGuzzi]

If it is a breva the heat shields are SHARP. I take the whole bracket off so that I don't need to remove the shields.

 

[russ in pa]

I have just come to accept the popping on deceleration because of engine braking but I did have an annoying backfire every once and a while. Adding a PCIII and having it custom mapped did not seem to help. The one thing I have noticed though the backfire has not happened for quite some time and about the only thing I can think of is I did change the crossover to the Stucchi. The stock crossover is big and hollow as I think this helps with the stock mufflers with the cats. Going to the Stucchi did however change the exhaust sound however in the first one or two gears as it makes more of a "blat" sound when backing of the throttle to shift gears. I also have FBF slip-ons.

 

[Flay]

I just noticed a trend. The more leak from the left-side crossover junction, the more popping I get. It can get bad enough I have people ask me whether they're "something wrong with my bike" and sometimes occurs just when cruising along, not gearing down..

I've gone the PCIII/Mistral route and it didn't make any real difference, except to make the offending sounds more noticible. Though everything else is much sweeter.

Well, the gasket goop is curing now so I'll know tomorrow whether this all worked.


russ in pa wrote:

I have just come to accept the popping on deceleration because of engine braking but I did have an annoying backfire every once and a while. Adding a PCIII and having it custom mapped did not seem to help. The one thing I have noticed though the backfire has not happened for quite some time and about the only thing I can think of is I did change the crossover to the Stucchi. The stock crossover is big and hollow as I think this helps with the stock mufflers with the cats. Going to the Stucchi did however change the exhaust sound however in the first one or two gears as it makes more of a "blat" sound when backing of the throttle to shift gears. I also have FBF slip-ons.

 

[jest2dogs]

Flay,

Did the goop work? No more word on the popping...

Did you say you you had a Stucci crossover? How's that working out? Worth the expense?

I have a 2007 Breva with stock pipes and stock mapping and no exhaust leaks and no popping or backfiring. Lucky I guess. I was considering the Stucci crossover for two reasons:1, because it would make the tranny oil change easier, and 2, because I've heard it will change the exhaust note a little (ripen it :O).

-Jesse

 

[Holt]

Sure the leak is from the crossover? I'd guess it's from the righ header pipe/muffler joint. At the design stage someone forgot to take into account that the cylinders are offset, and ordered header-pipes of the same length for the next 10 years assembling, so that the right muffler does not really reach the tube ....
(Which also is the explanation to the different height of the mufflers)

I mounted a Stucchi crossover couple of monts ago by the same reason, reaching the gearbox draining plug. Yes, it gives a new note, but don't expect the old ladies to lose their false teeth when you pass.

 

[Flay]

It ended up being a long journey.

In short, yes, the Permatex Copper did work and minimized the popping. Screwed up the first time by putting a bead around the inner join when I should have smeared an wider swathe with the goop. Second time the charm. Fixed the obvious leaks on both sides of the crossover and the slight one where the Mistral slip-on's join. But the bike still ran rough, was hard to start and popped.

-Turned out the fueling was buggered. After running a VDST "Fuel Pump Test", I'd open the gas cap and listen to the suction pop. A solution was beyond me so I took it to a mechanic who replaced, changed and re-routed the fueling (brass instead of plastic fittings). Only "bad" thing is that the return from the charcoal cannister now vents below the bike (sorry EPA!). Amazing difference, like getting a new bike.

-Pulling off a freeway stint, I noted a metallic "jangling" sound from the right side. I'd broken a exhaust header stud right off and the other bolt had flown away too. It was just hanging there. Luckily I was two blocks away from a gentleman with several loop frame bikes. He got me back on the road and I got the studs/bolts replaced. I probably had a leak there for some time, contributing to my popping issue.

- Replaced the battery with a (really expensive, wow) Gel type. Bike starts with a touch of the button now. I was dubious when the mechanic said to ditch the stock unit but, as usual, he was right on the money.

Everything seemed fine, so I re-installed the PCIII with Mistral slip-on map. Ran fine this time and finally sorted out the various (and apparently normal) fueling stumbles.

Mechanic says it's the best running 750 he's taken a test ride on.

I might consider the Stucchi crossover next time I'm "down there", but with the Mistral slip-ons, I have all the sweet exhaust note I can handle at the moment. Enough that I get people running up to me after groups rides with wide grins on their faces. And that's with the baffles in! .

Flay,

Did the goop work? No more word on the popping...

I have a 2007 Breva with stock pipes and stock mapping and no exhaust leaks and no popping or backfiring. Lucky I guess. I was considering the Stucci crossover for two reasons:1, because it would make the tranny oil change easier, and 2, because I've heard it will change the exhaust note a little (ripen it :O).

-Jesse