reassembling the exhaust system

[vuzzi]

I'm reassembling the exhaust system and run into some questions.

 

First, I noticed that I have to push up the crossover (behind the gearbox) quite a bit in order to fit it to U-shaped bracket. So the bracket really puts some pressure on the exhaust system. I wonder how the bracket and the crossover should fit. Just loosely or pretty thight (pussing the cross over up 1 cm)?

 

And how about the clamps. As thight as possible (say 30 NM) or loosely?

 

Thanks for any help.

[docc]

It helps to loosen all the clamps and fasteners from the heads all the way to the hangers, then hook every thing up loosely before tightening it all well from the front to the back. The idea being to reduce strain on the exhaust especially where it fastens to the head. It's a good time to clean up threads with a wire brush and apply copper anti-seize, particularly the head studs.

 

With that, it may still take some wrangling especially with some of the aftermarket crossovers or canisters.

[vuzzi]

It helps to loosen all the clamps and fasteners from the heads all the way to the hangers, then hook every thing up loosely before tightening it all well from the front to the back. The idea being to reduce strain on the exhaust especially where it fastens to the head. It's a good time to clean up threads with a wire brush and apply copper anti-seize, particularly the head studs.

 

With that, it may still take some wrangling especially with some of the aftermarket crossovers or canisters.

 

OK, thanks. I'll start thightening from the headers.

How about the crossover hanging in the U-bracket. Should it hang loosely or should it be pushed up?

[docc]

On the stock crossover there is a 3,5 cm rubber spacer and a harder 1,5cm spacer between the bottom of the U-bracket and the tab on the crossover. This all bolts up tight. The harder spacer goes next to the exhaust (above the rubber).

 

A picture is seen on page L-6 of the Workshop Manual for the Sport.

[docc]

Like so:

[vuzzi]

Like so:

 

Allright. But how much pressure should there be on the rubbers? Should it lift the crosssover up 1-2 cm?

[docc]

I don't think mine went together with that much strain. One centimeter doesn't seem so bad, but I'd be afraid 2 cm might strain the connection at the head. Is there still that much misalignment with the system all loosened up? Are all the parts stock?

[raz]

It helps to loosen all the clamps and fasteners from the heads all the way to the hangers, then hook every thing up loosely before tightening it all well from the front to the back. The idea being to reduce strain on the exhaust especially where it fastens to the head.

I use to re-do the above, except the head flanges, after running. That is, riding a couple of miles and then let it idle a couple of minutes so everything is really hot. Loosen all clamps, hit joints a couple of times with a rubber mallet, retighten. It seems to result in less strain.

[vuzzi]

I had the head flanges fitted just so that the headers can rotate left-right in order to position the crossover in the centre.

 

In that way there was a mismatch of just over 1 cm. I just bend the connection at the crossover a bit so there is only little upward presure. Parts are stock except for the muffers, but they don't have an effect on this matter.

 

What should be the goal of loosening and retightening after heating the system up? Differences in thermal expansion between alu and steel?

[raz]

I had the head flanges fitted just so that the headers can rotate left-right in order to position the crossover in the centre.

 

In that way there was a mismatch of just over 1 cm. I just bend the connection at the crossover a bit so there is only little upward presure. Parts are stock except for the muffers, but they don't have an effect on this matter.

My 1100 Sport is not exactly a V11 but it has a very similar design and similar mismatch/stress on the rubber mounts (but more front-aft stress than up/down). The RH pipe between crossover and muffler also tends to touch the brake pedal unless I wiggle and jiggle for half an hour. I chalk it up to imperfect design.

 

What should be the goal of loosening and retightening after heating the system up? Differences in thermal expansion between alu and steel?

A little of that, but more because my joints are really tight no matter how I try to clean them or sand them. The heat makes everything much looser so it can settle in the least stress position. Maybe the need for this is less on V11's, I don't know.

[docc]

It is the same on the V11.

 

Vuzzi, since your crossover seems to be low, it will be good to clean all the connections and be sure the pipes, both fore and aft, are pressed fully in. This might require removing the head tubes to insert them into the crossover, rather than trying to push the crossover up onto them.

[vuzzi]

It is the same on the V11.

 

Vuzzi, since your crossover seems to be low, it will be good to clean all the connections and be sure the pipes, both fore and aft, are pressed fully in. This might require removing the head tubes to insert them into the crossover, rather than trying to push the crossover up onto them.

 

The pipes were pressed in pretty much all the way. However, when loosening the clamps after a ride and hitting the joints a few times, the crossover moved back a bit. It would be nice to have the pipes and the crossover connected (held togheter) with springs in stead of thight clamps. I'll check the possibility of that at a local garage. For now, i'll press the crossover back on the pipes when hot, and that would do for now.

Thanks for the ideas for now.