BREAKING: new 4 in 4 exhaust

[franov_imp]

Hello guys!

guess what.. our friends from Busso Silencers just wrote in the Italian CB1100 owners Facebook group that they'll be working during the upcoming winter season on a new 4 in 4 exhaust system!

really hope they'll make it "cb 750 four style" and of course with the possibility to maintain the center stand: it would be the only one in the world with those properties!

fingers crossed...

[peterbaron]

Good luck and fingers crossed.
Update us accordingly!

[Houtman_imp]

That would nice and another option.

[PowerDubs_imp]

My favorite style is the Moriwaki 4-4. It has the cleanest lines and angles.

I don't want a sandcast style flange seamed muffler.

I will not buy an exhaust that makes me loose the center stand. There is no reason it can't be done.

If they were able to include not only the 2 OEM sized O2 bungs- but also 2 smaller WBO2 bungs to give us the option to install the Dynojet power commander without having to custom weld- they will have my sale, and a writeup not only on the install but dyno result comparisons as well.

Pass that on.....

[franov_imp]

I'll tell them! btw I think that currently the best looking ones are the wyverns with their classic look, but still didn't buy them mostly because center stand had to go, and I would never be able to give up on it as I think it's one of the most important accessories to be fitted to every motorcycle, both for maintenance and security.

[whizzle_dizzler_imp]

Any word on pricing?

[franov_imp]

still nothing for the moment: only thing I can tell is that the slip on silencers (4 in 2, similar to the stock ones) are about €600 VAT included; don't know how much the same ones cost in the USA with the monetary exchange, taxes etc.
I don't think they'll make the 4 in 4 cost more than €800 (if just slip on silencers) or about €1200 (complete with headers) as they are generally quite good with their prices even if the product is 100% artisanal, therefore taking a lot of craftsmanship

[Charlie Bravo_imp]

I'd be interested in a 4 into 2 like on the early 90s 750 Nighthawks. Hmm, a search may be in order...

[Paris_imp]

I'd be interested in a 4 into 2 like on the early 90s 750 Nighthawks. Hmm, a search may be in order...

I saw a huge jump in torque and an extension of the power curve when I replaced the 2 into 2 stock exhaust on an '81 CB750F with a 4 into 1. As I understand it, there is a big advantage using a 4 into 1 over even straight pipes if it is tuned correctly. The exhaust pulses traveling down the header create a vacuum which scavenges more exhaust out of other cylinders.

[Roper_imp]

I'd be interested in a 4 into 2 like on the early 90s 750 Nighthawks. Hmm, a search may be in order...

I saw a huge jump in torque and an extension of the power curve when I replaced the 2 into 2 stock exhaust on an '81 CB750F with a 4 into 1. As I understand it, there is a big advantage using a 4 into 1 over even straight pipes if it is tuned correctly. The exhaust pulses traveling down the header create a vacuum which scavenges more exhaust out of other cylinders.

I have heard this before, but I have a hard time visualizing it.

As exhaust travels through the headers, it remains in discrete pipes until the collector. So any vacuum created in the header behind the exhaust pulses wouldn't affect the other cylinders, whether it's 4-1 or 2-2.

In an I-4 engine, the outer two cylinders move together and the inner two cylinders move together.

With a 2-2 exhaust, when one cylinder is on its exhaust stroke, the other is on its power stroke. I suppose there could be a vacuum created in the collector to help "scavenge" exhaust from the other cylinder in the millisecond the valves are open. The exact same thing is happening on the other side.

With a 4-1 exhaust, the same thing is happening, but in pairs. Sure, there is double the exhaust volume which may create a larger vacuum, but it's also "scavenging" exhaust from double the cylinder volume at the same time. The ratios don't change.

So, I'm either misunderstanding something, or there's something else going on that I haven't taken into consideration.