Comeback for under-seat exhausts?

Honda patent - Comeback for under-seat exhausts?

Honda has filed a patent for a V4 sports bike with an under-seat exhaust similar to those popular a couple of decades ago, signalling a possible return of the fashion.

Racing bikes began using under-seat exhausts in the 1970s for a number of reasons: to cut drag, improve balance, place the outlet in the bike’s vortex for more efficient gas exit, increase lean angles and make the exhaust long without curling the pipes.

All very admirable technical reasons.

But when famous Italian designer Massimo Tamburini designed the Ducati 916 in 1994, the world was won by the beauty of the bike.

Motorcycle design
Ducati 916

Pretty soon other Italian manufacturers jumped on the bandwagon and even the Japanese followed suit.

But like all things fashionable, it largely died out in the mid-2000s. The only remaining example we can think of is the beautiful MV Agusta F4 with its four “organ pipes”.

MV Agusta F4 RR
MV Agusta F4 RR

On a practical level, manufacturers believed it was more important for handling to centralise weight lower down in the bike. Under-seat exhausts were not only hot on the backside, but also placed the weight too high in the bike, making it difficult to handle.

So stubby under-bike exhausts became prominent.

Now, stringent Euro4 emissions targets require massive exhausts which simply won’t fit under the seat or under the bike.

They are ugly as sin and the worst offenders are the new Suzuki GSX-R1000, Honda Fireblade SP and Kawasaki H2.

2017 Suzuki GSX-R1000
2017 Suzuki GSX-R1000

However, Honda may have found a way around the ugly exhaust syndrome.

They have filed a patent for bike with both an under-seat exhaust and a side exhaust as we have sen on some race bikes.

It is believed it will be used on a V4 sports bike Honda is building to celebrate its 70th anniversary.

The Honda design uses a complex muffler system with a single under-seat pipe for the rear bank of cylinders while the front two use a traditional side exhaust.

Honda patent - Comeback for under-seat exhausts?
Honda patent drawings

One thought on “Comeback for under-seat exhausts?

  1. Whilst assembling the Lego BMW, had to lay-by it due to financial constraints, we got talking about how manufacturers/aftermarket suppliers could ‘enhance’ the look of the muffler by designing the muffler to flow with the bike eg: colour code to match the rest of the bike, – one of the better examples was on the GSX 750/1000 which looked like a machine gum barrel, -like! – 2017 Triumphs have a good enough system, clever too.
    out Sydney way saw a heat shield with Danger Hot stamped on it in red, wasn’t sure if he was referring to the Bike or the pipe …. (oh got the model for the children, honest. )

    42063 BMW R 1200 GS Adventure – Products – LEGO® Technic – LEGO.com – Technic LEGO.com

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