exhaust question...

[GaryFrank1959]

Lo all,

I read somewhere that its not a good idea to mess with the headers....

I'm considering chopping my '99 but don't like the way the collector sits underneath the motor.

What would happen if I made my own headers.

I saw some pic's of a 5th gen with 2 cans on either side - thats what I'm hoping for....

[Stray]

My limited understanding is that headers are quite precisely calculated so the exhaust pulses reach the link point at the right times. 

 

Getting it wrong means pulses collide and some might flow backwards destroying the scavenging function of the exhaust and leading to imperfect combustion. 

 

If you do chop your headers at least do it after they join. So configuration would be 4-1-2. Split the pipes after the central union. 

 

Lots of sports bikes run 4-1-2 so it’s a good configuration. 

 

From your description it sounds like you are maybe talking about the catalytic converter under the engine. Maybe a set of cat-less headers would be right up your street? Delkevic do them and early 5th gen OEM headers also have no cats. 

 

Stray

 

 

[RVFR]

Ah a  good ole header???   To a point yes they are calculated out in flow charismatics to get the best mid range  On the norm Honda has it for the general public where mid range power is where the v4 lives, so in turn Honda made it the way it is just for that.  Now the other part is getting the rear and front to work together, why they meet under the engine he way they do.  I've thought long and hard about what you are thinking with a twin set up like the 86 vfr.  But.. the swing arm is in the way, an add Honda made the rear ports facing right to help avoid the collision there, other wise,  like Aprilis v4  with for the most part using a traditional swing arm,  it would be easy.  in this case , not so much.

[VFR Capt.Bob]

Dual exhaust cans add unnecessary weight to an already portly 5th gen.  On my Tuono it created a burn hazard to my calf when remounting the bike after a brief stop like at a gas station. I have been branded twice by mine. 

Even my 86 vfr700 ended up running much better with a 4 into 2 into 1 slip on and jet kit. 

I think 2nd and 3rd gen VFR existed during the heyday of creative after market exhaust systems. They had over under twin exhaust and left exit exhaust systems that catered to the SSSA. 

The new tech is to put all the weight and heat pollution low and under the bike. That is where i think it belongs too.

[Rogue_Biker]

I wouldn't mess with those headers.  From what I've been told, the '98-'99 headers are desirable since they are of slightly larger diameter and therefore flow slightly more than later year VFR's.  The 1998-1999 VFR800's made the most power when compared to the later VFR's.  Over 100 rwhp.  My 6th Gen only made 98 rwhp, and the newer 8th gen VFR800's made even less...around 96 rwhp.  "Customizing" your headers and putting a dual exhaust in your VFR is a sure way to lose horsepower AND torque.  

[JZH]

I've never seen a pic of a 5th gen with dual exhausts.  It probably can be done, but the SSSA tends to get in the way.  Honda used to run dual exhausts on the RC45 superbike, but they also switched to a conventional swing arm (possibly for unrelated reasons).  Many years ago I picked up a dual-sided exhaust for my NC35, which I have never managed to fit, but I've always liked the look.

 

Anyway, I doubt Honda spent much R&D on maximising performance.  They knew that no one would be racing a stock 5th gen VFR...  They did spend time on the Y2k model's exhaust, but that was to allow them to use a catalytic converter and not lose any performance, compared with the non-cat '98-'99 model.

 

But if you can make your own headers, I don't see why you couldn't have a go.  The OEM headers clearly weren't made for display, so there is some room for cosmetic improvement.  But I don't think very many people out there have the skills to make something much nicer than Honda's effort.  Surprise us!

 

Ciao,