modified exhaust # - potential motor damage?

Hi all,

I am hoping to join the ranks of VFR owners soon.

I am going to look at a very clean, low miles (6,000) 1998 VFR in a few days.

My only concern with the bike is that the owner has modified the exhaust replacing the muffler with a straight pipe right off the header. (pic below)

I am sure the bike will be loud as hell. I would plan to replace this setup with a more conventional muffler immediately.

My question is: could running this setup have damaged the motor in any way and what should I be looking for to test that. (I am talking about things I could look at or listen for in a parking lot, not taking the bike apart.)

I know a bit about older bikes, inline 4s and vtwins but have never had a sportbike or even anything fuel injected.

Thanks for the advice, I hope to be posting pics of my new baby soon.

-b

 

I'm not sure whether you would be able to tell if there was damage or not. Not running a muffler reduces backpressure on the exhaust valves and CAN lead toward exhaust valve problems. I can't say that I know anyone around here that has run straight pipes on their 5th/6th gen VFR. If you were looking at a late 5th gen (00-01), I would say that you wouldn't have to worry about it as the catalytic converter provides most of the backpressure in the exhaust system however you are looking at an early 5th gen (98-99) without a catalytic converter.

If the bike were to run fine whiletest driving it, I would probably go for it myself. You wont be able to hear the valves too much as I'm sure the straight pipes will be too loud to hear the valves tapping or anything of that nature. The 5th/6th gen engines are pretty bulletproof and they will take a lot of abuse.

 

You're concerned that all of the blind, retarded soccer-moms driving F350s will be able to hear you??? - Dude, loud bikes save lives.

 

requiring back pressure is a myth. back pressure is bad and exhaust valves get burned by lean jetting or mapping, not from lack of back pressure.

 

Don't know about you. But that looks bad ass to me. And it shows off the sexy swing arm! It is, like Norcal said, a matter of fuel-air mixture and how she runs. Don't be scared. It's a Honda

 

It USED to be that short and open exhaust pipes could cause exhaust valves to warp, as cold air had a more or less straight shot at the exhaust valve(s) when the motor was shut off. If they warp slightly, they do not seat evenly and are not able to transfer heat to the cylinder head which could cause them to overheat & burn. That may be ancient history, however; metals have evolved a lot. I only mention it as a remote possibility of potential concern.

They exhaust pipe would have to be pretty short, I think, and the valves would probably have to be off their seats for it to be a real issue.

End of history lesson. :smile:

 

so i guess, as soon as you shut of the engine you would be willing to grab a hold of the header pipes? would you be willing to do it 5 minutes after you shut the engine off?

 

The only time I have ever even heard of that possibly happening is if you ran the engine for a long time with no pipes on it whatsoever. But I have never actually seen it happen.

 

Well what do ya know... I learned something new today.

Edit: its late and im tired... what i'm trying to say and ask isn't coming out right. guess i'll just have to try again tomorrow or forget about it.

 

thanks for all the replies guys. So I guess I wont worry about motor damage, just going deaf. I am going to see it Monday, hopefully everything will work out.

 

Having a Two Brothers exhaust on my bike, it sounds awesome. The thought of me listening to your bike with a straight pipe at 10,000 rpm just makes me giggle and smile!!:hump:

 

No worries ML. A better explanation for what happens is that removing the backpressure from the exhaust system allows the cylinders to empty more completely before the exhuast valves close (there is actually a term called reversion that gets involved, but I won't go into that here). This exact process is why it is necessary to rejet or remap when a stock exhaust sytem gets replaced by an aftermarket full, race type, exhaust system. I'm sure you will do the research so I won't drag this post on any longer.

 

my 5th gen is pretty much straight piped, no problems, sounds like a Alcohol drag car , Will run REALLY rich until it warms up in cold Round 0 C... BACK-PRESSURE IS MADE FROM THE HEADERS AND COLLECTOR, or cat if ya still have one on your bike Mostly the Headers, U should have it remaped, or get a TFI fuel injection manager or powercommander with exhaust changes. 5thgen engines r bullet proof....its the willies JEEP of the moto world in my opinion Oh ...and quit buying disposable ear plugs cause u will go thru a box or 2 a month

Edit : Cops here r cracking down on the noise or bikes...ive goten a few Fixit tickets.... i slip on my 2 bros take it to inspection say it was the pipe on the bike and the cop was a dick... it of course passes... go home throw on the exaught tip that i call a muffler, and bobs your uncle till next time

 

It is the select few that cause laws to be inacted for the many. put a proper exhaust on your bike, squid.

 

ummmmm....NO...wait wait thinking some more.........................no

 

thats a myth IMHO ..
Ever been around a jet engine.. way louder than ANY BIKE
ever been to an air show??if a plane flies over head and its not loud till its OVER HEAD...
how the HECK is a freakin car.. 500Feet head of u on the road gonna hear you loud pipes save lives is kinda bunk to me.. i just like the way it sounds ... lets admit it we like loud exhausts..lets not justify it because it keeps us save.. if ur going 100mph on the highway NO exhaust is gonna be able to warn the cars ahead of u your comming

 

Well, since it is a 4 cylinder engine, you could point one pipe to the front, one to either side and one to the rear. Then nobody will know if you're coming or going.

Just kidding, of course. An amusing thought.

 

Totally agree.

Loud pipes should never take the place of safe, yet defensive riding skills.

If you ever grew up by the tracks (bad or good side!) you will know standing at the apex of a curve in the track with equal limited viability on each side you will hear the train for quite some time but will not be able to determine the direction it is coming from. In many cases you will only be aware of where it is coming from when it is in sight. This is without interference of engine noise, radio noise,kids in the back seat, a cranked stereo system, cellphone conversation, the dampening effect of sound through the car/suv/hummer itself or simply a blank mind.

Also low frequencies of sounds are good at penetrating objects and continuing onward but the direction of the source of sound is very hard to determine. On the same page, high frequencies of sound do not penetrate worth a damn but you can distinctly tell where the sound is coming from. the human ear is good at detecting the direction of higher frequencies but cannot distinguish the origin of lower frequencies in the spectrum. This is why when you setup a 5.1 home theater system the placement of the satellite speakers is critical while they tell you to put the woofer against the wall somewhere in the room.

Loud pipes do not save lives. They create more distractions for the overly distracted motorist!

 

I wasn't going to be the first dick to chime in on the "loud pipes save lives" comment but now that others have addressed it I will put in my two cents as well.

Loud pipes save lives is a gimmick drummed up by the Harley riders as an excuse to let them have whatever annoyingly loud pipes they want on their pieces of shit. Period. End of story. There is absolutely no scientific evidence that can back this up and by the time someone can hear it you are almost surely too close to them for them to be able to react or spot you.

If they were really all that concerned with saving lives they would be more than happy to put on a damn helmet. I can point you to plenty of evidence that proves helmets do save lives and I don't think a single person out there can dispute this fact. But of course arguing that helmets save lives would mean that they would lose that potato potato potato sound that they cherish oh so dearly and it would make some of their bad ass image disappear. They can't have that so they will try and pull of what they can.

Topping it all off is that these idiots are going to screw it up for everyone. Yes, loud pipes are nice and so are the sounds that can be brought out with a few modifications. However there is a limit that is within reason and what is tasteful. There is no reason to have your bike sounding like a MotoGP bike unless it is on the track and at that point you either need to have a dedicated track bike or a spare slip on that you can change between your track and street riding. Loud pipes save lives will end up screwing all of us in the end that want something other than the stock exhaust. It is slowly getting out of control because more and more are doing just what the OP showed done to the bike. There is nothing to help keep the annoyance factor to a tolerable level. There will be bans and laws nation wide to regulate it and it will affect more than just our bikes. All vehicles will be hit by it and then we will all be pissed because Joe Dipshit thought it was cool to wake his neighbors up at 4AM while going out to the garage and listen to his straight pipes while bouncing it off the rev limiter for two minutes straight to get it warmed up fast.

As Ron stated above it most certainly is the select few that cause laws to be inacted for the many. Now grow up and be tasteful with a little bit of class.

 

Is the key here "full" exhaust system? I recently got a great deal on the TBR Stash slip-on from a member here and the main reason I bought it was that the gains (as little as they are) were supposed to be "bolt on" according to TBR. No remap or power commander required.
Below is the Dyno chart from TBR for a '02-'07 VFR with a stock exhaust system with stock mufflers vs stock exhaust system with a TBR Stash slip-on. As you can see, it smoothes out a bit, but no significant or measureable gains until 9,000 RPM.

http://www.twobros.com/Cust_Service/Dyno_Charts/Hon_VFR800FI_Stash_Dyno.pdf

Is a PCIII a waste of money at this point? Will increased gains be had? Or not till a full system has been acquired and installed?