I wouldn't do it. The stock bike is lean enough already.

 

If it is a girl who goes topples it won't definitely harm your engine.

 

If it is a girl who goes topples it won't definitely harm your engine.

It could, in fact it could make it disappear, if your wife see's the pics

 

If you go toppless with no fueler will it harm the engine?

The gain is really small and there is no doubt your pushing more air through the motor so I wouldn't chance it without some sort of flash or at least getting the afr checked.

 

And here endeth the lesson.

 

I have been doing alot of reading on going topless, and, although half the guys warn against doing it without a flash or fuel manager, not one has said they have experienced or heard of people having issues running topless with the factory map.........hmmmm. Anyone actually have, or heard of, any bad mech issues while running this setup????

 

Anyone actually have, or heard of, any bad mech issues while running this setup????

That's a $7,000.00 question! Do you feel lucky?:broke:

 

Why even chance it?
Seriously.
Jim

 

What year is the bike? If it's 08 or later then it shouldn't matter at all. The ECM will hold 14.7:1 AFR, or throw a sensor out of range code if it can't. If it's pre 08, it probably doesn't matter until the throttle is open far enough that the reduced restriction of the airbox makes a difference. I don't know where that point is, but I'd guess it's somewher past 7k rpm's.

 

it's an 2006...pre 02 sensor...I think i'll do my changes this winter along with a dyno..season's too short here in Canada to have any downtime! You guys are right, why chance it.

 

been topless

Went topless all last year . bike sounds meaner at take off less responsive in mid gears no change at highway speeds.Bike ran alittle hotter ,Don't know why but i kept track on dipstick themostat.This year Im back with top on..I lost intrest in sounding mean at takeoff and decided responsivnes was more important.:dance:

 

Went topless all last year . bike sounds meaner at take off less responsive in mid gears no change at highway speeds.Bike ran alittle hotter ,Don't know why but i kept track on dipstick themostat.This year Im back with top on..I lost intrest in sounding mean at takeoff and decided responsivnes was more important.:dance:

probably because it was running leaner

 

Ya'll are funny.

 

It never occurs to "tuners" that air boxes are tuned like exhausts are. No airbox and velocity stacks are ok on a race bike tuned to make maximum power at WOT. A street bike at part throttle, accelerating and decelerating in traffic is a different creature with different tuning needs. The volume of the air box and the pressure waves that occur inside, along with intake length and exhaust tuning have to work together. But, you know, the engineers at Harley Davidson and Porsche who designed these bike, well, what do they know? Right?

 

I guess emissions have no grounds here? That is a HUGE hurdle for all engine designers. Convenient to forget that, right? These bikes are built to pass emissions first and foremost. So go preach somewhere else! The tuners are the ones that figure this out in real life situations... You think too much man. Common sense applies in more cases than you like to think. Everything is so technical with you.

 

I know when I go topless, it hurts my engine more because I have to go that much faster to keep ahead of the Big and Beautiful Harley gurls that try to get me!!

 

running topless does lean the motor out and hd is already running the motor very lean...even if i wasn`t running topless i would buy a tuner ( hd or master tune) and get the a/f right... the bike will run cooler and make more power at every throttle setting... and on our dyno the last bike that i did topless made 5 more hp compared to running the top cover... if removing the cover caused the bike to not respond to the throttle it is running too lean .... v-rod motors can and have been burned up running too lean...

 

v-rod motors can and have been burned up running too lean...

And every other type of engine ever made....I ran mine topless with just a simple breakout box (TFI) and never dynoed but seat of the pants said quite noticeable gains especially in the midrange.

The noise was too much so the top went back on with just a few holes poked in the front wall either side ofthe snorkel. Feels the same as topless and no annoying lean surge/cough around 2800 RPM. Perfect throttle response from 1500 RPM to redline,average 33-35mpg and I open it up often.

Good point about the engine not responding to increased airflow if it's alread way lean.

 

On the carbureted systems, reducing the vacuum at the venturi (by boring or oversizing the carburetor) caused the engine to automatically run leaner. The fuel was no longer pushed from the float bowl by the atmosphere as well as with a properly tuned venturi. Even a small change in the air filter would cause a change in the A/F mixture.

Then came pressurized, computerized fuel injection- no longer was a venturi needed at all. Add air by opening the throttle and the computer regulates the amount of fuel added for any given atmosphere or load throughout the full range of engine rpm. Control is so absolute that when the throttle valves are shut as completely at idle as is possible without sticking, the IAT adds just enough air to maintain the preset idle speed.

:helpme:Can someone explain to me how removing the top causes the fuel injectors to starve the engine in these modern systems? I know that you're not all saying that the decrease in plenum vacuum (by going topless) is somehow reducing the amount of fuel sucked out of the injectors, causing the engine to run lean. The injectors do not rely on plenum vacuum.

The only thing that I can figure is that you're saying that at a certain rpm threshold the airbox intake (the CFM of the snorkel) is too small to feed the engine as well as the stock throttle (CFM). The snorkel would then become the throttle. I admit that is true, but the gains would only be realized at WOT above that threshold rpm- certainly not in the midrange too. And that loss of airflow CFM at WOT/top rpm with the airbox intact would not be any more detrimental to the engine than closing the throttle valve to match.

Dyno sheet to back up your claims please.

 

A couple of points. The fuel delivery map that determines injector pulse width (how long the injector is energized during each injection event) is based on a known airflow for engine based on throttle positon and rpm and is determined from many hours of dyno running. If you do anything to the engine to change the amount of air entering it, then the amount of fuel delivered will be incorrect for that airflow.
Resonant air boxes are designed to use pressure waves inside the air box to increase midrange power. They do not restrict maximum power and cutting holes in the air box generally does not improve performance. Removing the air box lid eliminates the beneficial resonances that make good mid range power possible, and this goes a long way towards explaining why a topless V-Rod looses midrange throttle response. It is very logical.
Read this:

http://motorcycleinfo.calsci.com/Airboxes.html

 

hey, I've read part of that link above, and w/22+years in audio / video, I get what the author is saying about resonances and speaker cabinets and his relating that to modern airboxes...opcorn

 

hey, I've read part of that link above, and w/22+years in audio / video, I get what the author is saying about resonances and speaker cabinets and his relating that to modern airboxes...

The quoted article is referring more to Helmholtz cavity resonance. The VRSC engine uses intake runner resonance. I posted pictures showing the difference.

 

opcorn

 

good morning!
keep it coming boys!
:coff:

 

Does anybody know or seen what the Destroyer airbox looks like<?>

 

According to this thread there is no filter or airbox cover, i.e. open velocity stacks.

 

Just an FYI for those who may not know, Harley actually recommends going topless and also drilling holes in the bottom airbox as part of the instructions for their Stage II kit. That being said, I do believe it would provide an adequate performance gain (and not a deterrent) if the MoCo is recommending it as part of a performance upgrade (note they also mention an ECM recalibration as well, just like others in this thread.)

http://www.harley-davidson.com/en_US/Media/downloads/Service/isheets/-J04779.pdf

I run topless with a TTS base tune for my configuration and it runs great. Interesting tidbit, when I was completely stock, bike would run very lean as they do from the factory, so lean that my rear header pipe would often be glowing a dull orange when I shut the bike down for the evening (noticeable in little to no external light.)

I've since added tab slip-ons, amsoil air filter, went topless, and bought a MasterTune, using their base map for slip-ons and high flow filter. I've now got a noticeable SOTP gain, along with no more glowing orange head pipes. I'm assuming that when TTS created the base tune for 08+ VRSCs, they ran it topless as well.. but not sure.