Power Mods: Exhaust, BJM, and Intake Box

[SwitchBlind360]

First I wanted to thank Wicked Webby for his threads on this subject and for answering my many questions through email.

Second, I think the FJR came with plenty of Horsepower and Torque from the factory, but I really enjoy modifying and customizing (making it my own....one of a kind), and well, if the power can be made safely and inexpensively, then why not add some.

The right side of the airbox has a nice lip inside to hold the air filter in place. Once the cover (left side) is reinstalled, it forms a great seal and the filter stays securely in place. I really like this set-up because it was very simple to do, and maintains the use of the stock or stock-like K&N air filter. After 4 days of trial and error, I set CO numbers (via barbarian jump mod) to 34 across the board. If you don't cut a hole in the right side of the airbox, your #1 cylinder will run rich unless the CO number to that cylinder is reduced. It should be noted, too, that I am running GPR race mufflers with custom mid-pipes. Factory headers and catalysts are still intact.

Once I receive my K&N and throttle body synchronizer, I will be going into the Harley shop to fine tune and post my stats on their Dyno. I really like going in there with my "crappy foreign" bike and posting up numbers they would have to spend thousands to get with their bikes :yahoo:

Cost:

K&N Filter - $62.95 shipped

GPR cans - $211 shipped (but I sold my stock cans for $200)

SS Mid-pipes - $55

1.75" exhaust clamps - $19.95

Time on Dyno $100 (hopefully it only takes an hour)

 

[SPORT]

Nice work!

This looks more like what I would like to do.

Couple questions:

1) What do you mean by 'Trial and error' when setting the CO? I've done the Barbarian mod for my Gen I FJR and it has worked well. Just trying to feel out how you discovered the 'best' CO setting for your air box configuration.

2) To clarify, if you cut the right side of the airbox as you described, do I 'assume' the CO's should ALL be set to the same setting (whatever that 'best' setting may be).

Looking forward to your full report.

btw: what is the reason for the red duct tape?

Thanks

Sport

 

[keithaba]

btw: what is the reason for the red duct tape?

Cause red is pretty, duhhhhh!

Nice work, my modification for more power was purchasing a blackbird!

I'll be interested to see what the dyno numbers come out to.

 

[Wicked Webby]

SwitchBlind360,

Glad I could help you out. Looks like you did a good job for a nice setup. Let me know how your dyno time goes.

Take care,

WW

 

[ARFJR]

Where did you get that sweet CF fender?

 

[SPORT]

Where did you get that sweet CF fender?

Read the bottom of his post and you'll find a web link

 

[SwitchBlind360]

The red tape: Due to the modification of the left side of the airbox, there was a big hole on the front of that cover. From the looks of it, that cover was designed to aide in keeping water off the plethora of electrical harnesses (and in my case, provide an attachment point for the YCCS fluid reservoir). In order to maintain the first function, the hole needed to be covered. Red tape is what I happened to have sitting there at the time.

The fender: I work for a small company that makes small carbon fiber overlays, one-offs, and carbon replacement pieces- mostly for auto interiors. My bike got backed into last fall and the fender was cracked. Rather than having Yamaha replace it, I just covered it in Carbon. Therefore, its not a functional piece....just for looks.

The CO numbers: I originally cut out the left side only. I thought at that point that all cylinders would be getting the same amount of air, so I evened out the CO numbers (got that from WW). Once I started increasing the numbers, there was a point when the idle started becoming rough, and I was getting a small backfire on decel or downshifts to high RPM. For some reason I thought to try dropping the number one cylinder before I dropped the rest of the CO values. I dropped a few points off #1, and the bike idled smooth again and no more backfire.

Once I cut the hole out of the right side, the idle was a little rough again again and I noticed a little lean pop at decel so I evened them out (also based on WW's threads), and it all went away. Trial and error without any objective measuring devices is definitely not a great method to tune a bike for your particular intake and exhaust set-up. The only thing that is fairly obvious is that a free-flowing exhaust and intake will require more fuel than original factory defaults. One can surely get closer than that with trial and error. Perceived power output, exhaust sounds, etc., but the only way to know for sure is with a tail sniffer or a dyno, or preferably both.

So as far as CO numbers go: Its assumed that, 1) by having holes on both sides of the intake that the cylinders will be receiving closer to even amounts of air, 2) that the intake combined with a more free flowing exhaust will flow better, hence requiring more fuel to all cylinders, and 3) Information provided by Barbarian Modders is correct in that Yamaha default values are on the lean side to begin with. There is not too much trial and error. Start at +7 and add fuel until you can feel the "rich" stutter when gunning it at low RPM, then back it off a little. None to scientific, which is why, once I change a couple other things in my system, I'll go play on the Dynomometer.

One last thing, there are certain sounds that engines make (through the exhaust and intake) that are present only when there is little or no back pressure in the exhaust system. Because my bike now makes those noises, I am assuming that the cats/pipe design does not cause a lot of restriction to the system. This makes me feel that gutting them is really not worth it....plus I can rationalize that I am at least a little bit "green"

 

[SPORT]

SB360,

Thanks for the clarification.

Looking forward to your dyno test. Do you have any base numbers to compare the airbox/exhaust mod with?

 

[RTSR1/FJR]

I would think that the scoop would help supply cooler air to help keep the ECU cool by evacuating the hot air more so than water.

 

[SwitchBlind360]

I would think that the scoop would help supply cooler air to help keep the ECU cool by evacuating the hot air more so than water.

Thats hard to say. That does make me think though. Take a look at that entire piece and truly....what was the purpose. I posted what I thought it was for, but also, really look at it maybe it was just for the intake noise.

When you remove it, there is still the inner "horn" of the air duct. However the cover adds even more of an airway and for about 4 inches, provides a "double wall" for the intake path. I can only think of one logical reason for this and that is for insulation (specifically, noise reduction).

So I guess as far as leaving that hole open or covering it, its up to you based on which you think provides some advantage.

 

[user 8909]

I would think that the scoop would help supply cooler air to help keep the ECU cool by evacuating the hot air more so than water.

Thats hard to say. That does make me think though. Take a look at that entire piece and truly....what was the purpose. I posted what I thought it was for, but also, really look at it maybe it was just for the intake noise.

When you remove it, there is still the inner "horn" of the air duct. However the cover adds even more of an airway and for about 4 inches, provides a "double wall" for the intake path. I can only think of one logical reason for this and that is for insulation (specifically, noise reduction).

So I guess as far as leaving that hole open or covering it, its up to you based on which you think provides some advantage.

I removed mine (05 model) and made a rubber boot to cover the cpu plug.

Did the Barbarian mod after that and noticed a big difference, MPG is about the same as before just much smoother at low end.

 

[jstewart]

switch I took the same course you did after reading WW's report on his airbox mods. I was already using a K&N filter and a set of Staintune slip ons when I opened up the right side of the airbox. I was also already using a power commander before opening the airbox. I did the barbarian mod after modifying the airbox and put a zero map in the power commander to compare the two. I have concluded it will take a dyno tune to get a correct map for the power commander. I tried fiddling with the power commander cells on the custom map I was using before the airbox mods but there are just to many variables without a dyno. So far the barbarian mod has produced the best seat of the pants results on my 05 FJR. That may change when I get a chance to compare the two on Ryan Schnitz's dyno where we can do a proper dynojet map. I suspect most of the benefit from using a power commander will come from being able to lean out the low throttle position settings for better gas milage while leaving the extra fuel in the mid and upper throttle settings. To say the least the results so far are impressive for the effort & expense. If I get a good dynojet map for the airbox mod that produces better results than the barbarian mod I will share it with anyone who wants it. Not sure how the map may apply to a gen 2 FJR though??

 

[RTSR1/FJR]

You guys are going straight to "HELL" for desecrating the Sacred FJR for HP improvements! WW was crucified and then drawn and quartered for doing it! Don't you realilize Yamaha engineers were scraficed to the gods for that airbox? Can't be improved [SIZE=8pt](At least that's what they say, whoever they are!) [/SIZE] [SIZE=10pt]![/SIZE]

 

[Karl]

You guys are going straight to "HELL" for desecrating the Sacred FJR for HP improvements! WW was crucified and then drawn and quartered for doing it! Don't you realilize Yamaha engineers were scraficed to the gods for that airbox? Can't be improved [SIZE=8pt](At least that's what they say, whoever they are!) [/SIZE] [SIZE=10pt]![/SIZE]

I'm all for power mods on the FJR since I have done exhaust mods (removing cats mainly for heat reduction), aftermarket cans, K/N, and dyno tuninglink programming on the PCIII. But based on my experience with other bikes, the airbox is kind of a touchy deal especially on a sport tourer like the FJR. While I have no doubt that the 100% throttle peak power may be improved with cutting holes, I would be concerned about loss of smoothness and linear torque across all riding conditions. The box is matched to the cams and messing with the resonance/tune can truly result in peaks and dips in partial throttle power that you can feel. It would be interesting to see a full dyno analysis at various conditions to see how rideability is affected or not from this "improvement".

 

[Chris G]

Karl

I know exactly what your getting at. I had an 86 VFR and read on the VFR list about cutting the airbox lid for big HP gains. With a spare lid i cut it up, the bike would fall flat on its face through the rev range unless it was wide open. It was jetted and had a full system on it but really needed the air box volume to carberate properly.

On the other side of the coin, my 900ss has an open airbox and with pipes and jetting it really wakes the bike up.

Switchblind360, keep forging ahead!

 

[Wicked Webby]

Karl,

Sounds like you should read my thread on all of this... The FJR's air box has no tune for power.. (Just noise reduction)....

The Velocity style intake tubes within are the only things tuned for performance...

WW

 

[Gramps]

I would think that the scoop would help supply cooler air to help keep the ECU cool by evacuating the hot air more so than water.

Thats hard to say. That does make me think though. Take a look at that entire piece and truly....what was the purpose. I posted what I thought it was for, but also, really look at it maybe it was just for the intake noise.

When you remove it, there is still the inner "horn" of the air duct. However the cover adds even more of an airway and for about 4 inches, provides a "double wall" for the intake path. I can only think of one logical reason for this and that is for insulation (specifically, noise reduction).

So I guess as far as leaving that hole open or covering it, its up to you based on which you think provides some advantage.

I removed mine (05 model) and made a rubber boot to cover the cpu plug.

Did the Barbarian mod after that and noticed a big difference, MPG is about the same as before just much smoother at low end.

Hey KIEEFER, you got a pic of the boot you made?

I've also done the exact air box mod on my '05. I do not have after market pipes, but do have a PCIII & K&N filter. It goes in on Wed. for a little maintenance & re-tuned on the Dyno. Prior to the air box mod the bike was dynoed at 122 hp & around 87 ft. lbs. of torque if I remember correctly. So I should be able to see what the kind of increases the air box mod alone will get me. I'll report back.

 

[radman]

I would be more reluctant to modify an air box feeding carbs than I would one feeding FI, which is more or less self adjusting, whereas carbs are not.

 

[Wicked Webby]

Gramps,

I am looking forward to hearing the results of your dyno with the added air/fuel with your PWC. I really do suspect, as we talked, that you need to open up the output (exhaust) to really benefit from the extra air/fuel. Remember.. You can only take in as much as you can put it out. Those stock pipes maybe bottle necking you from getting great gains.... It is nice that you have had a baseline run done before on your bike (I assume your going back to the same dyno)... Let me know how she does!

Anyone here have a set of slip-on's Gramps can buy up CHEAP!?!?

Switchblind360,

Since you have exhaust too.. It will be interesting to see your dyno results (not compared to mine, so much as a baseline run back to back with your modded runs.. as I did.. Remember different dyno's read differently) of your mod of having the larger holes cut in both sides of the air box while retaining the stock style air filter element. BTW, I had the right side of my air box duct taped up, along with an extra (stock) left side air box cover on for my base runs.

https://www.fjrforum.com/forum//index.php?s...hl=wicked+webby

You can order the extra left side air box covers from Ronayers.com for around $15. As we have talked about, I wonder if you will have enough of an air opening... To get the results I did.. You just might.... I hope so... The theory being... A naturally asperated motor can only breath in soo much.. So whether you have a set of med doors (as you have created with your drilled out box) or a set of x-large doors(as I did with my dremel'd out box). Thus, if your getting enough air your getting enough whether its from a med door or an x-large door. I found that the more air (with the right amount of fuel) the better with my research. Remember, to have your under the seat left/right side plastic covers on during tuning and dyno runs because they do restrict the amount of air intake(a lot). You want your bike tuned on the dyno the way it really will be rolling down the road. Unless your gonna ride it with the under seat side covers off.

WW