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Discussion Starter · #1 ·
Hello All,

I'm new to motorcycles as of spring last year. My '04 919 is my first motorcycle, and I'm glad I jumped right in. I've been racing cagers for years now, and am affluent mechanically but still an amature at it.

I've ordered a pair of Yoshi CF slip-on's and have already replaced the air filter with a DNA. I've already noticed a difference in the exhaust tone, and amount of breathability moving through the engine.

My question is: Once I put on the Yoshi's do I need to install/purchase a Powercommander? I understand that I will not be getting everything that I can potentially get from my new setup, but would rather spend some money on some new handlebars, some ss brake lines, and/or some turnsignals. Eventually I will buy a PCIII usb, but would like to hold off.

Does anybody see any downside to running my new intake & exhaust configuration without the Powercommander?


Thanks in advance,

Phil
 

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Usually the computer can compensate for the extra flow. You might experience more popping and back firing on decel. This can be remedied by removing the PAIR system. For best result I would say power commander and a custom map. The biggest change is the low and mid with a custom map. It smooths out the throttle response.
 

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The extra flow means that your bike is intaking more air without an adjustment to the fuel being distributed to the injectors. Honda, and most manufacturers, tend to run the bike lean (not enough fuel) from the factory to pass emission testing. When you use a freer flowing airfilter and better flowing exhaust you allow the engine to "breath" better but it will need more fuel to maintain the Stoichiometric ratio otherwise known as the air/fuel mixture ratio that is optimal for both performance and engine longevity. I would suggest that a power commander would be a wise investment if you want to maintain the longevity of your bike.
 

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Discussion Starter · #4 ·
Thanks for your responses so far. Both are informative and helpful in making my decision.

I likely do not want to change the emissions system as suggested in by TuonoR6. It sounds like a solution to a particular problem.

The affects of the air/fuel (Stoichiometric) ratio based on factory setting as mentioned by Shaughnessy is a very good point.

I will probably hold off on the brake lines and riding gear to get the PCIII.

Final question. Should I get a custom dyno tune from my local shop so the mapping is correct?


Phil
 

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I say custom is the best way to go. Each bike is a little different and location affects the tune slightly also. You might find a map on WT and some tweaks it may run perfect.
Never skip gear for performance items. It may save your kister. What are you looking for as far as gear I might have some stuff
 

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After installing my exhaust, I took my bike to a Dynojet Authorized Tuning Center (from the website) and just had them check the A/F ratio at several points and they said I really didn't need a PC3. I was more worried about long term damage than eeking out any extra power. I'm sure it's not as optimal as it could be with a PC3. They only charged me $50 to test it, and said if I needed a PC they would apply that towards the cost of the PC3/ Tuning.
 

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After installing my exhaust, I took my bike to a Dynojet Authorized Tuning Center (from the website) and just had them check the A/F ratio at several points and they said I really didn't need a PC3. I was more worried about long term damage than eeking out any extra power. I'm sure it's not as optimal as it could be with a PC3. They only charged me $50 to test it, and said if I needed a PC they would apply that towards the cost of the PC3/ Tuning.
where you using the stock filter..thats good to know about not needing the pc3
 

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If you dig into some threads you will find out that the 919 runs rich from the factory. An aftermarket filter can hurt your performance. It creates too much turbulence in the air box. If you plan on continuing using the filter and have the slip ons it is not necessary to install a pc3 , but I personally recommend it. I have one and I noticed a good difference and even my wife who only is on the bike once in awhile commented that it ran better and had better response!
 

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Discussion Starter · #13 ·
Where can I find a map for this combination? Filter & slip-ons. I'm not willing to drop another $300 on a dyno tune.

Anyone else have this combination? DNA air filter & CF Yoshimura slip-ons.
 

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Discussion Starter · #15 ·
No worries about the gear. Just have to make some different choices, since the Yoshi's arrive on Friday, and I'm not returning the DNA airfilter. Maybe I'll just use the DNA on track days (whenever that will be - since I have no intentions on doing that - I won't say never).

Is it worth $250 for a custom tune being offered at a local shop? I don't go crazy on my 919 anyhow.

Still wondering if anyone has a similar setup, using an a/f mapping in their pc?
 

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Discussion Starter · #16 ·
Thanks to all who have weighed in, but I am still a bit confused.

I'd like to understand more about the risks of using the aftermarket air filter. It's affects on a/f ratio lean/rich detrimints to performance and engine life. Does the affects of increased airflow and the increase of turbulence in the airbox affect performance and engine life?

mdastrider stated:

"An aftermarket filter can hurt your performance. It creates too much turbulence in the air box. If you plan on continuing using the filter and have the slip ons it is not necessary to install a pc3,.."

and...

Shaughnessy stated:

"When you use a freer flowing airfilter and better flowing exhaust you allow the engine to 'breath' better but it will need more fuel to maintain the Stoichiometric ratio otherwise known as the air/fuel mixture ratio that is optimal for both performance and engine longevity."
 

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for a 919 you will not need a custom map or PCIII with slip-on pipes / Air filter. The 919 runs SUPER Rich from the factory and the addition of pipe/air filter will only very slightly modify your A/F ratio. I've run with slip-on's, with out pipes at all, my current 900rr set up and stock. None of which were anywhere close to being in the dangerously lean department. Save the money and buy gear!!!

When you have a little extra green in the wallet, get a PCIII and have a custom map made on a dyno with a sniffer. I'll bet money that you will be told it is not necessary, but could benefit you with improved throttle response and drive ability.
 

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Since I don't own a 919 I am not privy to how the mixture comes from the factory only give you generalizations for most motorcycles. Most motorcycles come quite lean from the factory to pass emissions.

I must disagree with the statement that an aftermarket airfilter will cause turbulence in the airbox. If the aftermarket air filter is of the same size and dimension as the stock filter, It will have no effect on the swirl that exists in the airbox. The filtering action happens just as the air is sucked into the down tubes leading to the throttle bodies.

I highly recommend having your bike tuned. If you are willing to spend $350-$450 on a power commander, why not spend the extra $250-$300 to have the tune that is right for your bike. Each bike is different enough that while someone else's tune may get you close, a custom tune can compensate for variables that exist from bike to bike.
 

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I highly recommend having your bike tuned. If you are willing to spend $350-$450 on a power commander, why not spend the extra $250-$300 to have the tune that is right for your bike. Each bike is different enough that while someone else's tune may get you close, a custom tune can compensate for variables that exist from bike to bike.
Exactly!

If you are running exactly the same set up as someone else... you can easily get by with running the map they had made. (yes some small variables are unaccounted for, but its free)

This why it is so important that if someone does get custom tuning, you should share it. Kind of a "Pay it Forward" type mentality. Eventually there would be maps for just about every type of bike and set up.
 
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