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Help with tech question!

12K views 35 replies 11 participants last post by  Phil13 
#1 ·
I just installed the Screaming Eagle slip on with the baffle discs removed and the end cap off. I left 1 baffle disc on but no end cap. I started the bike, left it in neutral, and revved it up a little to hear it. When I twist the throttle the exhaust rumble cuts out for a quick second then roars as normal. Why is it going quiet for a half second when I first twist the throttle? Do I need to put the discs and end cap back on so it functions correctly? Or is this normal how exhausts work?

Please help as I am new to bikes and don't want to cause any problems with it.
 
#6 ·
Don't read too much into the exhaust note. It could be just a little lag between the time you open the throttle and its reaction time. As regards using a fuel management system, any free flow exhaust system makes your vehicle run lean......meaning it gets less fuel than needed. This in turn leads the engine running hotter than usual and can be the cause for a number of problems for the engine, and that's why, manufacturers void the warranty if you use after market exhausts.
In your case, with the removal the discs and the end cap, you're exhaust system has in effect become a free flow system, and it will cause the bike to run lean. Having said that, don't get too worried. If you are using the bike for short distances and city runs nothing will go wrong. If you are still concerned, go for the fuelpak 3. All your worries are over except shelling out a few extra dollars.
 
#7 ·
Fp3



The FP3 is an OK fuel management device It has a lot of bells and whistles on it IE bluetooth etc.
If you do not have a good Dyno tuner in your area it is a cheaper option The Super tuner also has a smart tune option. Both will get your bike to run OK.
When the bike is Tuned on a dyno with a good tuner he will correct the Volumetric efficiency of each cylinder at all throttle positions and RPMs whereas the FP3 and SE smart tune feature will get you close.
The Supertuner is the only device that will allow a Tuner to make permanent changes to your Fuel / Ign timing and more MAP in your ECM.
A piggyback system will be constantly lying to your ECM to make changes after it has determined that the fuel values are not within parameters.
Bottom line as I dont want to make this long winded (I am not trying to promote HD stuff Only what I know from experience works)if you Do Not have a reputable Dyno tuner in your area go with the FP3 (it will get you close.
Something is better than nothing an exhaust pipe change is Huge.
We ran a bike before and after having a FP3 and V&H Pipe installed and it gained only 3-4 HP.
I gave the customer a hefty discount to install the Supertuner,which he did ,he has to come back for the tune as he had an accident.But I will post the results as soon as I get them.
BTW Supertuner is at least double the price of a FP3.
Talk soon
 
#9 ·
Dont Know


I have never came across this product.
Do your research 1st see if they will guarantee it works .
There is a lot of S*** out there that may leave you stranded.
Keep up posted if you have good results.
I am going to start a new thread, and after I have Proof one way or another. If you have had your bike on the dyno PM me the results and your thoughts please I hate people getting ripped off.
Later
 
#11 ·
I pretty much understand what you are saying, but not totally.
I do appreciate your effort and sharing your experience and knowledge with us.

it's a bit of a hard stretch for me to even buy the fp3 and a slip on muffler, if the supertuner is twice the price, it really knocks me out of the game. I just cant afford to spend this amount of money on my lil bike. (maybe i'll buy a lottery ticket and wish real hard...lol)

I will not be racing my bike in any competitions or worried about maximum horsepower, I just want to be sure I don't burn up anything by just adding a slip on muffler.

on a side note and obviously nothing I could ever afford to do even if it was available, .....would be to add a turbo to this engine.....wheeeee !>:D now that would be awesome!....

I know dream on. :(
 
#12 · (Edited)
Rock270, Really appreciate your thought process. Absolutely spot on. If the aim is to get more power, then buy a more powerful bike, pocket permitting. The fuel management system should be installed only to protect your bike from damage if you have installed an after market free flow exhaust. I did it for better sound and not more power and I am sure 90% guys have done it for this reason alone because the factory Street 750 doesn't sound like a Harley. Fuellpak3 is more than sufficient to ensure a richer mixture into the engine to prevent damage and is therefore more than competent for the purpose. I wouldn't advise spending extra money on remapping or better tuning options. Moreover, merely remapping or tuning by itself will not give appreciable advantage in terms of horse power. There is a lot more which needs to be done alongside to achieve the gains one wants. Rest, the choice is with each individual.
 
#13 ·
the way I understand it with the fp3 installed it will initiate a map when the key is first powered on, then in the auto tune mode it will constantly check for any updated maps on the v&h data base of maps via the internet and put in place what is needed for that bike under real time conditions.

these are probably pretty close all in all, but if one wants competition performing top horsepower then the more advance and specific programmers with dyno tested specialized maps will be needed for absolute peak performance.
 
#15 ·
Typically a slip on muffler isnt going to be a problem for your bike, now if you add a hi flow intake with that hi flow muffler you will need a download at the least. So dont mess with the muffler baffles or plates if you arent tuning it., my bike has a fp3 on it I haven't messed with it, time to see if I can manually remap it.
 
#16 ·
I installed the SE Nightstick slip on but I removed the baffles and end cap. It backfires now. I just ordered the FP3, does that mean I can now add the hi flow intake? The fp3 does NOT have a MAP for SE nightstick with baffles removed. Will it even work? I just ordered one but can return it.
 
#20 ·
Ok, I'll add my 2 cents here. If you only did a slip on, you have not increased air flow through the system because you have not changed out the stock air cleaner. A tune may not be required at all. When you say backfire, do you mean a loud bang, or just decel popping? If it's just decel popping, that was probably already there, you just couldn't hear it with the stock pipe.
The FP3 writes a map to your ECM, after backing up your stock HD map. The FP3 does not have to say connected to the bike once the map is flashed. It is awesome however to have a tach, gear position, and other goodies displayed real time on your bar mounted phone.
If you don't have an exact match for the equipment you added to the bike listed in the FP3 app, just select something close. A high flow filter is generic, they all work about the same. I highly recommend you change out the stock filter to a HF, and then use the FP3 to flash a map. This will help performance, sound, and let the motor run like it should, not stupid lean as delivered from the factory. I noticed big differences when I did this. No HP numbers, but trust me, you can feel it.
The FP3 has an Autotune feature to further refine your setup. Leave the FP3 plugged in, start Autotune, go ride a lot until the grid in the Autotune is properly populated, then flash the bike with that new map.
 
#25 ·
It's "decel popping" I beleive. Not like a loud explosion from grandmas old honker of a boat too wide for the drive through haha. So if I have a free flow exhaust (removed baffles and end cap from after market pipe) and if I add the high flow AC ... Could I just pick "stock exhaust with hi flow AC" for the MAP even though it's not a stock exhaust? I'm not looking for more torque or anything. Just want the engine to run well.
 
#35 ·
I'm late to the party when it comes to the FP3. I have done the auto tune several times and it seems like my bike doesn't run right when its cold. After it reaches 185 degrees, then the hesitations go away. Really noticeable when taking off in first gear just after start up. Some days when I go for a ride, the bike temp will not get above 170. I still have a stock intake and I have a Fire Brand Loose Cannon with a DQ baffle. Today, I flashed back the stock map. I have over 28,000 miles on my 750 and 23K with the Slip on muffler and DQ baffle. I do like seeing the tach and other readings on my android phone while listening to tunes through my helmet. Any suggestions on eliminating the hesitation after flashing an auto tune would be helpful. Lowering the the temperature from 195 to 170 didn't eliminate this hesitation issue. I literally had to let the bike warm up to 160 degrees before the hesitation in the throttle response went away. Is this how it works?
 
#36 ·
Use the FP3 app to contact Vance and Hines and explain what's happening as you have here. You can upload the FA map you're using and they will check it and then tweak it as necessary before downloading it back to you. They are usually very quick to respond.
 
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