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Discussion Starter #1
I have a 58mm throttle body on my bike i was running 4.22 injectors the bike was not smooth up to 30 mph i put 5.3 injectors in the bike now it runs smoother i was wondering if the 4.22 were not letting enough fuel in at low speeds
 

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Low speed shouldn't be the issue and the stock injectors should be sufficient up to all but the peak power. Larger injectors are needed at higher throttle openings when the injectors can't flow enough to support the airflow and power created by the motor. Injector duty cycle can be measured on a dyno. Generally if you are breaking 80% duty cycle on an injector you should bump up to the next larger size. Since you are running the ThunderMax the issue may be that the base tune has been designed with the larger injector in mind.
 

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I used the stock injectors on my 58mm TB and didn't have any issues so I would think it would be in your base map. I had to use a base map for stock injectors.
 

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Yes they do but any build that HD has also states for "RACE APPLICATION ONLY" so that means you are running full throttle more often than not.
The stock injectors work just fine with a 58mm TB if you use the right EFI map and the only thing it would affect would be the top end performance.
In all reality the 50mm TB works just fine on any 103 stage 4 build.
 

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Yes they do but any build that HD has also states for "RACE APPLICATION ONLY" so that means you are running full throttle more often than not.

The stock injectors work just fine with a 58mm TB if you use the right EFI map and the only thing it would affect would be the top end performance.

In all reality the 50mm TB works just fine on any 103 stage 4 build.

That makes sense. HD's guidance is kind of misleading in that both pre-2014 103 stage IV kits come with the 58mm TB. Both are expected to produce upwards of 100hp, but only the race application comes with the bigger injectors.


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Discussion Starter #9
My bike makes over 100 hp i didn't notice a gain when i changed my injectors just ran better a lower speeds might be because of the cam 585 with higher compression
 

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Have you dyno'd the bike yet?

The only difference that you will find from the larger injectors is a slight change in peak HP. Low speed manners are tune related. The stock injectors are more than sufficient to feed enough fuel for the lower RPMs.
 

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Discussion Starter #11
No dyno my bike makes the same hp and tq as dragos build the same build its hard to find a tuner in my area that does thundermax I am sure the bike is making more hp and tq because the last time on a dyno my ecm was bad the afr was 19 in the front cylinder i got that fixed
 

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Joe before you go and compare kits here and ones that are not tuned yet.

We build 4 different 107 kit.

Here are 2 sheets

Dragos 2.0 with less compression than yours 10.3.1 comp 580 cams

Dragos 2.8 Kit with more work than your kit 11.2.1 with our new prototype 600 cam



=SMOKENJOE;3134802]No dyno my bike makes the same hp and tq as dragos build the same build its hard to find a tuner in my area that does thundermax I am sure the bike is making more hp and tq because the last time on a dyno my ecm was bad the afr was 19 in the front cylinder i got that fixed[/QUOTE]
 

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No dyno my bike makes the same hp and tq as dragos build the same build its hard to find a tuner in my area that does thundermax I am sure the bike is making more hp and tq because the last time on a dyno my ecm was bad the afr was 19 in the front cylinder i got that fixed
No dyno? And you are SURE that you are making more hp and TQ? You were sure about the power you were making until you had your bike dyno'd in Laughlin. How did that work out for you?

Joe, you came on here asking about injectors because you just switched them. Did you do anything to the base map in the ThunderMax? You can't just change a component like injectors and expect everything to just adapt without telling the ECM what has been done. And if you are using a custom base map from Frank that uses the stock injectors, and then you switch the injectors out, a whole different base map should be loaded. Even then, you can't roll a bike up on a dyno and expect a bike to perform exactly like one in Frank's shop that has had a custom tune.

Back to the original question. The stock injectors are plenty capable of delivering sufficient fuel for low speed and the fact that it was running rough at low speeds is tune related. The stock injectors are insufficient to deliver adequate fuel at peak HP assuming the bike is set up to deliver much over 100hp. If you are having low speed rough performance you should review your tune or tuner. If you switch to different injectors you also need to review your tune or tuner. Switching injectors without switching the tune will result in reduced performance due to incorrect fueling.
 

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Discussion Starter #15 (Edited)
DRAGOS I SAID MY BIKE WAS ABOUT THE SAME AS A 106 YOU BUILT SORRY I SAID THE SAME YOU ONLY TUNED THE BIKE MY 106 MADE 109.9 HP and 115.37 Torque WITH A BAD ECM I WOULD SAY THAT IS CLOSE TO YOUR 106 TUNE HERE IS A QUOTE FROM YOU
http://www.roadglide.org/54-dyno-results/235402-not-happy-2.html
Here is one
Here is a 2012 With the a set similar set up as yours.
79CC S&S heads
106 S&S kit
58 MM tbw
S&S 640 cams
Rinehart Extreme duals
Thundermax Tuned 100% by Dragos.

We did not build motor. Just tuned the bike.

For some reason I am having a hard time down loading picture.
But it made 108/109HP and 118/120Tq

Desertwndrr
YES I APPLIED FOR THE NEW INJECTORS IN THE MAP THE T MAX HAS AN INJECTOR SIZE COMPENSATION
 

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i did not say a ruff idle said bike was not smooth at 0-30 mph i am sorry i started this thread
Not smooth = ruff does it not? just asking. Sometimes its the simple stuff. can of wd40 and 2 sec.
The reason I'm asking is if it had a intake leak it would be gulping air that it shouldn't and bigger injectors may just compensate for it.
It's not like Harleys have the best intakes sealing system out there.
 

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There is a wole bunch of thing that could contribute to your Not Smooth" 0-30mph before ya changed injectors.

The map that was loaded into your T-Max may have been set up for the 5.3 injectors in the 1st place. There is a option in the T-Max to input the size of injectors if they are not what the base map is.

If you never had the bike on a dyno, it really needs to be. Even the T-Max needs to be set up on a dyno. It will only tune AFR, not timing. Tuning on the street is not the same thing as tuning on a dyno.

But what do I know? Here is my 200Hp SG with a T-Max
 

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There is a wole bunch of thing that could contribute to your Not Smooth" 0-30mph before ya changed injectors.

The map that was loaded into your T-Max may have been set up for the 5.3 injectors in the 1st place. There is a option in the T-Max to input the size of injectors if they are not what the base map is.

If you never had the bike on a dyno, it really needs to be. Even the T-Max needs to be set up on a dyno. It will only tune AFR, not timing. Tuning on the street is not the same thing as tuning on a dyno.

But what do I know? Here is my 200Hp SG with a T-Max
Did you finally get 200hp out that bike?
 
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