I have an ‘07 1200 Sportster that I bought last winter. The bike has a K&N air filter and unbaffled Vance & Hines drag pipes. It’s also EFI- I’ve never owned a fuel-injected bike before.

So, when trying to “lope” somewhat quietly through a town at low speed/barely-cracked throttle, the bike will occasionally sputter and run strange. If I downshift and raise the rpms a bit, it’s fine. Just happens at barely-cracked throttle.

Any ideas what might be the problem? I don’t know if anything has been done to the computer. I’m assuming that more air (K&N filter allowing more air), and better breathing exhaust might mean that it needs some sort of EFI adjustment to add more fuel, and I suspect this was never done. Theories?

Question- how do I get this diagnosed? If it IS the computer, what does it cost to replace with one modified for my intake/exhaust situation?

Many thanks!

 

I THINK its a fueling thing. An imbalance from what I have read. Not sure how to fix.

 

Perhaps lugging?.....however, me think the bike is not properly tuned, especially with unbaffled drag pipes ie not enough fuel at lower rpms

 

Fuel Pak needed. There are several models available and several threads about the topic. I am not experienced with them so can not offer a recommendation but someone will pitch in soon. Search for Power Commander or Harley Fuel pak. I think they are several hundred dollars.

 

Mine did this too, and I have been "tinkering" with my ViED system to balance the cylinders, going by plug color. The ViED system allow for each cylinder to be adjusted independently. I know a good tuner would be more accurate, but so far it seems to be helping.

It has helped, but I still get some sputter, not nearly as bad.

 

I called my local HD dealer and he said no charge to read your ecm and see if it has been tuned. I would try maybe a TTi and see if that helps too. Start cheap, then work up.

 

Ummm, what’s a “TTi,” if I may ask? 😬

 

You are lugging the motor. Sportsters don't like low RPMs cruising like the big twins. They like to be revved. This is not good for your crank bearings and other parts..

 

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