Now that spring has shown it's face here in Upstate NY, I've had a chance to ride my 06 Lowrider after the recall has been completed. Last fall I had SE II's installed with AC and download. I haven’t had the new injectors installed yet. Everything seems well but occasionally when I get on the throttle a bit and then let off quickly, I get a quick pop/back fire. Anyone else experience this? Is this something I should be concerned with or is it the nature of the beast???

 

You need the 25 degree injectors. There are many threads on this subject and Harley Service bulletin M1185. Search on this topic and read about it befor you go to the dealer.

 

25 degree injectors will not keep your bike from popping or backfiring as the previous post said. He is pushing those injectors on everyone. Granted they will help for certain bikes with certain conditions (mostly Touring models) but if you aren't experiencing any of those conditions then they will do nothing. Many of us have 8 degree injectors that work perfectly fine.

What you have is a lean condition that can be solved by a SERT and or dyno tune with the appropriate ECM/Fuel controller.

To a very small extent it's also the nature of the beast but you are most certainly on the lean side.

 

you think the dealers would have a lean price and a running good price on the bikes on the show room floor.oh i forgot the new bikes have the 25 degree ones in them cause it fixes the problem

 

the 25 degree injectors fix the lean problem because the flow rate is higher than the stockers. 4.89gm/s compared to 3.92gm/s. BUT, a sert or power commander will also fix the problem by dyno tuning and adjusting the flow rates to make the bike run richer.

 

Correct me if I'm wrong here. But myself using several different types of EFI in drag cars and doing custom map programs on dynos.
How do you determine you have too small of an injector when the motor is only right off idle? If the injector were too small it would show up in the high RPM range in the pulswidth ratings by the injectors going full static (100%), lower RPM's indicate a tuning issue more than an injector issue because of the acceleration enrichments are tuned wrong, or at least tuned to run lean and as far as EPA goes, Lean = Clean.

 

Those are max values. Injectors only flow/pulse enough fuel which is dictated by the fuel table map and VE tables so peak numbers are not a good indicator. It's the dispersion of the injectors spray pattern that is the question. Does the wider spray cone create a richer condition? Most likely not but it may atomize the fuel better and make for easier starting and smoother running. Just a thought.

Pops on decel? Welcome to owning a Harley. I've yet to have one carbed or injected, EPA limited or fully tuned that did not do this to some extent. Just part of the vibe.

 

I completely argee the spray pattern of the injector has alot to do with it, however I dissagree about having to replace all the injectors to the 25's. I was one that purchased the SERT and through many hours/days of tuning and trying different things my bike runs great with the stage1, big shots, stock 8's with a SERT. Don't get me wrong, I wish as much as anyone that Harley would have gotten this fixed from the get go, but if we think Harley's 25 degree injectors are a cure all then we're sadly mistaken because it still has to meet EPA specs so the bike is going to run in the same range it always did, the spray pattern may help a low RPM stumble or surge but it's the same tune up, Lean is Lean.

 

when you change the stock #8 injectors out to the #25 injectors, it WILL richen the fuel ratio. the 25 degree injector has a higher flow rate than the 8 degree injector AT ANY THROTTLE POSITION. the bikes ECM is programed as to which injector that it is working with until you tell it different. the ECM thinks it is using the smaller injector, so it cycles the injector for a certain amount of time, but actually it is using the larger injector that flows MORE fuel for each pulse! SO GUESS WHAT? THE BIKE RUNS RICHER! if there are any doubts as to what i am saying look at the tuning constants table in your SERT. it will ask you what flow rate injectors you have. that way, the ECM knows how long to open the injector for the injector size that you have...

 

Yes, you are correct about the injector values effecting the pulse in the injector. But my point was, either way, the EPA wins in the end regardless of injector in a closed loop system. If we are talking '06 Dyna, the o2 sensors are trying to pull the mixture to 14.6:1 kicking and screaming regardless of if the injectors flow a gazillion gallins per minute or 3.91. Both injectors will adjust their pulse to maintain this air/fuel mixture over the vast majority of the stock 8 degree or 25 degree map.

It's a moot point anyhow since the factory 25 degree map's (file 141nx104) has the injector size set to 3.91 by default. SOmebody was obviously not comfortable tuning the closed loop system to the larger CVO injectors or this was a huge mistake.


I have a top drawer map for my '06 with 8 degree injectors and I 'aint changing it if it's not broken. My rig is running like a scalded dog, getting PLENTY of fuel and picked up horsepower and torque in all the right places. My bike was already making very good numbers with the stock download, love to dyno it again.