I have a 2011 Road King, 96ci with a SE intake, Fat Cat 2 into 1 and a SEPST with dyno tune. From the day I picked the bike up I thought "Damn, this thing is too loud". The Fat Cat had a the Q baffle which is to say louvered/wrapped. You could shine a flashlight in the muffler and see the two head pipes come together.

After more than 10k miles I just couldn't take it anymore, I ordered a concentric baffle from D&D and installed it. The bike is quieter and in my opinion right where I want to be noise wise. There does seem to be a little difference in power delivery (where and how much) between the two baffles but I'm good with it. I was getting mid 40s mpg with F/A ratios in the 13s (when the bike was dyno tuned with listed set up). So I'm figuring that mileage is gonna drop some because I've effectively richened up the mixture.

So my questions are:

If I'm good with the decrease in power am I good without another dyno tune?

At what point does/would the bike become too rich?

If I do go back for another dyno tune; will it mitigate some of the power loss?

Can I have the original tune for the first baffle stored so I can go back between the two?

Thanks

 

I would guess a new tune would be your best bet. They should have no problem saving your current map for you. With that baffle change and retune it is possible you could actually gain some torque in the lower rpm range and give up a touch on the higher rpm HP which is a nice trade off to most riders.

Doug

 

Umm, its questionable whether it will run richer in closed loop, the O2 sensors and ECU should be able to adjust things OK there. The possible issue will be with open loop i.e. when you pour it on.

Currently the bike's VE tables (where flow is recorded) will be as per the open muffler. So it might now be applying a bit too much fuel. No more than before, so your MPG shouldn't change but not the best mix for performance.

Cheaper fix than another dynotune would be to get the software and leads for the SEPST, then run Smart tune. That will get your AFR back closer to optimal.

 

Thanks for the replies so far guys. I appreciate the insight.

Foxster I found your post on Smart Tune on a forum in the UK. Is this link what I need?
I have tuner32109-08C

http://www.kutterharleyonline.com/harley/32184-08A Cables

http://www.kutterharleyonline.com/harley/32111-13 Software

http://www.kutterharleyonline.com/harley/32101-10 Training DVD

If I get these is that all I need to accomplish the job??

 

You will need the software too: http://www.kutterharleyonline.com/harley/32111-13

Whoops, see you found that.

I'd probably not worry about the training DVD. I watched a bit of it at the dealers and it put me to sleep. A beginner's guide like mine that you found is enough to get you going. Maybe get the training DVD if you struggle.

 

Thanks Foxster. I'm "special" when it comes to learning. For 33 extra bucks it'll be like having two people trying to pound it in my head.

 

Your options depend a lot how the dyno tune was done. Some tuners do not bother tuning the VE tables but just set up the AFR/Lambda table. This means that one cyl may be lean and the other rich but in average the bike runs at, say, 13.2 AFR. And the tune is typically cheaper. If this is the case, another tune is your best option but if you are happy how the bike runs, I don't see a reason for a new tune, it just runs richer now.

If the tune is done properly by setting up the VE tables and you have the orange sepst dongle and cables and you have a lot of time in your hands, I'd buy the sepst sofware (latest version) and few properly done smart tune rounds should fix the VE tables.
Ask your tuner how he did the tune.

Foxster, not sure what you mean by closed loop - if the bike is dynoed and AFR is 13, I'd say it is fully in open loop.

 

Maybe. Chances are though that the final dyno sheet given to the customer was a WOT pull i.e. no closed loop.

 

I have the software and cables on order, should be here in a few days. I also got the DVD so I'll bone up on it and at least be able to look at what kind of tune I have. Right??

BTW
I appreciate the help fellas.

 

Right, but it is kind of hard to find out what you have now. iirc on the screen where you select and load the tuning file, there is a tab that says "from vci", it's easy to miss but that is where you download your current tune. Remeber to do that and save it before you do anything else