Some of you might remember that I took an 88" 2002 Fatboy up to a 95" last winter. Shortly after hitting my 1000-mile break in last August an interaction with a deer wiped out my chances of getting her on the dyno to see what kind of numbers it would make. Fast forward to this past weekend and I finally have the bike back together after fixing all the deer damage to it (and to me).

I live about 1.5 hours from a great machine shop that also happens to build racing motors for bikes and cars. They specialize in Harley racing motors and have their own drag racing team(s). As you enter the shop, you see nothing but lathes/mills/presses/etc. and various motors and parts everywhere around.




This specific drag bike just tested out at just under 250HP, has a custom fuel rail injection system and tons of computerization...




The dyno table was just getting cleaned off when I arrived. I left around 6:30am this morning for the 1.5 hour drive so we could start at 8:00.




Getting her on the table and ready for electronic surgery. She was clean when I loaded her, but making the drive through the PA rain and sludge took its toll. I started with a fuel map from one of the companies here on the forum that I'm sure was better than the stock HD configuration (which is what I used for the 1000-mile break-in), but it still needed tweaks in most cells - as expected. Too many variables with bike setups, pipes, environment, fuel injectors, etc. to have a cookie-cutter map work the same on various bikes.

 

A pic of her through the glass on the dyno. The tuner (Damon) isn't one of those "do a few full-throttle pulls" and call it done kinda guy. He let me spend the full three hours with him (yep - 3 hours) as he meticulously went through the rpm range and adjusted each cell on the map. It was cool to hear the bike stumbling a little at a particular rpm range, see him make some tweaks, and then hear the stumble completely disappear. Same thing with some decel pops - now you hear em...now you don't! The only time I stepped out of the booth during the tuning process was for the full-throttle pulls, just in case the bike decided to jump off the table or otherwise throw a tantrum.




Lots of attention to small details like warming the bike up, going smoothly through all the rpm ranges, letting her cool down before proceeding further, letting it warm back up, etc. Can't say enough about his knowledge and methodical process of the whole dyno tune.

When it came time for the full-throttle pulls, he established the baseline and then tweaked it through a series of pulls. The graph below is hard to read, but just seeing the difference between the lines shows the improvements that were made through his tuning process. Pay attention to the before and after fuel/air mixture at the bottom. He made sure he was nailing the dashed line target ratio:




The final pic shows the results, and I'm happy with them. I was hoping for mid 90s on both TQ and HP when I was building the motor. Taking out all the smoothing actually shows higher numbers, but I wanted to see the highest smoothing factor to kinda show me the "worst case" number (and probably a more accurate depiction of the performance). Ended up being 102TQ and 98HP, and I wasn't going to beat her up just to try to move that 98 number. (Besides, TQ is where it's at!) The flat spot is because of my choice to run an SE 2-1-2 exhaust with a PC5. If I had decided to use a good 2-1 exhaust and something like a TTS tuner, I'm betting that flat spot could have been erased. Again, check out the fuel/air ratio at the bottom - he nailed the dashed line target ratio almost everywhere...



Anyway, just wanted to post it up to show my specific build and results with a 95" motor. This shop (GMS) did a LOT of work to those 88" heads, specifically in the exhaust port. I won't go into those details as they are in another thread.

Hobo

 

Thanks for posting. Glad the bike and you are doing great.

 

That was a very nice tune.

 

They did a great job. I should have gave up some of my stubborn "I like these pipes" attitude and swapped over to a nice 2-1 before going today. That flat spot would be much, much smaller if there at all.

Oh well. Ride it a season and make more changes next winter. LOL!

 

greg @ GMS do the build?

 

He did my head work Kirby...I built it. He told me to tell you hello - I mentioned that you helped a lot of us here on the forum. If I had a 2:1 pipe laying around then my flat spot wouldn't be so prominent. I'll fix that over the winter...