Is a better tune in order

[Biggzed]

Mike - First off let me thank you for the overwhelming amount of data you have made available on this site. Truly amazing.

I have a 99 Road King FI that I had a 95" kit installed on last summer. I have never felt like it was tuned as well as it could be. There are 3 main reasons for this.

1) A pretty significant torque dip on the dyno graph. Goes from appx 94 ft. lbs to 82 ft lbs between 2800 and 3500 rpm
2) "erratic" AFR line.
3) A stumble (spits back through the AC) at low rpm cruising (ie. 40-45mph in 4th gear), no tach - sorry

Here is my build:
KB Hyperutectic flat top pistons
BC Gerolamy TC1A heads
SS 510G cams *builder tells me this piston, head, cam combo should give 9.5:1 compression*
Adj push rods
SE A/C
Bassani Power Curve True Duals w/ Bassani touring mufflers
PCIII USB
87.1 HP / 94.1 TQ

Do I have a bad head, cam, exhaust combo? Could the stumble and dip be tuned out? Have you had success dealing with symptoms like this before? The peak numbers don't bother me too much. I would like to get rid of the dip and have a flat AFR if possible. It appears very lean in the low rpm range. Could this be the stumble I am feeling.

I live in the Portland area and could easily stop by your shop to review and discuss my dyno chart in person. I'm not sure if it is cool to post my dyno chart on your forum. The builders name is on it and I would not want you to feel obligated to critique another shops work on this type of forum. Could I e-mail it to you?

Thanks in advance.
Biggzed

[Biggzed]

Sorry Mike. Forgot to mention I also have the HD Stage 2 ECM download as well.

Thanks,
BZ

[Mike]

Thank You, I hope it's not too overwhelming! I assume your numbers are SAE, 4th gear! Yes, you can e-mail the chart to "mike.stegmann@teamlatus.com". I apprecriate your consideration for the other shop for we would feel the same.
Overall your combo looks pretty good and well matched. We like to see cams with a little more lift to take full advantage of the heads but with similar timing as the 510's, for the compression you are running. But cams are not part of the issues your describing. We have always been a little apprehensive about building up Magnetti-Merrelli EFI bikes due to similar issues. Our problem is some work great yet those that do not can be extremely difficult to correct (and we become hypersensitive to the problems). I hate throwing money at these things but us, and others, have found the Screaming Eagle MM throttle body and Race Tuner (now available for MM systems) is the cure most likely to succeed. I talk about some of the inherent problems with the stock t-body elsewhere on this forum and how the SE unit corrects some of these. To use with the PC USB you'll need to recalibrate the ECM because it uses a different type of injector, along with a custom map and this would be a good way to go (good news is the USB version allows seperate front and rear cylinder tuning).
With reference to the torque dip, we find that the Bassanni Power Curves start to dip as we add overlap to cam timing, examples are on this forum. The RPM's for your dip though seem high, normally it's from 2200-2700 rpm (ignition timing may be playing a part here). Tuning can minimize this but it's still predominately a function of the pipe/cam combo. In summary, I would recommend the SE t-body, appropriate calibration and a PC USB custom map.
Thanks for using our forum, Mike

[Biggzed]

The information on your site is overwhelming in a very good way. Thanks.

The numbers I gave you are SAE. I am 99% certain it is a 4th gear run, although the chart doesn't show for sure. Once you see who did the tune, you will probable know better than I. He made 1 5th gear pass, but I don't think this is the chart for that run. Overall about 20 runs were made that day.

I sent you an e-mail with the chart. Once you have a chance to review, I would really like to know if you feel you could do better (in terms of getting rid of the stumble) with the existing set-up. I would especially like your input on the current AFR reading and if that is contributing to the low rpm stumble I have.

Thanks again,
BZ

[Mike]

Got it, you'll find a reply there. We've got some options.
Thanks, Mike

[Biggzed]

Thanks Mike. You can disregard the other note I sent back to you. I'll just call the shop as they were general questions.

BZ