HarleyTechTalk

What exhaust mods if any? Any kind of tune in it?
When it started doing this, had any mods been done shortly before it started? Any work at all before it started? Or just bone stock, no work on anything, even as unrelated as brakes or clutch adjustment?

The surging you mentioned as an early symptom leans towards Temp sensor as well (little extra fuel added initially). Full-on fuel dump at speed from a bad temp sensor will definitely cause your bronco to buck. Giddy'up!

We know you said "electronics" were not your strong suit but it's easy to check the sensor. Pull it and with an (borrowed or cheap) Ohmmeter attached and set to lowest Ohms range, place sensor in hot to boiling water and watch the show - just the sensor not the connector. If sensor's Ohm reading moves slow and smooth (analog meters are better than digital for this type of test) and holds the maximum value then check wires at connector (on bike).

wikiHOW/simple ways to test a temperature sensor with a Multimeter

Let us know what you find.

My old Twin Cam occasionally does that, but it's carb'd, cammed, aftermarket ignition, ThunderHeader, etc., so not unusual. Sounds like a gunshot, just part of the fun!
Kind of unusual with efi. Maybe a way to capture the event with a Power vision or other tuner hooked up when it happens, looking for an unusual ignition or fueling event?

S&S states the MR103EZ are suitable up to 10.5:1, so you should be fine.
Looks like 112-113 TQ and mid 90s HP, your results "should" be slightly better, with your compression bump.

Here is a chart.

Here is another.

I have heard from several that my 05 ecm should work with the ACR's
I will get this harness 70623-08

Quote from: Adam76 on Yesterday at 04:22:01 PM

Quote from: sfmichael on Yesterday at 08:51:57 AMThat cam will make great power, I'm pretty sure you'll love it. At .585 lift you will be right at the safe limit for stock heads / valve springs. Have you considered having the heads freshened up while they are off?

This particular motor only has 15K miles on it and I'm wanting cams that will work best with stock heads, but I could probably stretch the budget to a simple valve job.

Are you recommending upgrading the springs? S&S say it's a "bolt in cam for 103".

Thanks

If a competition valve job is in the budget, then do it. A multiple angle valve job by a savvy cylinder head specialist will yield additional airflow over the stock cylinder heads at a relatively modest cost, adding more power. Some bowl work by a competent head porter will yield even more. keywords: savvy / competent
I would never claim to know more (or even half as much:) as S&S, so if they say it's a bolt-in, I say go for it. I've kept .580 lift as the safe limit on stock springs but we're basically splitting hairs with an additional .005 lift. If you've already purchased them I would proceed as planned. If not, I'd take a look at the CycleRama CR-575. But the MR103 is undoubtedly a really good cam and definitely makes my short list of cams for a lightly modded twin cam

If there is a ground stud up under the rear of the tank, check the fastener on the wire.  The 07 touring bikes were of the vintage that the fastener would come loose and cause intermittent issues.  Hoss's suggestion is a good one that the symptoms you mention closely match. A faulty engine temp sensor will add fuel and black smoke "may" appear when it is bucking..

Less than 30k. Checked plugs, wires, and battery. All connections have been checked. The only thing I can think of is, as you stated fuel filter, pump and or regulator. Was hoping I didn't have to though. Pump primes fine, can't hear a spray, but that doesn't always mean anything. Also took the dash off and checked the connectors there since I had changed the ignition switch about 2 yrs ago. 

Quote from: kd on Yesterday at 09:51:37 PM

Quote from: SixShooter14 on Yesterday at 09:35:42 PM

Quote from: kd on Yesterday at 09:22:49 PMFor the above reasons (if it were me) I would stay on track and go one step at a time.  If you just tear it down it'll be hard to inspect everything with any real certainty of finding the demon that has appeared. I am confident you will find the issue if you use good order in your approach.  Either way I expect you will find some mechanical fault other than the ignition timing.

Thanks. That is all pretty much what I was thinking as well. Will open the cam chest and pull the head off tomorrow.

If you remove the throttle body (or carb) before the manifold, try to observe the oil film in the manifold if there is any.  You may be able to see if the cam overlap is contaminating the length of the intake manifold bore and how bad the oil contamination is.  Once you get the head off, if your piston has any carbon on the top look for clean spots around circumference of the piston at the cylinder wall that will indicate engine oil bypassing the rings.

will do. I pulled the air cleaner off and there was no oil in the carb or filter, but I didn't specifically look down the throat.

Quote from: SixShooter14 on Yesterday at 09:35:42 PM

Quote from: kd on Yesterday at 09:22:49 PMFor the above reasons (if it were me) I would stay on track and go one step at a time.  If you just tear it down it'll be hard to inspect everything with any real certainty of finding the demon that has appeared. I am confident you will find the issue if you use good order in your approach.  Either way I expect you will find some mechanical fault other than the ignition timing.

Thanks. That is all pretty much what I was thinking as well. Will open the cam chest and pull the head off tomorrow.

If you remove the throttle body (or carb) before the manifold, try to observe the oil film in the manifold if there is any.  You may be able to see if the cam overlap is contaminating the length of the intake manifold bore and how bad the oil contamination is.  Once yo get the head off, if your piston has any carbon on the top look for clean spots around circumference of the piston at the cylinder wall that will indicate engine oil bypassing the rings.