Does this rough running only happen at idle?
If so, maybe it's EITMS ( Engine Idle Temperature Management System) shutting down the rear cylinder

 

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" Engine doesn't feel as crisp as normal and kinda feels like I'm pulling a trailer or there is drag somewhere. "

If you really want to fix the above issue (" HEAT & EITMS MAKING IT LDE LIKE CRAP ON HOT DAYS ") once & for all like i did with the results to back it up l then proceed below.

Adn NO its not all in yor head that your air cooled hd runs like crap on hot days loosing a lot of pwr & trq along with also having mushy less responsive throttle response,lower oil pressure,nosier valves,detonation,heat roasting you off the bike,etc all due to excessive the heat generated by HD's air cooled v-twin that's even worse in summer heat!

But 1st things 1st, you need to install and external crankcase breather system (if you havent already done so) like DKCustoms offers to remove the hot oil soaked crankcase gases & blowby from entering the intake being ingested by the motor.

That results in over enough miles more then normal / excessive carbon buildup in combustion chambers (on pistons & valves) which can increase compression a bit along with the excessive carbon buildup in comb chambers actually glowing red hot during comb process both of which make the motor much more likely to detonate esp in summer heat.

It can also foul the airfilter with oil prematurely clogging it reducing engine perf/pwr/trq in the process too,so get an external crankcase breather ASAP if you dont already have one.

Ok,moving on here.

All air cooled HD's loose significant pwr & trq along with making throttle response mush & less crisp/responsive too all due to excessive heat which unfortunately is normal & not something plugs.wires or egenral tune up fixes.

My 09 HD USED to do the same think in warmer summer heat just you you describe which i fixed once and for all when i installed 2 cooling mods at the same time that collectively together reduced oil temp 50+ deg f in summer heat.

The 2 cooling mods i installed were an ultracool oil cooler with dual elec cooling fans for cooling the oil (cooling oil also cools motor too) along with wards dual elec cooling fans too that target cooling heads & upper cyls that cooled oil 50+ deg in summer heat.

That resulted in the following improvements right off the bat :

* REDUCED OIL TEMP 50DEG POST INSTALLING THE 2 COOLING MODS.

* IMPROVED OIL PRESSURE IN SUMMER HEAT FROM 8PSI @ IDLE & 32-35PSI @ CRUISE PRIOR TO INSTALLING THE 2 COOLING MODS TO NOW 18PSI @ IDLE & 45-47PSI @ CRUISE POST INSTALLING THE 2 COOLING MODS..

* MOTOR STOPPED DETONATING POST TO INSTALLING THE 2 COOLING MODS..

* VALVETRAIN NOW REMAINS QUIET POST INSTALLING THE 2 COOLING MODS.

* MOTOR NOW RETAINS MOST OF THE POWER PWR & TRQ IT USED TO LOOSE PRIOR TO INSTALLING THE 2 COOLING MODS.

* THROTTLE RESPONSE RETAINS THE CRISP & TRQ'Y FELLING IT USED TO LOOSE PRIOR TO INSTALLING THE 2 COOLING MODS.

* MOTOR HOT STARTS FASTER & EASIER LIKE POST FUELING UP VS WHEN MOTOR USED TO BE ALL HEAT SOAKED PRIOR TO INSTALLING THE 2 COOLING MODS.

* RIDING COMFORT HAS IMPROVED A BIT TOO DUE TO REDUCTION IN HEAT GIVEN OFF BY THE MOTOR.

BUT BE ADVISED,you will not get all the same benefits i stated above if you dont install both of those cooling mods at the same time so if you want to correct the issues your motors having when it gets hot in summer heat loosing sig pwr/trq and feeling soggy due to excessive heat do what i rec and your issues when hot will be fixed.

BTW,if your bike doesnt have an oil cooler or has a stock oil cooler without elec cooling fans make sure you get an oil cooler with elec cooling fans.

Thats because an oil cooler without elec cooling fans is just about useless when needed most like when for example being stopped @ traffic lights or when at slower road speeds due to little to no airflow thru the oil cooler without elec cooling fans rendering it ineffective when it's needed most.

So keep tat in mind when taking all this in.

and 1 more thing,you will find many guys that will say there is no benefit to cooling a lrg disp air cooler HD v-twin motor and that its just that guys with oil temp gages worry too much etc.

But the problem with that is they say that when they have never tried cooling their air cooled hd's using the 2 cooling mods i rec here so they are basically FULL OF BS & dont know what they are talking about when it comes to benefits obtained when redcing oil temp 50deg f in summer heat because they have never experienced it .

So keep that in mind too & ask the guys stating your bike wont benefit at or or not much from the cooling mods i rec installing like i did on my bike that reduced oil temp 50deg f if they had ever tried doing it using same 2 cooling mods i rec installing @ the same time on their ?

Again,just installing 1 of the 2 cooling mods i rec isnt going to reduce oil/engine temp as much so wont get same or as good as result like i stated above i got on my bike with the 2 cooling mods.

I go by facts & results and the fact is i installed the 2 cooling mods at the same time experiencing 1st hand all the improvements in engine perf and overall rider comfort i stated above vs all the guys that says it not needed ,their bike went 100k miles without it etc with never trying it to see & feel all the benefits i got with my 09 flhtcu w 96" TC motor .

Happy Motoring.

Scott