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2015 ULTRA
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37 Posts
Discussion Starter · #1 ·
hi all,
the 14 & 15 Limited have higher compression and bigger cam, that makes it idle rougher then normal. This is causing my bike to surge such as in a school zone, trying to maintain 15mph or 20 mph steady, the motor surges. or when I am stuck in a traffic jam,
and I am in 1st gear or 2nd gear trying to speed up and then slow down, while slowing down the bike bucks, surges, and I have to pull in the clutch or the tranny slop starts to bang loudly.

How can I de-tune my motor so that it runs great and smooth at lower rpms and slow speeds?
thx:nerd
 

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Just Ride
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3,732 Posts
Not de-tune, have it tuned/dynoed to perform at all rpms.
 
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12,940 Posts
Take it back under if under warranty. Cleaned my buddy's IAC valve and surging stopped in traffic.
 

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I have the same issue with my 14 limited. But it's not a surging problem. I think it's more of drive train slack in the primary to transmission to drive belt all having some slack. And then you bounce off the forward backward lunges. At slow speed ie 15 mph I keep in first gear and or pull in the clutch and coast then accelerate etc. When I got my 05 it did something similar till I adjusted the primary slack. The 14 is an auto adjuster. Not sure of the answer for the 14
 

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I had the same issue with my 15 SGS. I had done a stage 1 when I purchased the bike and the dealer did a remap. I had a lot of compression and was hard to drive at 25-35 mph. My dealer hired a new parts guy, he has been in service , does his own work races bikes etc. suggested I put on a tuner (non Harley part) and what a difference it has made. Much easier to ride at lower speeds and around town. Also seems to be much smoother at high speeds as well. Just turned 2K miles on it since I did it and have had no issues. Here is a link to what he suggested.

http://sales.nightrider.com/fl-af-xied-10.html
 

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2015 ULTRA
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37 Posts
Discussion Starter · #8 ·
Yes, I did this, I took it to the dealer and paid for SEPRT and paid for the dyno tune. I even asked for the tuner to make it run better at low RPM's and Low Speed. the tuner told me that this is a mechanical condition EX. the Compression and Bigger Cam, does not run good at slow speeds.
I wish I could go faster, I live is a Large 25MPH town, school zones, and the Traffic jams on the way home from work. I do not have a choice on the speed I have to drive.
My other choice is to not take the jerking, surging bike, or take the Gold wing that does not do that?
 

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2015 ULTRA
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37 Posts
Discussion Starter · #9 ·
YES!
this slop in the Tranny & Primary is quite noticeable.
and combined with the motor surging, it sounds like something is guna break.

mine has this slop in the drive train too!
I have the same issue with my 14 limited. But it's not a surging problem. I think it's more of drive train slack in the primary to transmission to drive belt all having some slack. And then you bounce off the forward backward lunges. At slow speed ie 15 mph I keep in first gear and or pull in the clutch and coast then accelerate etc. When I got my 05 it did something similar till I adjusted the primary slack. The 14 is an auto adjuster. Not sure of the answer for the 14
 

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With the type of problem you are having it might be worth the shop using the SEPST to smart tune it in the actual road conditions & environment you are riding in & having issues with.
It would only need a few samples and at worst it won't improve it, at best you'll be a happy customer.
 

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Do you have a tach? What rpm are you trying to hold? 25 in low should have plenty of rpm for a smooth driveline but throttle is extremely sensitive in first. Is that your problem? Either a very sensitive throttle OR driveline knocking in a higher gear? Some rpms are just too low for "floating" (not accelerating or slowing) with the clutch engaged. Accelerating a bit and coasting with the clutch in is fairly common at low speeds. This is a V twin, not a V 8 and it bucks at low rpm.
 

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2015 ULTRA
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37 Posts
Discussion Starter · #12 ·
thx for the tip.
That is what I did, I asked the tuner guy if there was anything else he could do, and he did try a second time, to tune it.
But, it still will start to surge at a STEADY slow speed in any gear,
and starts to buck on decal, when you are at 0% throttle slowing down.
thx for the advice. :smile
With the type of problem you are having it might be worth the shop using the SEPST to smart tune it in the actual road conditions & environment you are riding in & having issues with.
It would only need a few samples and at worst it won't improve it, at best you'll be a happy customer.
 

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2015 ULTRA
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37 Posts
Discussion Starter · #13 ·
yes, when ever you are holding a steady speed at 30MPH or less,
the motor surges.
Anything at 2000rpm or less.
the worst is on deceleration, 0% throttle, and you are coming to a stop or less than 15MPH,
the bike starts to buck, surge, in whatever gear, even 1st.

I think the motor 10:1 compression is to much for a touring motor.
The motor does not like to run at less than 2000rpm, unless it is under a load = accel.

:angel

Do you have a tach? What rpm are you trying to hold? 25 in low should have plenty of rpm for a smooth driveline but throttle is extremely sensitive in first. Is that your problem? Either a very sensitive throttle OR driveline knocking in a higher gear? Some rpms are just too low for "floating" (not accelerating or slowing) with the clutch engaged. Accelerating a bit and coasting with the clutch in is fairly common at low speeds. This is a V twin, not a V 8 and it bucks at low rpm.
 

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2015 ULTRA
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37 Posts
Discussion Starter · #14 ·
Another good example, is when I am caught in a traffic jam. the traffic comes to a stop. then you are in first gear, and you accell up to 10mph, hold it at 10mph, then back off the throttle slightly to slow to 5mph,
this is one of the scenarios where the bike's motor will surge.

another is you are in 4th gear coming into a town that has a 20 or 25 MPH speed limit, and you need to maintain a steady 20mph, the motor will surge a lot in 4th gear, and 3rd gear.
you almost have to drive around town in first gear with the motor over 3000rpm's just to drive through a town at 20mph.

and if you are in 3rd gear at 25, maintaining a steady 25mph, and you back off the throttle just slightly, the motor will buck, surge, and slap all the SLACK in the drive train so loud, my wife yells,
what is that noise???

I took a 2013 Limited for a test drive at the Dealership,
and this bike did NONE of that.
I could drive the 2013 Limited at 1000 rpm idle to 1500rpm accel or decal or steady, and it NEVER bucked or surged.
it is a 2014 Water Cooled problem,
that motor has to much Compression and cam to idle smoothly.
even the Tuner agreed with me.

he suggested buying a NON-water cooled motor.
. :|
 

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I have a 2014 Ultra too but have not had the issues you describe. I did add a fp3 controller as part of a stage 1 upgrade. Maybe that fixes some of the low end torque issues.

Also, I am a bigger guy so maybe my bike is under load more than yours.
 

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2015 ULTRA
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37 Posts
Discussion Starter · #16 ·
hi swift,

you are correct, an Ultra is Air Cooled, and has less compression
than a Limited.

Ultra = 9.7:1 comp.
Limited=10.1:1 comp.

That additional compression make s the motor Idle Roughly,
and Surge at low rpms.

NOT a good idea on a Touring bike.
I test drove an Ultra, and it ran fine!

I have a 2014 Ultra too but have not had the issues you describe. I did add a fp3 controller as part of a stage 1 upgrade. Maybe that fixes some of the low end torque issues.

Also, I am a bigger guy so maybe my bike is under load more than yours.
 

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2015 ULTRA
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37 Posts
Discussion Starter · #17 ·
hi swift,

you are correct, an Ultra is Air Cooled, and has less compression
than a Limited.

Ultra = 9.7:1 comp.
Limited=10.1:1 comp. AND a slightly bigger cam.

That additional compression make s the motor Idle Roughly,
and Surge at low rpms.

NOT a good idea on a Touring bike.
I test drove an Ultra, and it ran fine!

I have a 2014 Ultra too but have not had the issues you describe. I did add a fp3 controller as part of a stage 1 upgrade. Maybe that fixes some of the low end torque issues.

Also, I am a bigger guy so maybe my bike is under load more than yours.
 

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Registered
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635 Posts
hi swift,

you are correct, an Ultra is Air Cooled, and has less compression
than a Limited.

Ultra = 9.7:1 comp.
Limited=10.1:1 comp. AND a slightly bigger cam.

That additional compression make s the motor Idle Roughly,
and Surge at low rpms.

NOT a good idea on a Touring bike.
I test drove an Ultra, and it ran fine!
I have an Ultra Limited that is water cooled.
 

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2015 ULTRA
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37 Posts
Discussion Starter · #19 ·
I have an Ultra Limited that is water cooled.
OPPS, I see.

in 2014, HD does not call the Limited, an Ultra Limited.

You either have an Ultra, ( air cooled motor)
or
you call it a Limited, ( water cooled head motor)

the Ultra and the Limited are different bikes,
especially with the decision to WATER COOL the heads.
that is a BIG difference between an Ultra, and a Limited.

and I can tell the difference when I drive them. I do not like the higher compression.
it makes the motor more Throttle responsive to acceleration.
but, it also makes the motor idle rougher and run rough at low rpms.

thank you
 

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Hi Mike,
When I was mentioning to "smart tune" it, I was actually suggesting that they take the bike on the road , rather than back up on the dyno as the VCI box can be put into a "smart tune" mode that allows it to sample data as it is being ridden and offer suggested changes to the V.E. tables. This would allow the bike to literally be ridden in the problem area and may suggest relevant real world changes that might not be made on a dyno. Then when the bike is back at the shop after the ride these suggested changes can be uploaded onto your current map.
So long as they save the current dynode map that you have prior to making any changes then they can always go back to the original one you have.
Also, something else that might help. A table in your SEPST program that can make your throttle a lot more sharper is something called throttle progressivity. When the bike is stock the initial throttle openings are softened for want of a better description. Often when a SEPST map is installed it is common to adjust this table to make the throttle more responsive, particularly in the low percentage throttle range. It might be worth asking if it has been adjusted for maximum sharpness which considering your issue might not be beneficial to your daily riding situation.
Maybe a search on the forum might show what it is or a quick Google search for "Harley throttle progressivity" and "smart tuning" will explain it better than I ever could and will show links to where it has been discussed.

Good luck
 
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