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  #1  
Old 19th October 2011
SNMbass SNMbass is offline
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Default Does Your EFI 1200 Do The Herky Jerk With Throttle Just Barely Cracked?

Does your bike do this too?

Conditions: Any gear, but for example, 2nd gear, about 2,000 rpm and holding (throttle just barely open)

Symptom: frequent but not cyclical "stumbles" - i.e. feels like fuel or ignition just cut off for a tenth of a second then came back on.

Get above about 2,200 rpm and it stops.

I've had this issue since new. 3 different dealers have said it's "normal" for EFI Sporties. I'm starting to believe it's true.

I've tried to tune it out using the SEPST with no luck. Ultimately gave in to dealers' suggestions to dyno-tune. Still does it. The guy who actually runs the dyno says can't get rid of it - it's the nature of the beast for EFI Sportsters, which seem to use less sophisticated programming than Big Twin EFI.
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  #2  
Old 19th October 2011
gchristopher9 gchristopher9 is offline
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My 07 1200C stumbles as well. Been tweaking my cobra module trying to get rid of it for months, but nothing has helped. Good luck..
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  #3  
Old 19th October 2011
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look into the dynojet powervision it fixed the problem you are talking about plus no need to go to dyno shop you have it right on your bike. you can tweak everything plus you can read and clear check engine or stored codes. well worth the money
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Last edited by SpaceAce; 19th October 2011 at 20:27.. Reason: kant spel
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  #4  
Old 19th October 2011
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Just an FYI, 2000rpm is lugging the engine and will cause "herky jerky". Get those rpm's up. A carbed (like mine) will do the same thing at a steady 2000rpm. It's not good for these motors. You're actually hurting the engine at constant 2000rpm.
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  #5  
Old 19th October 2011
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Quote:
Originally Posted by SpaceAce View Post
look into the dynojet powervision it fixed the problem you are talking about plus no need to go to dyno shop you have it right on your bike. you can tweak everything plus you can read and clear check engine or stored codes. well worth the money
Was just going to post the same thing..my bike no longer does it.....even down to about 1500 RPM its still steady
The dealer calling it normal just mean its normal for the EPA tune that the bikes come with..I'm surprised your dyno guy could not tune it out...

Quote:
Originally Posted by Starleak View Post
Just an FYI, 2000rpm is lugging the engine and will cause "herky jerky". Get those rpm's up. A carbed (like mine) will do the same thing at a steady 2000rpm. It's not good for these motors. You're actually hurting the engine at constant 2000rpm.
Yes, but if your in traffic in 1st gear and just barely moving, you have no choice but to run at that RPM.....sure you could fan the clutch, but with a proper running bike, you don't need to do that.

and at 2000 RPM your not lugging the engine unless your trying to quickly accelerate in the wrong gear ....my bike pulls just fine from 2000 RPM in 1st 2nd or 3rd gear ..4th or 5th and it will lug
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  #6  
Old 19th October 2011
lfvc77 lfvc77 is offline
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Mine does it too, lean fueling to pass emission tests, EPA and CE requirements.
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  #7  
Old 19th October 2011
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FWIW mine fine.
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  #8  
Old 19th October 2011
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Quote:
Originally Posted by SNMbass View Post
Does your bike do this too?

Conditions: Any gear, but for example, 2nd gear, about 2,000 rpm and holding (throttle just barely open)

Symptom: frequent but not cyclical "stumbles" - i.e. feels like fuel or ignition just cut off for a tenth of a second then came back on.

Get above about 2,200 rpm and it stops.

I've had this issue since new. 3 different dealers have said it's "normal" for EFI Sporties. I'm starting to believe it's true.

I've tried to tune it out using the SEPST with no luck. Ultimately gave in to dealers' suggestions to dyno-tune. Still does it. The guy who actually runs the dyno says can't get rid of it - it's the nature of the beast for EFI Sportsters, which seem to use less sophisticated programming than Big Twin EFI.

Symptom: frequent but not cyclical "stumbles" - i.e. feels like fuel or ignition just cut off for a tenth of a second then came back on.

See the "Stumble on Cold Start-up" sticky fourth from the bottom on the main page.

I've tried to tune it out using the SEPST with no luck. Ultimately gave in to dealers' suggestions to dyno-tune. Still does it. The guy who actually runs the dyno says can't get rid of it - it's the nature of the beast for EFI Sportsters, which seem to use less sophisticated programming than Big Twin EFI.[/QUOTE]

Big twins don't use a more sophisticated program, in fact it's basically the same with just a few more features. The stumble can be tuned out, mine was with a SERT.
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  #9  
Old 19th October 2011
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Teehaml Teehaml is offline
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No stumbles here...
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  #10  
Old 19th October 2011
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Default

It just needs tuning. The problem is you bought a tuner that needs a $25000 dyno and a guy that understands what he is looking at.

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