Engine Studdering

[hinglby]

Hello captains,

I've read every post I can find on engine issues and still can't get the Rocket to run correctly. The ride has 77k miles and has run flawlessly since new. Nothing has been done to the bike and now it has a stumble from 1800 to 2500 rpm. This has bee going on for about 1000 miles. I'm stumped!

I've been running the tune boy 20227 tune for ever with 100% secondaries and +2% AF across the entire scope. Since the problem started I've checked or changed the following:
Crank sensor - found it was clean and checked three times
TPS - check and it was at .610v adjusted to .600v
Stepper - was at .730v and is now at .720v
Checked all vacuum lines - found no issues
Throttle bodies are in in synch - at idle reading #1 .471, #2 .465, #3 .471 and the all fluctuate from .465 to .475 while at idle
Spark plugs look good - changed twice to make sure
Sprayed starting fluid around the throttle bodies, intake plenum, vacuum lines, intake manifold while running to verify no vacuum leaks
All coil wires are secure and tight including spark plug wires and 12v to coil and ground.
Check with several different tunes, no difference.

I haven't a clue what else to check. There is a stumble/hesitation in any gear between 1800 and 2500 rpm and is the worse if I slam the throttle in that rpm range. Slow throttle movement is less noticeable, but still there.

I though it may be a restrictive fuel filter, but then it would be restricting all the time. Same with the fuel pump.

I have a new TPS on order and am thinking about replacing the secondary as well as the stepper motor. The only other thought is to replace the coils and spark plug wires.

Any thoughts?

Thanks in advance!

 

[Blastedbones]

77k & nothing done to the bike.. valve clearances?( bit of a long shot, but.....)

 

[hinglby]

My apologies.... nothing done except for all the maintenance requirements. It's weird, it was running perfect and all of a sudden it stutters. It acts like an old Carter or Holley carburetor when the throttle pump doesn't work.

 

[rob o]

I had a similar problem once and after checking the plug leads for continuity I found that the front coil in the steering neck did not have a good earth due to rust between the coil and the mount caused by the mounting bolt being too long , all I did was clean the faces up and shorten the bolt and it clamped up properly and has been fine ever since

worth checking

 

[warp9.9]

I had a similar problem once and after checking the plug leads for continuity I found that the front coil in the steering neck did not have a good earth due to rust between the coil and the mount caused by the mounting bolt being too long , all I did was clean the faces up and shorten the bolt and it clamped up properly and has been fine ever since

worth checking

Clean a re-crimp low tension leads to the coils while your at it. they get loose and cause a erratic spark.

 

[Battersea]

Clean a re-crimp low tension leads to the coils while your at it. they get loose and cause a erratic spark.

Thats exactly what I had, shudder felt worse when accelerating.

 

[hinglby]

This is great information... Thank you. I will pull the tank back off and check the grounds to the coils and verify the positive lead connections. I will probably change the fuel filter while I have the tank off. Not that I believe it's part of the problem but just as a precautionary measure (changed every 25k already).

I knew I'd get some great suggestions. Thanks again!