Engine stutters between 4k-5k RPM - Help Please

[CordovaJohn]

2004, R1150R, 72,000 miles, one owner, all service has been done at dealer on schedule. In 5th hold throttle wide open at 3,000 RPM and let it run up to 7,000 RM. It pulls ever increasingly hard except between 4,000 and 5,000 RPM wher it stumbles a couple of times. Have replaced fuel filter, had injectors cleaned, verified fuel pressure okay while riding, new plugs. Dealer is stumped. Any ideas would be appreicated. Thanks!

[Dr. Strangelove]

recently had a similar problem. I wouldn't say quite hesitation or stutter, but the engine was "reluctant" to run smoothly under hard throttle between 4500 and 6500.
It was the air filter.
It didn't "look" that dirty, but there was a lot of grit in it.

[towerworker]

You might consider checking the ignition "stick coils". My 04 had a similar issue and found one of the coils was bad. The "stick coils" are on the primary plugs (on the very end of the cylinder). The engine will continue to run on the secondary plugs even if the primary's are shot but it won't run well.

They're not cheap ($115 or so each) The replacement coils are redesigned to better handle the heat within the plug well. Heat seems to kill the original coils.

Wayne

[Dr. Strangelove]

You might consider checking the ignition "stick coils". My 04 had a similar issue and found one of the coils was bad. The "stick coils" are on the primary plugs (on the very end of the cylinder). The engine will continue to run on the secondary plugs even if the primary's are shot but it won't run well.

They're not cheap ($115 or so each) The replacement coils are redesigned to better handle the heat within the plug well. Heat seems to kill the original coils.

Wayne

Hey, Wayne and Happy Thanksgiving to all

How "unwell" does the engine run. With my "issue" I considered them as a culprit, but I was able to comfortably do a 3200 mile trek. At a shop in New Philadelphia, Ohio, the guys there said that it would rune "really really bad."

Hard to keep it going at idle? Smoke or gas fumes from exhaust? Very poor power? Do these things go out gradually or at once? Is it a subtle change at all or a black and white one?

Thanks

John

[boxermania]

John

The stick coils degrade gradually for the most part and then they just quit......most of the time the changes in operation are subtle. When replacing, do so in pairs and save you some aggravation down the road.

[CordovaJohn]

Has a good air filter. The stutter is not bad. If you wind up throuth the gears you really don't notice it since the RPMs don't really drop below 5,000. It is just that between 4,000 and 5,000 RPM in higher gears the acceleration falters maybe twice. If you run 3,000 to 6,500 it in lower gears you really dont notice it since it goes through that 4,000 to 5,000 range quickly. In 4th gear you can barely feel it. In 5th you feel it because that band last longer. Have not wanted to try it in 6th (too fast for me).

Occasionally during normal riding when you turn it on to pass someone it will sort of "backfire" a little through the intake.

I first noticed a problem riding home from the dealer after the 66,000 mile service. The left valve cover gasket around the primary plug was leaking oil and saturated the plug, coil and wire (it ran very, very bad then). Turned around and returned to the dealer where they fixed the leak and cleaned everything. It was much better after that, but the problem described above was there. Tried a different (but used) coil on the left plug without help. Over the next few thousand miles I used Techtron fuel system cleaner and it got some better. Then the dealer sent the injectors off for cleaning/testing, and supposedly all was okay. Was maybe slightly better after the cleaning, but the problem is still there.

It is possible the problem was there before the oil leak, and I just became sensitive to it after the leak (I cannot be positive either way).

The problem seems worse in warmer weather. Sometimes the problem will not appear for several turnons, then occur.

Thanks for your help.

[Dr. Strangelove]

a little followup in my case

Rode today and she seemed running fine, but I pulled the secondaries when I returned home. The left side made no difference, but the right side--wow--the engine couldn't stay lit. Time for new stick coils for Stella!

[jcridge]

You have a bad left side stick coil....

Replace both stick coils, all 4 spark plugs and sync the throttle bodies. At 72K miles, look at the high voltage leads to see if they need replacing.

I would also recommend running Seafoam for a while to help remove the carbon that has been building-up.

[CordovaJohn]

I replaced both stick coils and it ran great this last weekend. Rode about 150 miles both Sat and Sun. Was cold (high mid 40s) and before was better in cooler weather, so not positive yet how it will run in warmer weather. Will take a little while to see how it goes.

Thanks for all the help.