Stutter, misfire ?? at about 4000 rpm

[WaywardSon]

Not really sure what to call it, but the bike (96 R1100RT) has started to have some kind of misfire. It only seems to happen when in 5th gear, and is more pronounced under heavy throttle. I was riding yesterday, clear & dry as it has been for days. With easy acceleration the miss is barely noticeable, but the more gas you give it the worse it gets. Seems to start around 3700 rpm & continues until about 4200 rpm...after that the bike pulls fine until I run out of nerve or road.

 

I stopped and ran through the gears a few times full throttle & never could detect any miss until 5th gear, but it would do it almost every time in 5th. It only lasts a second or two and has never done it at higher rpms.

 

I always buy name brand fuel from stations that do a lot of business...but it doesn't "feel" fuel related to me. Could be wrong. Plugs have less than 1000 miles on them and are Autolite 3923's. Bike has about 55,000 mi. on the clock. Fuel filter is possibly original....as are the plug wires & the rest of the ignition system.

 

Your comments are appreciated......

[Linz]

When did the problem start?

[ShovelStrokeEd]

You may have answered your own question.

12 year old plug wires?

12 year old fuel filter?

[Jim Moore]

Also, make sure all your fuses and relays are pushed all the way in.

[WaywardSon]

I would say that in the last several months I have noticed the bike "skip a beat" maybe a half dozen times. As the problem did not repeat itself, I ignored it. However in the last few days it has become quite predictable. I can make it happen.

 

And yes, I may have answered my own question. I checked what service records I have & the dealers invoice for the 36K service makes no mention of a fuel filter. It is possible that it might be time to replace those

 

I will make sure that the relays/fuses are solidly in place. Thanks for the comments...great board!

[KMG_365]

I had a similar problem with "Maynard" and I know the fuel filter gets changed annually, but the plug wires are original. It happened when trying to hold a steady-state throttle at around 4000 . . . it would start to "miss" and stutter. I could accelerate through it, but riding two-up on a country road just puttering along it would get really aggravating. I also noticed it got worse when hot or when buying gas at some "other" stations in the back woods. Turns out KenH checked the OBD with his GS-911 and the Motronic had stored 82 "O2 sensor improbable readings" fault codes. He cleared them and by the time we got to Virginia checked again and the buffer was full again. I've since changed the O2 sensor (I guess at 140K miles I got my money's worth out of it) and the stuttering is gone now. SageRider was kind enough to clear Maynard's buffer again with his GS-911 at the UnRally in John Day, OR (I guess I'm going to have to cave and buy one of those). We then went for a 250 mile ride and checked again--no fault codes--so I guess that was indeed the source of my problem, but I wouldn't be able to tell for sure until I hit a gas station in the rain in "Middle of Nowhere", Arkansas with 90+ºF temps outside!

 

I think my mileage improved a slight bit as well. HTH