Intermittent Stumble/Misfire under load, idle during time at rally

[bicyclenut]

Have a 2010 R1200RT with about 127,000 miles on it. Rode it down to Rally in Lebanon this past week and it seemed to be running a bit rough at highway speeds after riding about 250 miles from Chicago area to Indy, at first I thought maybe just road surface. Once down in area I noted that the idle was not as smooth as usual and starting was a bit rough, not as quick and definite as before on acceleration. When riding I found a pretty consistent misfire or stumble, mostly under load, required more throttle off the line and worse when hard acceleration or up grades. At cruising speeds, maybe 4000 RPM, you would notice a regular stumble/misfire. It pretty much did this for 2 days of riding about 500 miles around the area. On Saturday was caught in the isolated heavy rain around rally site and when riding back to hotel the bike miraculously ran like normal, pretty smooth for a bike with 125,000 miles. You would expect moisture to have the opposite effect, causing a misfire and ignition issue, etc.

For reference spark plugs were changed at 114,600, and coils were changed at 65,300 when I noticed a misfire/stumble at highway speeds, less frequent and a bit different than this as only noted at higher speeds in gears 4-5-6.

My first though was had to be a coil issue. I had coils in my cart at EME and ready to order before I rode back home so they would arrive this week. But after Saturday and the entire 500+ mile trip home Sunday, the bike was smooth and rode like normal, no misfire, no stumble.

Anyone else have something similar? Any suggestions or ideas? My gut feeling is to replace the coils and maybe just do the plugs at the same time even though a bit early as interval is 24K. Haven’t ridden it yet this week since returning from Lebanon.

 

[jandhumphreyme]

Moisture in the gas, or connector. If its running fine, don't mess with it.

 

[dennypink]

Loose battery cables?

 

[bicyclenut]

Back home rode it yesterday, still has intermittent miss or stumble at times, idle seems rough compared to past. I do not it has a backfire or popping sound on engine braking much more often that before. Probably going to pull plugs and take a look, maybe just replace coils as last ones didn't last this long and similar intermittent problem as when I did these last.

 

[omega man]

I would be interested to hear what it is.
On a Rotax engine- it was fouled spark plugs that didn’t look fouled……
On an 8.1L V8, it was spark plug wires……
Both engines exhibited the problem you described.
Good luck.
OM

 

[bicyclenut]

Replaced plugs and all coils. Also while apart replaced air filter (a bit dirty, but not bad), checked cables and vacuum lines and didn't find any issues, did a throttle body sync, maybe a slight adjustment but pretty close to even. Started and ran in garage and idle seems smoother and doesn't seem to miss but no load on engine yet, raising RPM's the engine seems smooth and no backfire when letting off that would occur before at times. Rode to work and no issues, passed a truck on back roads so under significant load to accelerate and go around and no issues. Seems like coils again cause this type of problem. Will see if continues to behave well over next few rides. Data from GS-911 at idle didn't see to show any issues.

 

[PGlaves]

I long for the good-old-days when the coils would outlast the rings or the valve seats.

 

[bicyclenut]

Well, this is my second set, first set replaced at about 60K, now second set at 127K, so it would seem the service life is about 60,000 miles for coils. At least they are more reasonable from EME (Euro Motoelectrics), $940 for a set from BMW, about 1/2 that aftermarket.