Missing in the rain??

[cwhy]

Just took a 1wk ride up into Arkansas last week .. first long ride for wife and I. Got into some light rain
on one day and we were fine with rain gear but bike statrted to "miss" a bit. This was in 6th gear at about 55mph
and still was a bit rough even in 5th gear. I seemed like plug wires may be the culprit? Rain stopped /road dried a bit/ran smooth again.
Its a 2002 with 37k on it
and plug wires are original so far as I know. Long time rider but this is my first beemer and I have been slowly learning
their "quirks". Is it possible that the low jugs getting wet in the front (cold) but not on the back(normal temp) causes
this phenomenoh?? Any one ridden in a down pour without any issues? Is this normal?

thanks
c

[bergj1986]

If the engine is only missing when riding in the rain, that narrows down the problem to being electrical. There are a few ways to check for electrical shorts in the ignition system.

I would start by checking the spark plug wires, do you see any cracks or fraying in the wires? Next, I would check the caps that connect the spark plug wire to the top of the spark plug. Check for any cracks or breaks in the cap. If there is an issue with the insulation of the cap, electricity that should be going to the spark plug can be shorting out inside the cylinder head.

If all else fails, start the engine and spray the spark plug areas with a spray bottle filled with warm water. If the engine starts missing when you spray it near a certain component, that's your issue.

[bergj1986]

Also, to answer your questions, no, the temperature change in the front and rear of the cylinder heads would not cause this problem.

I rode in the rain for about 45 minutes on my way back from Biketoberfest today and had no issues with the engine missing.

[Jose]

I agree with other replies to this post. I rode over 500 miles down the west coast of France last July on route to Spain in freak weather conditions for the time of year. It rained and it rained and it rained some more. I crossed the Pyrenees by way of one of the highest metaled roads, over 5000 feet. On the return journey when approaching the Pyrenees the rain was so torrential it was running off the fields onto the roads turning them into shallow rivers. The bike (admittedly a twin spark 04, 20k miles) never faltered once. I've done the same 3000 mile journey on a 25 year old R65 and that was problem free as well. These bikes are designed to work in wet conditions, your problem is almost certainly electrical and can be resolved. I cannot offer any better advice than you have already received. I would however in your circumstances 'grasp the nettle' and immediately change the plugs and leads just to rule them out.

All the best.

[gregor]

I'd also check the notorious side stand interlock switch.
Rain has never bothered my BMW. I've ridden in continuous 3" standing water in a downpour in the Scottish Islands. That's when you find out how good the waterproofs are. Excellent bit inelegant ex- German Army Gore-Tex camo in my case.

[cwhy]

If the engine is only missing when riding in the rain, that narrows down the problem to being electrical. There are a few ways to check for electrical shorts in the ignition system.

I would start by checking the spark plug wires, do you see any cracks or fraying in the wires? Next, I would check the caps that connect the spark plug wire to the top of the spark plug. Check for any cracks or breaks in the cap. If there is an issue with the insulation of the cap, electricity that should be going to the spark plug can be shorting out inside the cylinder head.

If all else fails, start the engine and spray the spark plug areas with a spray bottle filled with warm water. If the engine starts missing when you spray it near a certain component, that's your issue.

Thanks for the advice everyone who replied, I like the spray bottle of water test idea......sometimes the simplest most obvious solutions are the best. Plus I will look at the kickstand kill switch-something I've toyed with disabling anyway!

[Jaeger]

I seem to have a similar problem with my 2003 R1150R. Runs fine except when wet. During a rain or after washing, it misses on the left side only. Pulling the plugs shows the left side blackened and the right one clean. The missing usually only happens when under load (i.e. accelerating). I've cleaned the plug and it runs fine, until the next time it gets wet.
cwhy, I'd be interested to know if you found the problem with yours.

[f4tweet]

Same problem I had on my 1973 Norton Interstate. I gave up on the Prince of Darkness.

[sweatmark]

Is it possible that the low jugs getting wet in the front (cold) but not on the back(normal temp) causes
this phenomenon?? Any one ridden in a down pour without any issues? Is this normal?

Living in the Pacific Northwest means riding in rain, mist, drizzle. Nine months out of the year. We've owned 4 BMW oilheads that worked fine in such weather, including a 2002 R1150R like yours.

As mentioned, electrical fault associated with moisture could be the issue, or maybe the airbox drain plugged up with something?

Just for the heck of it, pull off the cover and remove drain plug on the airbox to see if it's full of water, oil, mice.

[CycleRob]

A 2002 model's rubberized sparkplug wires and boots are over 9 years old and likely are age cracked enough for the spark energy to escape to ground. The most likely spot is where the wire is held close to the hot cylinderhead where it curves around the rear of the valve cover. That close contact and high heat takes it's toll on spark plug wire lifespan. I had those same cool wet engine misfires after washing my 2002 50R. Solved the problem, after finding out how ridiculously EXPEN$IVE the solid wires were, by spiral wrapping the wires in a quality brand electrical tape. Even tucked the starting endpoint underneath the cap rubber. The uniform 50% overlap of the tape wrap while spiraling it mostly to the other end was almost easy to do after both wires were liberated from their restraints and held tightly outstretched by my helper. A plastic ZIPtie around the tape termination point near the coil end prevents unraveling. I found out it was too subtle to be noticed as a shadetree modification by most people.

BTW, My wonderful F800ST has only 2 computer coils fed by low voltage primary wires with no high voltage secondary wires and they are in a very protected enclosed area high off the ground. The water cooled engine also thermally limits the external heat gain from the valve cover. Actually, there are a lot more reasons to put that bike on your new bike listing.