BMW R1200R R1150R/T F800 K1200R R1100R/T R1250R RnineT Message Board

Pardon the elementary questions but this is my first opposed cylinder motorcycle and I am still trying to learn more and more about this monster.

Is a slow-turning starter normal for a R1100RT with 52K? It fires, and runs and rides like a dream. It's just this slow-turner makes me nervous. My K75 turns over much quicker, but neither as fast as my Honda's. I've used a Yuasa battery tender to top off the battery (using the auxiliary power plug on the side) but it took much much longer than usual vs the K75.

In talking with the BMW service guy today, I conclude my battery is weak and not putting out enough juice to spin the starter as fast as I think it should. The battery voltage after charging to 14.4 V has settled in around 12.4 V. Voltage may be non-linear, I don't know. I'll continue checking the voltage before ordering a new battery. When running, the alternator is feeding 13.8 V to the battery at a fast idle. Again, I'd like to see that number higher. I'm thinking the battery is weak and will not hold a full charge.

WhiteDog,

To fully charge a wet cell battery you need to sustain a 14.7V sustained voltage level charging current until the charging current drops off to near zero, indicating the battery is fully charged. That could be anywhere from a few minutes to 20+ hours, depending on the depth of battery discharge. Only then will the "at rest" voltage a day later be an accurate representation of charge. That 14.7V charging voltage requirement means riding the bike (or driving your car/truck) for any amount of time (typically electronically regulated at 14.1V) CANNOT FULLY charge the battery! The easiest way to do a proper charging is to get a Battery Tender brand charger. I have 1.25 Amp model that year round since new on Oct 2009 migrates between my truck, F800ST and now new riding mower's batteries. FYI, the `98 Pickup truck logs the vast majority of the summer and winter charger's electricity usage time. The charger: https://www.amazon.com/Deltran-Battery- ... B00068XCQU

A noticeably slower turning starter is most likely caused by 2 possibles. A battery that is near the end of its life -or- a starter armature that has worn down so much that conductive wear particles are clogging the critical empty space between the armature coil contact segments. There are other worn conductive particle locations inside the starter where internal shorts will dramatically decrease starter motor cranking speed. One website that I found has a good tutorial on Ohmmeter testing and cleaning starter motor internals. http://www.dansmc.com/electric_starters.htm Five screen pages down on that website is where cleaning/testing begins, but read the whole article. Be aware that a worn 20 year old starter can speed up the demise of a good battery, so I would plan on:
1--Properly fully charging the battery.
2--Removing, disassembling and cleaning/lubing the 20 year old starter internal parts before going the new battery route.