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2003 R1150RTP bottom plug ID?


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I have been enjoying my new 2003 R1150RTP for three weeks of daily commuting (55 miles each way, up I-280 from San Jose to San Francisco) and some nearby weekend shake-down trips, about 2K miles so far. I'm working my way through the Annual+12K checklist, just so I'm sure all the maintenance is up to date. So far I've replaced the driveline oils, brake pads, and battery, and I ran a power feed under the tank to a USB charger for my phone in the glove box.


My VIN indicates it was built in 12/2002, and I understand the factory twin-spark engines didn't start until the 2004 model year. My plug covers go all the way front-to-rear of the heads, not only half as on twin-spark engines. If that's the case, then what are these on the bottoms of my cylinders?




It looks like a traditional plug wire used with a traditional coil, not a coil-on-plug setup like the primary plug. Its wire travels alongside the primary plug wire. I haven't traced it to its source.


Has this bike maybe gotten a Dual Plug conversion? I'll check the VIN with SJBMW's records to see if they can tell me anything about it.


Any education gratefully accepted!

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Hi, Bob -


Using your vin I get this which indicates double ignition started in Dec 02. Looks like your bike was one of the first to get it.

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Looks like a plug to me, pull that boot off, and you shall see
Already pulled the boot. Yes, they look like plugs from the outside, but I haven't removed them to see what's on the inside. They might be pre-heaters or knock sensors or who knows what else... I can't see what NGK or Bosch part number they might be.
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Hmmm, you're right! That shows double ignition starting from 12/2002 so I guess it's plausible I could have an early example.


I'll pull the lower (what appears to be) plug. If it's one of the sort used for auxiliary plugs (BOSCH YR6LDE or NGK DCPR8EKC) I guess that will be conclusive.

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Double plug conversions kits were available to those who had surging problems on the very early single plug 1150s. The process involve machining the head and adding a different coil. The plug wires were the traditional type you'd find on older cars.


The spark plugs were also larger in size than the later lower dual plugs. They would be similar to the regular/main plugs in size.

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Evening Bob


Pop the valve cover plastic bars off & see IF your upper spark plugs have a stick coil or conventional high tension spark plug wire.


If the uppers have stick coils then your bike is an original twin spark.


If the upper plugs have conventional high tension spark plug wires then it is a conversion. (would then also have a 4 tower ign coil)


The lowers were always conventional spark plug wires even on the factory twin spark.

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Yes, it has coil-on-plug "stick" coils with equal gauge primary and secondary plug wires. From your description, this indicates a factory original twin spark, not a conversion by either factory re-work kit or dealer/aftermarket hacquery.


Yet, to confuse novices like me with its muddled taxonomy, it has the earlier single-spark style cylinder head covers and spark plug covers (even though it apparently has a double-plug head underneath), and a pre-2004 model year. This was apparently an early example and (in Darwinian terms) a transitional form.


That means, for my refresh work, I need to order secondary plugs too, and the correct wire set when that becomes necessary.


Thanks for the education!

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Hi Bob

The bike may have been over on its side and damaged the cover. The old single spark cover may have come up at the right price!

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Yes, it has coil-on-plug "stick" coils with equal gauge primary and secondary plug wires. From your description, this indicates a factory original twin spark, not a conversion by either factory re-work kit or dealer/aftermarket hacquery.


Morning Bob


Please explain the EQUAL gauge primary and secondary plug wires??? Are you saying it has conventional high tension upper spark plug wires & not 3 little (1mm) wires going to each upper coil. The rubber boot on the conventional plug wire can sort of look like a COP coil. (best way to tell is the stick coils have 3 small 1mm wires going to them & NOT a single large diameter insulated conventional plug wire.


Converting an 1150 single spark to a twin spark using upper stick coils would be a monumental task as the Motronic would have to be changed & the bikes wire harness changed (or rebuilt), etc.


The early 1150 can easily be converted to the later twin spark heads but use a 4 tower coil (all 4 using high tension plug wires) without lot of effort (some were done that way)


I have no idea if your bike came with early valve covers or not (my parts books doesn't show that as an option but some things are not always listed).


My guess is that (assuming your bike has real upper stick coils) the original twin spark valve cover or covers were damaged from a tip over & replacement single spark valve covers were cheaper or easier to find.

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