2001 K1200LT Coil

[BABABeemer]

I’m trying to install a K1200 LT Coil in a 2003 R1150RT to make it a twin spark and was wondering if any K bike owners have a schematic that shows the input wires to the three pin coil? They are labeled 1,2,&3 on the coil?

[dirtrider]

11 hours ago, BABABeemer said:

I’m trying to install a K1200 LT Coil in a 2003 R1150RT to make it a twin spark and was wondering if any K bike owners have a schematic that shows the input wires to the three pin coil? They are labeled 1,2,&3 on the coil?

Morning BABABeemer

 

I do have a wire schematic but?

 

#2 is 12v ignition switch input (that powers both coil sides.  The # 1 # 3 return to the Motronic on different inputs, those are what the Motronic uses to trigger each coil side independently. It also shows wire to terminal #1 &  wire to terminal #3 between the coil & the Motronic are RFI shielded wires.

 

Unfortunately your single spark 2003 1150rt only has 1 coil driver so about your only choice there  is to have it drive both 1 & 3. That could overload your 2003 1150rt's single coil driver & possibly make it fail. At least that would be my worry anyhow. I haven't ever tried to use a K bike 4 output coil on a single spark R bike. 

[BABABeemer]

Good morning dirtrider,

Thanks for the information. This K bike coil is what San Jose BMW used to convert the early R1150s to twin spark before BMW came out with the stick coil system. I’ll have to check with them about what they did about the single coil driver. Perhaps this coil could be used on a twin spark machine for those who want to eliminate the stick coils?

[dirtrider]

4 hours ago, BABABeemer said:

Perhaps this coil could be used on a twin spark machine for those who want to eliminate the stick coils?

Evening BABABeemer

 

That is a possibility but it would need some research first. The 1150 twin spark used 3 coil drivers, one driver for lower-plug common coil & a separate driver for each upper stick coil. They do spark lost spark (every piston up) so conceivably one side upper coil driver could be used to drive the upper side of the K bike coil as long as the K bike coil doesn't have a significantly lower resistance than a single stick coil does.   

[BABABeemer]

Thanks for the info dirtrider.

I did some coil resistance checking and my stock 2003 1150 coil was 0 .4 ohms. The K1200 coil measured 0.5 ohms when checking each coil between terminals 1&2 and 2&3. When I jumped terminal’s 1&3 together and measured them and #2 , the resistance was 0.3ohms so that was the resistance the motronic would be dealing with on my 2003 1150 conversion. I measured a new stick coil and the resistance was 1.3 ohms. I suppose if one wanted to replace their stick coils with a K1200 coil, they would have to add a suitable resistor to the wire running to the dual spark motronic.

[dirtrider]

10 hours ago, BABABeemer said:

Thanks for the info dirtrider.

I did some coil resistance checking and my stock 2003 1150 coil was 0 .4 ohms. The K1200 coil measured 0.5 ohms when checking each coil between terminals 1&2 and 2&3. When I jumped terminal’s 1&3 together and measured them and #2 , the resistance was 0.3ohms so that was the resistance the motronic would be dealing with on my 2003 1150 conversion. I measured a new stick coil and the resistance was 1.3 ohms. I suppose if one wanted to replace their stick coils with a K1200 coil, they would have to add a suitable resistor to the wire running to the dual spark motronic.

Morning  BABABeemer

 

Your stock coil should be closer to .5 ohms (at least most I have measured  with a precision Fluke are).

 

In any case, assuming your delta is accurate .4 ohms vs .3 ohms),  then at a nominal 12.5 volts coil input  the OEM coil (@ .4 ohms) is loading the Motronic driver at 390.6 watts & your K bike coil (combined primaries  of .3 ohms ) is loading your Motronic driver at 520.8 watts.  

[BABABeemer]

11 hours ago, dirtrider said:

Morning  BABABeemer

 

Your stock coil should be closer to .5 ohms (at least most I have measured  with a precision Fluke are).

 

In any case, assuming your delta is accurate .4 ohms vs .3 ohms),  then at a nominal 12.5 volts coil input  the OEM coil (@ .4 ohms) is loading the Motronic driver at 390.6 watts & your K bike coil (combined primaries  of .3 ohms ) is loading your Motronic driver at 520.8 watts.  

Great! Quite a difference for such a small change in resistance!

thanks for the information.