K11 Owners Group

[Beachcomber]

Hi Guys,

whilst finalising the K100 /1100 lead sets [ production begins 1st Feb ], a forum member asked me to find out about k75 leads as apparantly [ pro-rata ] OEM lead sets are even more expensive [ rip-off ] than 100/1100.

I came across various referrences to "air - gap" in the K75 leads and dire warnings against producing aftermarket sets. As I know nothing
[ effectively ] about such matters - I put it to the guy manufacturing the other sets - who does. here is his response - verbatim -


Dear Manfred,

Thank you for your e-mail.

Be assured, there is no 'air gap'. The leads on the bikes use the same technology as the BMW cars, as do VW, AUDI, etc. etc. because most of the lead sets are made by Beru.

The cable is copper cored and the boots have an internal 1kOhm resistor at the coil end and 5kOhm resistor. The resistor is made from a compressed carbon material. As I said before, identical to the car manufacturers. People may believe the resistor to be an 'air gap', but it isn't. It is there to suppress the EMP pulse (interference) by restricting the electrical flow.

This 'air gap' myth is donkeys years old. People use to attach a 'button' on old copper core cables to make the spark 'jump' across the gap. The theory is that the air gap acts like a capacitor and 'compresses' the spark, therefore making the spark burn duration shorter and more energy released in a shorter time at the sparkplug. I am sure in a laboratory and you are running at 10,000rpm it may have some slight effect on engine timing, but in the real world it is nonsense.

Hope this helps!


There we have it guys. I know there are many K1100 owners who like me cross over to the dark side with 100's and 75's. Hope this info. helps to dispel yet another urban myth.

TJ
_________________
Beachcomber '93 K1100RS / '93 K1100LT and several K100's

[bmwmick]

Beach,
Tell your buddy it's not a myth, it's on page 21 of the BMW LE Jetronic
Engine Management Course Manual.

"NOTE: The K75 spark plug wires incorporate a glass resistor to prevent high
voltage bleed over and cannot be tested for resistance."

It will measure as an Open circuit with any normal meter.

Mick
_________________
Mick McKinnon
KOG#175
'93 K1100LT, '96 R1100RT, '84 R100RS, 2010 Kawasaki C-14
Tucson, AZ

[Flying Duck]

_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[bmwmick]

OK Drake,
Since you have some of both, why not measure them? I've measured both K75 and K100/K1100 secondary wires.

Mick
_________________
Mick McKinnon
KOG#175
'93 K1100LT, '96 R1100RT, '84 R100RS, 2010 Kawasaki C-14
Tucson, AZ

[Flying Duck]

K75 leads read 0 ohms.

It seems odd they'd need to do that on K75s but not K100s. Perhaps it has something to do with the K75 not being a wasted spark system. That's the only difference I can think of between the ignition systems.
_________________
93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE

[Rafal]