Mounting K1200RS throttle bodies on K1100.

  • Hello!


    There is a chance to buy in low price K1200RS throttle bodies. My question is: is there any benefit in such operation. Only TBs would be switched, original injectors and airbox is left. The engine has Motronic 2.2 ECU with no lambda sensor. What about throttle position sensor - is there a way to fit it?


    Best regards,

  • Quote from "Rafal"

    Hello!


    There is a chance to buy in low price K1200RS throttle bodies. My question is: is there any benefit in such operation. Only TBs would be switched, original injectors and airbox is left. The engine has Motronic 2.2 ECU with no lambda sensor. What about throttle position sensor - is there a way to fit it?


    Best regards,


    You mean this one? It's the same switch..


    More air = needs more fuel, saying higher fuel pressure..


    The benefit...dunno

    aus Norwegen, liebe grüße.

  • Quote from "RoyRogers"

    You mean this one? It's the same switch..


    More air = needs more fuel, saying higher fuel pressure..


    Hello!


    Thanks, now I can see that TPS is the same (it is not a switch ! ;) it is a resistance sensor ). Fuel ratio - that is a problem. Having lambda (o2) sensor, the ECU would increase dwell time, and problem solved. I my case: higher pressure, get new ECU and lambda, reprogram injection map or intercept some sensor, i.e. the engine temperature.


    BTW, the price for TBs is around 25 Euro with some plumbing elements.


    Best regards,

  • The bike will definitely make more power breathing through bigger holes. All of the 16 valve bikes, K-100, 1100 and 1200 use the same injector, so the only difference is mapping. Custom e-prom chip anyone? Or, try a Euro model K-1 ECM.
    You will loose the fast idle function however(the "choke" lever on the left swicht pod), as the K-1200 has an idle stabilizer valve with a cold start function that increases idle on cold start automatically and there is no way to adapt that feature to the K-1200 throttle rack. It may not be necessary however, as I'v ridden a bike, and early K-100 RS with a K-1100 block, an eary two valve K-100 head (wtf?), Euro spec 284 degree cams and this thing had K-1200 TB's on it and old Bosch L-Jetronic for the fuel injection system. Effen thing made about 115 horses and went like a scalded dog? Can you say power wheelies? Cold starting wasn't a problem, I just had to crack the throttle a touch on start. If you know what the head wants in terms of porting and how to cut the valve reliefs in the tops of the K-1100 pistons this makes the best flying brick engine out there. Smooth as a baby's butt, nice wide power band and, like a said, big horsepower, plus the old two valve head has a bunch more coolant in it so it runs cooler when you are on it hard. Throw in an early three row radiator for safety instead of the two row garbage the K-1100 comes with.
    Something else I have often pondered would be the effect on power to replace the mild stock K-1100 cams with the 284 degree cams that came in Euro spec K-10016V bikes. With K-1200 TB's that might be a real screamer too.
    I'd do it. I put K-1100 TB's on an early two valve K-100 and it woke the bike right up. It's a better change than any aftermarket exhaust. Nice intake honk above five grand too.


    Btw, my tech friend is building one of these K-1100 hermaphrodite things for me now. It'll have '85 K-RT bodywork, no ABS, early K-100 wiring harness, L-Jet, small battery and light weight K-10016V foot peg plates (but I'm doing this on a K-1100 frame and keeping the Paralever) so the whole thing will weigh in around 565 lbs fully fuled, meaning light, and look oh so innocent, heh, heh, heh. Once you've ridden a bike with that engine you have to have it.

  • Hello!


    I was waiting for you Themason :). Yep, the TB would cost around E25. Are the old airbox "spring pipes" will fit K1200 TB? The expensive part would be chip tuning of Motornic. I don't think tha K-1 ECU would be 1 to 1 swap. Motronic 2.1 and 2.2 has different pinout. The hot cams were used in K1, K100 16V and K1200 RS, so if I lucky I will find one. I have all ready mounted 3-core K100 radiator with bigger fan. Yet I have a feeling that thermostat keeps the engine a bit too cold.


    Best regards,

  • the 12 TB didn't have an idle srew! 12 is setting idle speed by stepper.
    I've build a pcb with a micro for setting idle speed (prototyping only) with little LCD. I can see the warm up phase with increased speed, the turns, the highest turn ever (10.500 :mrgreen: that's the point my engine interrupts ignition)
    Second: you have to increase gasoline pressure to approx. 2,8 to 3,0 bar


    BUT listen: in higher turns the engine is too lean! So do not hold fullspeed longer time... alway look at oil temp! that's very important.


    Mine is going to 10.500 rpm in 4th gear... going into 5th, you're in "red zone" of rpm meter... just still so :mrgreen::mrgreen::mrgreen:


    at last: you will have a high wear of many parts! just think about...


    best, Michael

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