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1Back to top Go down    K100LT '91 - Misfiring on Mon Jun 24, 2013 7:11 am

fertilemind

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Hi All,
The saga of my LT continues. I had a local shop do the engine repair work and they assured me all was fine the had the bike on a dyno and ran it up to 5th all seemed to be fine.(later discovered they were running it without a load!)
After fixing the seat and body parts I got to ride it for the first time. It missed under load. I decided to look at the plugs: Agggggggggg two Bosch and 2 ngk all the wrong heat range. So off to supply and 4 new NGK D7EA (supposed to be equal to Bosch X5DC. Also noticed some cracking on the HT lead at cylinder 2 coil connection.
Calling around only to find no leads in the country and 10 days delivery and R2,200.00 for a set from BMW. (beyond my price range at the moment)
I decided to get a similar set of car leads just to test all.
So new plugs gaped to .65mm new leads on - START
AGgggggggggggggg : Misses worse than before like I crossed a set of leads. Verified that coil number to cylinder number all ok. Still missing.

What am I missing? excuse the pun.
Rob


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1991 BMW K100LT | 1989 Suzuki GSX-R 750 K Slingshot
"duo sunt meliora quam quattuor rotarum"
http://www.robcochrane.com
    

2Back to top Go down    Re: K100LT '91 - Misfiring on Mon Jun 24, 2013 7:49 am

charlie99

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measure all the leads and get a good feel for what that is all about ...
try something ...with leads connected to the coil ..measure from plugtop ...2 and 3 and see what measurement you get
then do the same with 1 and 4

you should get something like (coils should be 10 k ) plus the leads them selves so I would guess at 21,000 ohms from end to end ....
if not ...investigate why

don't forget that some of the car leads do not extend into the coil as much as the bmw leads

the realm engineering leads are well priced as a set

just a helpful piece of experiment you could try


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

3Back to top Go down    Re: K100LT '91 - Misfiring on Mon Jun 24, 2013 9:09 am

fertilemind

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Thank you. I will test them all later and report my findings.


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1991 BMW K100LT | 1989 Suzuki GSX-R 750 K Slingshot
"duo sunt meliora quam quattuor rotarum"
http://www.robcochrane.com
    

4Back to top Go down    Re: K100LT '91 - Misfiring on Mon Jun 24, 2013 9:58 am

RicK G

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Fertile can you describe what is happening in more detail I have a feeling that you may be having the same problem that me and Rabid are having and if it is then it's not electrical although it seems like it.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

5Back to top Go down    Re: K100LT '91 - Misfiring on Mon Jun 24, 2013 6:25 pm

Rabidchiwawa007

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Indeed. I just got went through my CO potentiometer and even pre-maturely ordered a new one. Did more tests and found that the CO pot is in good shape. I cleaned my injectors awhile back (2k miles?). I'm going to take them all out and shoot some cleaner through them again tomorrow to re-check since I've learned so much since then. I'll also be looking in to some stronger spark plugs. Will also check fuel pressure, which is supposed to be around 36 psi?

Straight off, I can tell you that balancing the TB air bypass screws helped quite a bit, but did not solve completely


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1991 BMW K100RS 16v with K1100LT fairing
    

6Back to top Go down    Throttle body air bypass on Mon Jun 24, 2013 7:32 pm

ibjman

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The bypass screws only effect the engine at low sppeds 1000 to 2000 rpm.....once the throttle butterflies are are open than that those balance screws have little no effect.

Your problem is most likely ignition related if it's a dead stuttering miss.

As for fuel injector cleaning.......If that is/were an issue, one might run a bottle of Chevron Techron through the fuel tank......with the recommended amount of fuel. It's ver very good injector cleaner.

Also, there's the possibility of faulty broken wires to injectors? I believe all 4 injectors fire at one time, not sinquentiallly.

    

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