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K100-forum.com » Technical, repair and troubleshooting » Valves, spark plugs, idle speed e.t.c

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TIV

TIV
Silver member
Silver member
One thing that has been a wee bit annoying since I started using my K75RT in 2009, is that I have not being able to get the idle speed lower than 1300 RPM. If I slacken the adjusting screw until it´s loose, the idle speed will not go lower than 1300 RPM (hot). It has been like this since I got it. I would think that around 1000 RPM would be more like it. Otherwise the bike runs perfectly in my opinion. 

After I bought it I took everything apart, cleaned it, changed all rubbers in the fuel system, changed the rubber intake stubs and the rubber stubs between the throttle bodies and plenum. Put in refurbished injectors, new cables and everything that was not close to perfect. 


Now with close to 40.000 km on the clock the time has come to check the valves and adjust if needed, check spark plugs and adjust and lower the idle speed (using the correct screws of course). 


Do I need to check the timing? The bike runs perfectly, but for the fast idle speed, and the factory say´s leave it alone. Is there anything else that I am forgetting? How about the timing chain and the tensioner? What are the odds of this being worn or in need of attention after 40.000 km (and 22 years of course)? Anything else to bear in mind?


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1936 Harley Davidsson 750 (sold), 1964 BMW R69S (sold), 1973 Suzuki RM400 (sold), 1972 Triumph Bonneville (sold), 1971 BSA Thunderbolt (sold), 1972 BSA Lightning (sold), 1977 Yamaha XS650 (sold), 1971, BMW R75/5 (sold), 1973 BMW R75/6 (sold), 1984 BMW R100RT 1992 Yamaha FJ1200 ABS (sold), 1990 Harley Davidson Electra Glide (sold)
1990 BMW K75RT Ex-Police (owned now)
2004 BMW R1150RT iABS (owned now)

Cheers TIV
    

JGT

JGT
Platinum member
Platinum member
Do you have free play in the throttle cable outer and free play at the twist grip? John


__________________________________________________
1992 K75
    

TIV

TIV
Silver member
Silver member
Yes John, I do.


__________________________________________________
1936 Harley Davidsson 750 (sold), 1964 BMW R69S (sold), 1973 Suzuki RM400 (sold), 1972 Triumph Bonneville (sold), 1971 BSA Thunderbolt (sold), 1972 BSA Lightning (sold), 1977 Yamaha XS650 (sold), 1971, BMW R75/5 (sold), 1973 BMW R75/6 (sold), 1984 BMW R100RT 1992 Yamaha FJ1200 ABS (sold), 1990 Harley Davidson Electra Glide (sold)
1990 BMW K75RT Ex-Police (owned now)
2004 BMW R1150RT iABS (owned now)

Cheers TIV
    

Rick G

Rick G
admin
admin
Do your valve clearances first and don't pull the spark plugs out before you do them or carbon that is knocked loose from removing the plugs can lodge on the valve seat and give bad clearances on the exhaust valves.
After the valve clearances have been done you may find the idle settles down.
I had to rebuild the head on my K1100 a while ago and it's up to those tricks too now the valves have settled.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1999 K1100 LT with a Big Block 1200
    

duck

duck
Life time member
Life time member
One common cause of the idle being too high is that the TPS (throttle position switch/sensor) is not adjusted properly and is holding the throttle open too much at idle.

The spec idle is 950-1050 RPM but IMO 1100ish works better.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

ReneZ

ReneZ
Life time member
Life time member
Indeed, as above, look if the TPS is restricting further/full closure of the throttle plates. If that's not the case (and you don't have an air leak!) I would look at the bypass screws of the throttle bodies and close them all some. You'll want to keep the synchrionisation good whilst doing it.


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Greetings from Florida Australia! Having a 'new' K     Surprised-o: 

Rene


BMW K100 - 1985 (0030029) Scotland Valves, spark plugs, idle speed e.t.c Rain
BMW K1200GT - 2003 (ZK01223) Florida
BMW K1200GT - 2004 (ZK27240) Australia
    

TIV

TIV
Silver member
Silver member
ReneZ wrote:Indeed, as above, look if the TPS is restricting further/full closure of the throttle plates. If that's not the case (and you don't have an air leak!) I would look at the bypass screws of the throttle bodies and close them all some. You'll want to keep the synchrionisation good whilst doing it.
TPS is OK, I´ll have to close the bypass screws and sync the bodies.


__________________________________________________
1936 Harley Davidsson 750 (sold), 1964 BMW R69S (sold), 1973 Suzuki RM400 (sold), 1972 Triumph Bonneville (sold), 1971 BSA Thunderbolt (sold), 1972 BSA Lightning (sold), 1977 Yamaha XS650 (sold), 1971, BMW R75/5 (sold), 1973 BMW R75/6 (sold), 1984 BMW R100RT 1992 Yamaha FJ1200 ABS (sold), 1990 Harley Davidson Electra Glide (sold)
1990 BMW K75RT Ex-Police (owned now)
2004 BMW R1150RT iABS (owned now)

Cheers TIV
    

duck

duck
Life time member
Life time member
How do you know if the TPS is "OK?"  You need to loosen it and turn it counterclockwise (looking at it from the rear) to be sure that it's not holding the throttle open.  There isn't much play in it between it's stop and the click you hear when it's activated.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

TIV

TIV
Silver member
Silver member
duck wrote:How do you know if the TPS is "OK?"  You need to loosen it and turn it counterclockwise (looking at it from the rear) to be sure that it's not holding the throttle open.  There isn't much play in it between it's stop and the click you hear when it's activated.
To be sure I tested this with the Choke (fast idle) cable slack to be sure it wasn´t holding the throttle open. Then I adjusted the cable and the unit by the book (Haynes). 

When I juuuust start to turn the throttle I hear a audiable click from the TPS. There is also a small amount of slack in the throttle cable. So there is nothing holding the throttle open.


__________________________________________________
1936 Harley Davidsson 750 (sold), 1964 BMW R69S (sold), 1973 Suzuki RM400 (sold), 1972 Triumph Bonneville (sold), 1971 BSA Thunderbolt (sold), 1972 BSA Lightning (sold), 1977 Yamaha XS650 (sold), 1971, BMW R75/5 (sold), 1973 BMW R75/6 (sold), 1984 BMW R100RT 1992 Yamaha FJ1200 ABS (sold), 1990 Harley Davidson Electra Glide (sold)
1990 BMW K75RT Ex-Police (owned now)
2004 BMW R1150RT iABS (owned now)

Cheers TIV
    

duck

duck
Life time member
Life time member
If you didn't try re-positioning the TPS then you don't know if it's holding the throttle open or not.  It's a very simple task and worth trying.  If loosening the idle set screw didn't help then that is the first thing I'd do on a bike that's idling too fast.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

TIV

TIV
Silver member
Silver member
duck wrote:If you didn't try re-positioning the TPS then you don't know if it's holding the throttle open or not.  It's a very simple task and worth trying.  If loosening the idle set screw didn't help then that is the first thing I'd do on a bike that's idling too fast.
Thanks Frank, I understand. I´ll do what you suggest when I have checked/adjusted the valves and changed the spark plugs. If will probably also check and sync the throttle bodies, it´s a easy task when everything is apart anyways.



Last edited by TIV on Sat Oct 19, 2013 7:25 pm; edited 2 times in total


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1936 Harley Davidsson 750 (sold), 1964 BMW R69S (sold), 1973 Suzuki RM400 (sold), 1972 Triumph Bonneville (sold), 1971 BSA Thunderbolt (sold), 1972 BSA Lightning (sold), 1977 Yamaha XS650 (sold), 1971, BMW R75/5 (sold), 1973 BMW R75/6 (sold), 1984 BMW R100RT 1992 Yamaha FJ1200 ABS (sold), 1990 Harley Davidson Electra Glide (sold)
1990 BMW K75RT Ex-Police (owned now)
2004 BMW R1150RT iABS (owned now)

Cheers TIV
    

92KK 84WW Olaf

avatar
Life time member
Life time member
The idle speed on my LT was very high. I thought TPS too but the cause turned out to be a job done on the manifold by a PO, the worm drive clips/clamps were positioned so one of them was restricting the throttle returning to the rest position on the stop. Trouble was the position of the screw was not accessible.


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1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

TIV

TIV
Silver member
Silver member
I had the same trouble in 2009 when I renewed the intake stubs. Fortunately I discovered it before I put everything together. Very Happy


__________________________________________________
1936 Harley Davidsson 750 (sold), 1964 BMW R69S (sold), 1973 Suzuki RM400 (sold), 1972 Triumph Bonneville (sold), 1971 BSA Thunderbolt (sold), 1972 BSA Lightning (sold), 1977 Yamaha XS650 (sold), 1971, BMW R75/5 (sold), 1973 BMW R75/6 (sold), 1984 BMW R100RT 1992 Yamaha FJ1200 ABS (sold), 1990 Harley Davidson Electra Glide (sold)
1990 BMW K75RT Ex-Police (owned now)
2004 BMW R1150RT iABS (owned now)

Cheers TIV
    

stilbo

stilbo
active member
active member
Adjust TPS.

    

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