K100RS running rich

[grant71]

hello everybody. I am new to this site. i live in Capetown and recently bought a 86 K100RS. BEAUTIFUL MACHINE BUT SHE  RUNS RICH.i approached the  local BMW dealership to be told that they do not have anybody that knows this model as it is too old.any advice please. thanks

[Scott_]

Well, not knowing how many miles are on the bike, you might think about having the fuel injectors cleaned. This would address any leakage issues with them.

Your fuel control system uses an air flow meter, and possibly air/engine temp sensors as well, for setting the fuel mixture. Any one of them could be causing a rich mixture.

Air filters are generally way over sized for these bikes, but that doesn't mean that there couldn't be some kind of obstruction in the filter box, shopping bag, critter nest, etc......

[Inge K.]

Welcome grant!

To add to Scott's info, I would suggest that you start with the water temp sensor
(and it's related wiring and connectors), if you got a bad connection (or sensor)
the L-jetronic would think that the engine is colder than it really is.....
as the temp rises the resistance goes down.

Measure the resistance between contact 10 and 13 at the L-jetronic connector,
and compare with the attached diagram. (measure with both cold and hot engine).

Inge K.

[grant71]

hi. thanks for your advice. ill take the bike to an electrician. bike has only done58000 kms. i forgot to mention that in 2nd gear eg. when i open throttle wide  she jerks and has a flat spot for a  few seconds then takes off. of course this makes overtaking hazardous. when i open throttle slowly none of this happens and she accelerates smoothly. I have added fuel injection cleaner. lets  see what happens in the next few days.here in SA  one  of the petrol brands is Caltex which contains Techron. I ve read about BG 44 K. Dont know whether its available here.

[Inge K.]

A malfunctioning fuel pressure regulator would also cause a fat mixture,
the FPR should open at 2.5 bar / 36 psi.

Inge K.
 

[grant71]

hello again and thanks for your replies. as i said im filling up with petrol which is  actually the Chevron brand containing Techron. ill do this for a few tankfulls and then look at  the serious side like electronics. my fuel consumption in and about the city is about 8.25 litres per 100 kms. now i also own a HONDA  shadow vt 1100 ace. this bike is 96 model with 13 k  kms. its fuel usage in town is about 5.86 per 100kms. i drive pretty slow in town. ( btw im nearly 72 ).  ive been reading the posts avidly and i must make this comment. if i lived in the States  id choose California . ive been to San Diego. spent some time with a friend in La Jolla. i absolutely loved the place. i really feel for you fellows who have to garage their bikes for the winter. months and months NO RIDE. Its like pining for a loved one.here in Capetown we can ride most of the year. the scenery is magnificent. in winter it rains a bit . no big deal. a little bit of a funny anecdote. i bought my K100rs from a retired submarine captain. SA only has 1 sub and the bloody thing does nt work. why i dont know. as you can well realize sub captains are meticulous people. hence my K is well looked after. the only problem the PO did nt ride it due to ill health. thanks for a great and informative site. im addicted. Y'ALL DRIVE SAFELY NOW

[grant71]

hi Inge. Further to your advice re fuel pressure regulator may be  faulty causing excessive fuel usage, i phoned a bmw mechanic who tells me  he knows K100 well. He agrees with your assessment. im taking bike to him Friday. Btw Norway is playing SA football tonight. earlier i saw quite  a few good looking blondes waving Norwegian flags. its only a friendly. im surprised at the interest shown. Go well. Grant