Hi All,
a question for those knowledgeable people here. I am in the process of going over the old K as it is not running very smooth, and needs some tlc anyway. I thought I might get the injectors cleaned and tested. As mentioned in other posts and on other sites the injector coil resistance is expected to be 14.5 ohms. I checked all mine and they are 17.5. Makes me wonder if I have the right injectors, maybe the previous owner changed then at some stage. It is an ex police LT circa 1991, so one of the last K100s I guess.
Would being out 3 ohms make a big difference in the operation of the engine. I wonder if this is why I always thought it was very rich at idle but become better at higher revs. I had a CO analyser up it once and that seemed to confirm it was rich at idle then leaned out a lot at high revs. I was told that was probably not normal but the guy did not know why(was not a bike shop btw, not really anyone here in Canberra that know the old Ks well).
I have also noticed it is a bit noisy in the tappets so I am guessing i'll need to get that sorted out as well. Would having valve clearances out cause it to idle rough and "hunt" around a bit. I can never seem to be able to get it to stay balanced with vacuum gauges.

One other question someone may know the answer to, with the fuel pressure regulator. Once the fuel rail is at pressure, 36psi I recall, how long does it retain that pressure once the engine has stopped. The Clymer manual states to relieve this pressure before undoing fuel lines. But mine has always had zero pressure even 60secs after stopping engine. Is there a way to test the pressure regulator?.

Regards

Robin

Canberra, Australia.

Hi Robin, you ask a few questions; I'll try to answer some.

I wouldn't worry about the coil resistance too much. A higher resistance would not result in a rich running bike, more the other way around.
Running rich at idle can be a result of the temperature sensor (cooling water) as that is an input for the amount of fuel being injected. Otherwise I would think of a badly adjusted Throttle Position Sensor.
Irregular running and 'not being able to get the vacuum gauges right' often has to do with air leakages from the crankcase breather hose or the rubber pieces under the butterfly valves.
In order to test the fuel pressure regulator you would need to slot in a gauge with a T-piece and see what the pressure does.

Hope that helps, cheers, Rene.

The resistance of the coil on the injector is 16 Ohms and I wouldn't worry about a difference of few Ohms.

Renez gave you some good leads about checking for air leakage.

If you are running rich on idle, you can modify the CO by altering the setup in the air flow meter.
There is a screw to adjust the amount of air going through the bypass when the engine runs on idle.
You have to remove a small plastic cap on the top of the air filter cannister and with an allen key you can modify the setup on the air flow meter.

The fuel pressure should remain in the rail longer than 60 seconds (on my bikes, it stays for at least 1/2 hour). The loss of pressure can be the result of a bad pressure regulator, OR an injector leaking. A leaky injector could also explain why you are running rich on idle (spark plugs back).

Some pictures of the fuel pressure test are posted on the FI testing page (bottom of the page) These pictures have been taken by Roys.

Bert