K75S Fan Stays On and on....

[Martin]

 :2thumbup: Keep on forgetting about the weather.
Thanks Martin.

[moto949]

     I finally got around to tuning the injection (as I drift further off the original post topic of the ever-running fan, sorry) and the bike is running real well. Some notes though; The 5mm hex airbox plug adjustment made virtually no difference to idle speed either before or after the injection sync (Motion Pro non-mercury Sync Pro). I turned the adjuster from full-in to 6 turns out, and the idle remained static, then it dropped a tiny bit, but ran a little rough, at about 7 turns. Anyway, when pressing the starter button now after a full warm up, the idle rises by about 50 (fifty) RPM, so I guess it's right on - I left the hex at 3 1/2 turns out.

    The current idle is at 1200 RPM (which I'm not unhappy with) but if I reach down at a stop light and press on the adjustment screw (between the 1st and 2nd brass screws) I can drop the RPM to 1000, since the screw rests above the stop with a gap of a couple mil (that screw is fully backed out now). BTW the TPS clicks just off the stop as it's supposed to, and there is a tad of play at the throttle grip, like the manual says.

     Overall the bike is certainly quicker than it was. Okay, it wasn't running great then but I never thought it was too bad for a non sport bike. I'd go so far to say that it's faster now, even with the taller 2.81 gearing I swapped in when I had the splines lubed just days before this injection retuning / injector upgrade. The motor has good response at all RPMs and no hiccups anywhere, and no backfire popping. I didn't yet advance the ignition, as suggested, (thanks guys) but I may try that some day.

     The bike is also smoother than before; I know this because right after I got the bike, the first mod I made was replacing the Mickey Mouse ear BMW mirrors with a set of Ducati Monster mirrors that actually showed more than my shoulders. Problem was, the new rear image was fuzzy, probably because the Ducati mirrors were plastic and lighter. I didn't really want to give them up because I liked the way they looked, and believe it or not, they cut turbulence that I could really detect (I rode around with one new one and one OEM for a couple days and noticed the difference side to side). But now, after tuning, there's no buzziness in the images at all.

      And... the fan still kicks on and off perfectly. Thanks again everyone!

[TimTyler]

Sounds like it might be dialed-in nicely.

Curious exactly which mirrors you're using.

[rbm]

The current idle is at 1200 RPM (which I'm not unhappy with) but if I reach down at a stop light and press on the adjustment screw (between the 1st and 2nd brass screws) I can drop the RPM to 1000, since the screw rests above the stop with a gap of a couple mil (that screw is fully backed out now). BTW the TPS clicks just off the stop as it's supposed to, and there is a tad of play at the throttle grip, like the manual says.

1200 is a bit high.  Sounds like the TPS is interfering with the TB given this description above.  I'd experiment by completely slackening off the screws holding the TPS to see if the TB returns to its proper resting position and the idle drops to 1000.  If successful, then try setting the TPS up but making very sure that you are not applying any side pressure that could cause binding.  If unsuccessful in dropping the idle, then that's OK also if you're happy.

[moto949]

Thanks RBM, I'll try it soon as I get a chance.

Re mirrors: They were off a Ducati Monster 796, but that type is probably mounted on other Ducs, too.  Wish I could attach a photo but my phone won't sync my latest shots and Verizon is working on a fix. I'll keep trying.

Please note that the mounting of OEM BMW mirrors is simple because of the threaded nut/bolt, but for the Ducati items I had to not only search through the many nut/bolt drawers of NAPA to find what fit as snugly as possible, I had to save some extra length for a few washers/spacers or my inner knuckles would brush up against the lower mirror stalk when shifting/braking. *I can't remember, but I may have also squirted a dab of silicone around the threads within the hollow mirror bolt housing to help quell any vibration I figured might occur. As I said, with the bike tuned and smooth, it's crystal clear, and I didn't have to tap any threads.

Beware that these mirrors are low slung. If I compare them to the bar ends on my old Guzzi Mille, I'd say the glass area is roughly in the same location, that is, the center point of the glass is approx 5 inches up at a low, 40 degree angle from either pinkie finger. The glass is also about 2 inches forward of said fingers, more or less in the same plane as the brake/clutch levers. So, like on my Guzzi, I have to dip my eyes down just a bit, but then again I do have an almost 100% clear view behind me now. At first I thought I made a mistake because of having to be looking further away and down, but I got used to it quickly and it's natural now -- it's just that the totally different location of the mirrors takes time to get used to. The OEM mirrors were 90% blocked when I wore my jacket (always), so cars sometimes seemed to come out of nowhere, and unless I consciously shifted my body over I couldn't see what was going on back there - (I'm 6'2" 225+)  Anyway for me, the new mirrors are safer because my eyes always catch movement back there.

Not that I'm unhappy with them at all, but... I recall seeing a Triumph Street Triple (not sure what year) with cool looking mirrors with maybe longer stalks that rose a little higher. No clue if they'd fit our bikes. Remember, it's important to look closely study the handlebar angle of the donor bike vs your model K75.

[TimTyler]

Thanks. I see how those stick out further than my "short" OEM Mickey Mouse mirrors.

[pugsley]

"When I recently upgraded to the 4-hole injectors, it whacked my air-fuel mixture"


I'm really glad I just read this. I just changed my 86 K75S injectors to the Bosch 4 hole green type. The bike runs better, much smoother and better pick-up but the idle is way too high at 1500-1600 rpm when properly warmed up. I tried to balance the throttle bodies using a Carbtune. I couldnt get #3 balanced close to #1 and #2 and I noticed that the FPR vacuum take-off hose on #3 was old and knackered so replaced it. That did it and I balanced them OK and adjusted the idle back to 1100 rpm. I followed the forum advice to set cylinder #1 to 1.5 turns out then balance #2 and #3 to that. I guess I need to start with #1 set to 0.5 turns out and balance the others to that?

That was about 300 miles ago and yesterday when I was out for a long ride I noticed the idle was back high again when properly warm.  I just had a good look at the crankcase breather hose for cracks but that looks pretty decent, I tried the propane checks on the injectors - nothing, I can see that the idle adjustment screw is not resting on the base plate but can be pushed down a bit then comes back again, I checked the TPS wasnt holding it off - nothing there, and now I was just starting to wonder if the new 4 hole injectors may have affected the fuel-air mixture and thought I'd consult the Motobrick oracle for some guidance. Time to get back out in the garage.....CO setting and then rebalance throttle bodies to #1 set 0.5 turns out. Anyone got any other ideas?

[The Mighty Gryphon]

I can see that the idle adjustment screw is not resting on the base plate but can be pushed down a bit then comes back again, I checked the TPS wasnt holding it off - nothing there

Do you mean the throttle stop screw?

Something is holding the throttle open.  Check the action at the grip, the cable and the operation of the "choke" controls.  Once you get the throttle closing properly, you will need to go back and rebalance the throttle bodies.  But this time leave #1 open 1.5 turns.  .5 turns is too rich, especially if those 4 hole injectors do indeed put more fuel into the mixture.

[Laitch]

The bike runs better, much smoother and better pick-up but the idle is way too high at 1500-1600 rpm when properly warmed up.

Would a good strategy then be to do the tuning procedure when the bike is "properly warmed up" to the extent that it was when the idle was too high?

[TimTyler]

Once it's warmed up and idling, press the green start button for a couple of seconds and see if the RPM's increase a little.

[pugsley]

Do you mean the throttle stop screw?

Something is holding the throttle open.  Check the action at the grip, the cable and the operation of the "choke" controls.  Once you get the throttle closing properly, you will need to go back and rebalance the throttle bodies.  But this time leave #1 open 1.5 turns.  .5 turns is too rich, especially if those 4 hole injectors do indeed put more fuel into the mixture.

Yes the throttle stop screw.

I checked all the usual things that may be preventing it returning to seat on the plate: throttle cable free play, fast idle (choke) free play, throttle position sensor. None of those are preventing it seating. Not much finger pressure is required to seat it so it feels more like the return springs are not strong enough and the butterflies are not seating fully.

I followed Tim T's advice. When I pressed the green starter button when engine is well warmed up (fan coming on and off) and the revs fell almost to the point where the engine died (as Tim described above) so I tried to adjust the mixture using the air flow meter mixture screw. It was originally set at 2 & 2/3rds turns out from fully seated. It was not possible to use the CO lean drop method because the idle still remains too fast (1600 rpm),even when resetting it by rebalancing the throttle bodies, however despite this and suspecting that the fast idle may relate to the idle mixture I set the mixture screw somewhere about 5.5 - 6 turns fully out and now it increases revs slightly when the green start button is pressed. The fast idle problem remains and I am not particularly happy to run the bike without knowing the mixture is not well sorted (having spent a lifetime running two strokes).

The fast idle is stopping me going further for now. But from what Moto 949 said he seems to have partially sorted this, and his problem sounds pretty similar to mine just not so bad. The strange thing is that the fast idle problem only really appeared after the upgraded Bosch green 4 hole injectors were fitted so I may pull these and check the o-rings and seating, although I expected that the propane check would have shown up any leaks there. If I can sort the fast idle I can then try to set the mixture with more confidence. Any thoughts would be welcome.

[TimTyler]

Now that the AFM adjustment is better, what happens to engine RPM's if you screw the three brass idle adjustment screws in all the way?

Have you ever cleaned those brass idle adjustment screws? Take them out, clean with carb cleaner, check the tiny O-rings, put a drop of clean motor oil on the O-rings, clean out the three holes in the throttle bodies, and then put the idle adjustment screws back in gently.

[pugsley]

When I screw in the brass throttle body air bypass balance screws right in the engine speed drops but does not quite stall. Whilst that helps with the idle speed the trouble is the throttle body vacuum balance goes out of whack especially on #3. I suspected at the start that these screws might be the cause of air leakage, so I did remove them clean them and used a cotton bud to clean the holes and the screw seats. I did this before I tried anything else on the air leaks check. I am now re-checking all the stuff I initially did. Today I replaced the air screws with some newer second hand ones from a set of K1100 throttle bodies. The O-rings were much springier on these ones and offered some better resistance when screwed in so I felt they were sealing better. However the end result was the same as before. So I can have lower sensible idle speed, brass air bypass screws screwed right in but with throttle body balance way off OR I can have excellent throttle body balance but very high idle speed (>1600 RPM).

I was planning on changing the original throttle bodies for the K1100 ones (using 3 of the 4) but I dont really want to go any further until I sort out the idle speed and the air-fuel mixture. It was cold out in the garage today so after about 6 hours of this I was falling into Zen's 'gumption' trap. I've walked away for now for some beer and thinking time.

[TimTyler]

I know you said the TPS or throttle cable aren't keeping the throttle open but if I were you I'd remove the TPS from the throttle bodies. Two screws and it slides right off.  I'd also disconnect the throttle cable from throttle bodies if removing the TPS doesn't lower the idle.

With a Carbtune attached I'd screw in the brass screws 98% of the way (not tight) and see where that puts your RPM's. That should get you under 1k RPM. If it does, look at the Carbtune and unscrew the brass idle screws to raise the RPM's to 1100 RPM. Don't worry about favoring any particular cylinder. Only unscrew the screws necessary to balance at 1100 RPM.

Those screws only affect the idle mixture. Once you open the throttle the air those screws leak becomes irrelevant.

Lift and hold the throttle lever on the throttle bodies and increase the RPM's to 3k. Do the cylinders looks close on the Carbtune?

[pugsley]

Thanks for the second pair of eyes. I agree it would be sensible to eliminate the TPS and throttle cable by disconnection, that way it is 100% certain there is no interference with the idle speed.

I'll follow your advice when I next get out in the garage and let you know the results.

[pugsley]

OK here is the final installment of this saga..

I decided that I needed to re-check again for air leaks. I had previously used propane around the obvious leak points but I was sceptical about how effective it was. I managed to borrow an exhaust gas analyser and decided to repeat the leak checks with propane and looking at the effect on the exhaust gas CO measurement instead of any speed increase. It clearly showed up a couple of leaks around the new injectors. I removed the injectors, cleaned the ports where they seated and used O-ring grease to reinstall the injectors. I restarted the engine, no excessively fast idle and no problem getting balance on all the throttle bodies with the Carbtune. I then set up the idle mixture at 2% CO. I have done a couple of hundred miles on it since and it runs like magic, certainly seems to have a much smoother  throttle response than before from 60mph in 5th gear.  :riding:

Thanks for the help and encouragement.