Hello everyone,

Just picked up a 93 K75s with around 42K miles that had been sitting for about a year; she is very un-willing to accelerate under load. When the bike is on the center stand, it revs just fine (most of the time), but when taking off, she will hesitate and completely die sometimes. It also idles around 2K with the fast idle (choke) disengaged and engine fully warmed up, and the idle screw up, so there is something else happening. When accelerating, the engine wants to die, unless I back down and carefully twist my way up. It will accelerate even when I am riding it, but after about a minute, it will just run out of power and slowly die.
I have all service records and the bike was well maintained; the only issue was that the previous owner complained about hesitation and asked the dealer to check the injectors, they did and found nothing. Not sure why they didn't investigate further. I read some previous posts on this forum and tried to resolve this problem without having to post a new topic, but was hoping to get some direction before spending more time and funds.

This is what I have done so far:

1- Completely re-charged battery (engine turns over crazy fast)
2- Checked old fuel in tank; the fuel looked like apple juice
3- Removed all the old fuel from the tank
4- Added 2-gallons of fresh good quality fuel
5- Added a bottle of Heat fuel water dryer
6- Ran the engine for a very long time, and took it out for a ride a few times
7- Checked Plugs-they were sooty and black, not wet-sanded them with fine sandpaper, cleaned and re-installed
8- Checked Plug cables, tested OK, but why the last cylinder closest to the coils has the longest spark plug wire is beyond me
9- Checked Fuel injectors-cleaned, soaked in carb cleaner overnight, used 9volt batter with connector to apply voltage to each injector, they seemed to operate and fed more carb cleaner through them while voltage was being applied
10- Re-installed injectors and tested them on the rail; they injected all at similar rates while trying to start the bike
11- Replaced a cracked S shaped hose that seems to connect the air cleaner housing to the throttle-body
12- Checked air cleaner- still looks new
13- Oil level was a little high-it was past the high circular mark, removed excess oil
14- Checked all hoses around the throttle body and air filter housing, they seem OK (but I have not removed the tank yet for a closer inspection)
15- Used the propane trick around the throttle body, air filter housing area to see if engine RPM would rise without any luck
16- Fuel pump seems to work; it runs on for a second or so after engine dies (obviously more testing needed here)
17- Checked the tank and the 2 new added gallons of gas looks a bit murky (possible old residue in the system)
18- Checked exhaust- it does not smoke (not that I can tell at least)
19- When opening the tank lid, it does make that air surge noise

Since the fuel was replaced, it runs much better, but after all the other work, the rough running under load still persists.
I think that is all I have done so far.

Thank you all.

Aron

If the fuel in the tank was that bad, your fuel filter (in the tank) may need replacement. A blocked filter will affect the pressure the pump can deliver to the injectors.

Disclaimer: this is just a wild grab based upon the information you have provided. There are many other potential causes of your symptoms and there is truly no substitute for working through everything in a methodical manner. My money is on your fuel filter being at least part of the problem though...

I agree too about replacing the fuel filter but you should also check the air vent on the tank. The tank should not be under negative pressure. You should try to run the bike with the gas cap open.
If I recall correctly, the gasket under the gas cap has a hole that should be lined up with the vent hole on the tank. This gasket maybe in the wrong position.

What Bert refers to is a little drain pipe fitted on the left side of the gas cap that drains out of one of the little pipes on the right rear bottom of the tank. The other pipe in that location is for breathing of the tank.

The high idle and not picking up whilst driving could be a faulty fuel pressure regulator or still leaks in the air system.

Start with the basics - clean electrical connections, measure resistance of the water temperature sensor, see that the air mass meter is freely operating and check the engine adjustment.

Thank you ALL! I will start out with your recommendations and go from there!

Aron

By the way, I found out why the fuel looked like apple juice; the previous owner put some additives to remove condensation (he thought condensation had formed and was contributing to the rough running).

Aron

Hi netaron,
The above points the guys make are all excellent and first to do items. The next is to work through the trouble shooting menu in the download section. I would also take a look at the fuel pressure with a gauge because if there was suspect fuel it could have caused the fuel pressure regulator to be jammed at some incorrect pressure. It is fairly easy to do and really worth doing because it tells you if the regulator & pump is working OK if the pressure is right.
Regards,
K-BIKE

All right gents; I finally emptied the tank with the gas lid off to get a good look; looks like the bike either sat too long or it was a case of bad gas. Anyway, cleaned the tank out, replaced the fuel filter and she is purring again. Still revs at around 2K, but I have not had time to take her for a good long spin. Thanks again for everyone's help; I will keep you posted.

Aron

OK, she runs fantastic!!!
The only issue I'm having is with idling;it idles around 2K.
Any thoughts?

Thanks.

Check that in the fiddling about the throttle cable outer has not slipped position so it is hung up with the result you are effectively holding the throttle open. I have had that happen on another engine, the cable outer came out of the ferrule on the outer end with the result the outer was perched on the shoulder of the nipple = high idle.
Regards,
K-BIKE

Good point K-Bike.
This is the same for the choke cable.
The other adjustment to check is the throttle position switch. If improperly adjusted, it could prevents the throttle to close.

OK; cables all seem to be in the normal positions, including choke cable. I disconnected the throttle position switch wiring harness to see if a change would occur, nothing happens when it is disconnected and reconnected. It does "click" as I just move the throttle up slightly; any thoughts?

Thank you all!

Aron

You should slack the 2 screws holding the throttle position switch. If it's not set properly, it may prevent the throttle to totally close (it acts as a mechanical stopper).

i wonder it the idle adjust screw on the throttle linkages (about the middle ) has been adjusted to compensate the poor running by the last owner ?
after hearing that the tps is working correctly , this could be a simple solution ...

charlie99 makes an extremely good point all too often when we come to a problem on a bike we have taken over,. once that is fixed and returned to standard we find a preious bodgy owner has fiddled with settings to get the bike to run despite the basic problem. Then once that is fixed it no longer runs properly because it was fiddled with so fault finding in a series of ever decreasing circles gets done until finally all is stndard and it is working. The problem is most previous owners don't diagnose, they take random guesses and try adjusting things rather than stopping and thinking it did run perfectly, now it does not, what has changed. There is that tempting array of adjusters across the throttle bodies all crying out to the bodgy owner, "adjust me - adjust me" and they finally yield to temptation with the result of all unbalanced air flows
Regards,
K-BIKE