I recently bought my first K100 and have noticed that it seems cold-natured. This may be normal for these bikes but I suspect I have an issue somewhere. The "choke" doesn't have any effect on the idle speed even though I've adjusted it somewhat. The bike runs poorly until it's warm but then runs exceptionally well, reaching far more than posted speed limits with ease. It has a new fuel filter, new plugs, and all new fluids. I also replaced the vacuum caps on the throttle body and the crankcase breather hose. I've spritzed various carb and brake cleaners around the throttle body while the motor is running without any effect and can't see any arcing from the plug leads. Does anyone have any idea what I should try next or am I worrying about nothing.
Thanks!!
Al

Hi again Al,
Good qustion. My RT had the same idea. It would run rough when cold, then 5 mins driving and it was fine. The choke did work, but it never stopped the problem. Not a problem really, just a bit of a pain. The RS I have now is exactly the reverse when starting. No choke needed, and don't touch the throttle!! Floods with just a twist of the wrist when turning it over to start. Once going its fine. Any advice from anybody out there would be most welcome.
Cheers, Boris the Bike

Hmm, may be just one of the quirks of the K-bike. After doing some reading on this forum I discovered that one of my coils may be bad, at least the ohms measurement differed between the two. I found a reasonably priced replacement online and hopefully that will help.

Hi Al,
First off you know you have a fault with the "choke lever" which is really only a fast idle control on these bikes. So I suggest that you adjust that to get it working it should raise the idle speed when cold that helps with running when cold. The engine electronics deals (or should deal) with the mixture to richen it when cold.

If you want to know for sure if you have a bad coil check the HT voltage by popping into a friendly garage with a SUN diagnostic machine, that will instantly tell you if you are down on volts. They may say we don't do bikes but the K 100 is really a car engine and electrics, it even started life with a Peugeot engine. A few beer should sort the price and you will know for certain if the high voltage is down at all on the secondary and if you need to buy a coil.

With a secondhand bike there are all the usual suspects such as people been fiddling with throttle position switch and worst of all been adjusting the throttle butterflies (the settings we are not supposed to adjust on any account ever) to try and set the idle. It is a major PITA when people think they know what they are doing and then fiddle around upsetting the correct adjustments. Sort of like the famous Jeremy Clarkson bit where a car bore he met in the US starts banging on about all the modifications he has made to the camber etc. on his brand new Lotus and Clarkson said "so you've ruined it then" much to the chagrin of the car bore.
Regards,
K-BIKE

Hi Boris,
With regard to your problem I would check the resistance of the two temperature sensors which are responsible ultimately for adjusting the CO and determine if they are correct, from your description it sounds like that is running rich.

If it is then the bike will be running too rich with the consequence that you are running poor or at least poorer than you should be.

I have also seen that happen when people have had an air leak which gave poor cold running and richened the mixture up had the leak fixed eventually, but never reset the mixture.

Could be the temperature sensors, a resistance check will say for sure, if they are OK check the CO value with an exhaust gas analyser that will point to what the mixture is and it may be just you need to tweak the setting on the air box.
Regards,
K-BIKE

KBike
Thanks for your input. I'm certain that the TPS had been fiddled with. Everything I've read says it should click but the way mine was set when I got it there was no click at all. I set it according to the instructions in the Haynes manual and hear the click now but the running symptoms are the same. My attempt at fast idle cable adjustment didn't help as much as I'd hoped. I removed the lower LH fairing piece to replace the vacuum caps but I don't know if anyone ever changed the butterfly settings. From the looks of things I really don't think so. The bike had one previous owner who passed away a few years agoand then the bike sat unused for at least two years. Could partially plugged injectors cause this problem?
Al

Bikes that have been left to stand for some time (or just older ones) suffer from contact deterioration in all the connectors. On carburator bikes maybe not so much of an issue, but our K's are fitted with fuel injection that is based on a lot of different sensor inputs. These are all connected over various connectors to the FI brain. Therefore there are two things you need to check first on poor running bikes, after you have made sure all (throttle, choke and clutch and TPS) have been adjusted correctly (but that's a given, isn't it ).
1 - Check for air leaks. Most suspect is the crankcase breather hose, vacuum point plugs or line and the throttle valve stubbs (where they meet the block). A rough check is to loosen the filler cap of the crankcase and see if the running changes. If not you have an air leak.
2 - Most important for the fuel mixture (which basically is the amount of fuel injected for an amount of air in this case) is the coolingwater temperature sensor and the air mass meter (and air temperature) signals. My understanding is that the coolingwater temperature sensor is one of the most important for idling as well as revved control. It seems that the other sensors are possibly less important at idling. So make sure all the connectors are cleaned. Bert has a good flowchart idea on the site to help as well.

Cheers, Rene

Thanks K.Bike and ReneZ. Things to check out. I'm learning...
Just a dumb arsed qustion here, but the temp gauge needle developed a quiver, flicker, what ever you want to call it. Then both the fuel and temp gauge just stopped working. It has happened before, on/off/on/off, but I thought it had vanished when I did the clutch work and then it worked fine for the last 2/3 months after reassemly. Thought I had mended the fault by default. Then the temp gauge started its quiver and it all just stopped like the old mans clock. Is there a chance it is all connected, temp sensor fuel mix and the dials? Stupid qustion it might be, but it just might be the source of the trouble as well?
Cheers BTB

No stupid question at all. They all use the same ground connection to the frame for instance. Both the fuel and temp gauge are connected over the same piece of wire loom and get their power and ground through it. If you haven't done so I would start by removing the tank and cleaning all connectors, paying particular attention to the grounds to the frame underneath the tank and on the gearbox. Cheers, Rene.

After cleaning a zillion electrical connections and wearing out a couple of multimeters I finally got around to checking the fuel pressure and Bingo!! Pressure was about 25 lbs. Finally tracked it down to a cracked fuel filter. I wouldn't have thought it was a fuel problem since the bike ran great when warmed up and hit 100 mph with ease but who cares, it's fixed!!

"Then both the fuel and temp gauge just stopped working" - I would have never thought the cause for thaty could be a cracked fuel filter ;-)

"Then both the fuel and temp gauge just stopped working"

No, no, no, that was BTB's bike that had that problem, mine was just "cold-natured" but that's all fixed now. Thread hijacks get confusing
Thanks to everyone for the advice!!

Al

Shit happens!