Hi everyone Im new here due to me buying a 92 k100 3 days ago it has been of the road for a few years its had another engine put in it then it was left till i brought it. Anyway i took it for its mot today which it passed no probs but when i rode it home i got on an open bit of road so i wound her open it got to about 4000rpm then it was like someone turned the ignition off anyway it cutout for about 2 seconds then it come back to life while i still had the throttle open and it nearly chucked me off the back lol anyway does anyone have any ideas what this might be? The speedo dosent work either does the ecu use information from the speedo as information to help with running like some cars do? Also the wiring isnt the best ive ever seen but it runs well apart from this do the airflow meters give trouble. I e maybe a dead spot in the track inside it? any help would greatly appreciated. regards terry

Hi Ya Timmy good to have you with us and to see another K100 revived.
It would probably pay to post in the intro section as you will have access to the downloads then.
You say the wiring is not good and I would say that is where the problem lies. You will see a product refered to here called DeoxIT and it is the next best thing to a magic wand for cleaning electrical contacts and connectors.
The first place I would look is the connector which is from the fuel tank & pump and under the right side cover. Make sure it is clean and the pins haven't expanded on the female connector so that the male one doesn't contact proprely, you may have to gently squeeze the connectors closed a bit as they do open a bit with use.
There are many connectors under that side cover and the speedo is one of them (a small 2 pin). Also under the tank is a good possibility for bad connections as there are heaps of them there. Go over all of them with DeoxIT and you will most likely have a sweetly running bike.

Welcome aboard Timmy. These are pretty powerful machines that could be pretty dangerous with the throttle on and off like that. K Freak has got you off to a good start in solving it.

I'm with K Freak all the way on this one - check/make good all electrical connections that you can find with DeoxIT. These old K bikes have been around a long time and if neglected they are subject to all sorts of gremlins, especially within the electrics. Welcome aboard by the way - you can be sure that if you have any sort of issue with your new "K bike" that somebody here will have already had the same issue and documented the fix somewhere on this site!

P.S. Nice to see another UK member joining the ranks

Hi Timmy and welcome from the land of perspiration and storms at the moment.
The biggest threat to us all it seems is to think that everything is too complicated, and the worst must be happening. If you take some time and read through some of the calls for help in this forum, you'll see that most of the problems end up being rather trivial and easy to fix. Clean everything like K Freak said (if you are in under the tank do every connection you can find), and read Bert's wonderful fault finding guide.
All will be revealed.
RT

Hi all thanks for the warm welcome. As you say I think that wiring may be the problem here I lifted the tank earier and boy is it a mess tape everywhere cut wires just left dangling about. In all fairness the bloke i brought her off did say it was a project and ive got to strip the tank and all fairings off over the winter as she needs a respray so i can tidy up the wiring and try and find where the loose ends go things like thee clutch switch wires have just been cut and left. Does anyone know where these should go? Ie are they for the engine management or are they a safety device for the side stand like many jap bikes? Also can anyone point me in the direction of a good quality wiring diagram? I must confess that im a car mechanic anyway and we specialise in tuning and other work in old cars and things that most wont touch so im not totally in the dark and the more i get into it i see that it isnt much differant to any bosch motronic efi used on most cars thoughout the late 80s and into the 90s. However i like to go into a job with as much knowledge as possible and i dont want to just chuck parts at the problem especialy if its just wiring. The main problem is testing the bike as the above poster said it is a dangerous fault on a big powerfull bike to have it cut out then go again its one of them brown undies moments so im keen not to try it to often lol. thanks again guys I will post any new developments asap:D

I had the exact same thing happen to me, it ended up being the ignition, it would cut out, i would turn the ignition off and on and it would work again.

There is info on here how to strip it and clean the internals, but as others have mentioned strip and clean everything, wont hurt either way.

With the mess of wiring it sounds like it was an ex police and as usual they just cut the wiring and insulate if they have to and stuff the thing back together.
The speedo is an easy way to tell if the speedo is graduated in 2kph marks it is police and if 5kph graduations it is normal retail version.
I know this doesn't help with the problem but at least may explain some of it.

Ex police bikes have had things chopped off them before their disposal to civilian life, did not know about the 2kph increments on speedo, mine has this but I thought they all did, I've heard the final drive ratios are different also.

Regards Bushy

Ex police bikes speedos are definitely graduated in 2Km increments. Non-police machines are in 5Km increments. Gospel!!

hi timmy ......welcome to the forum ...

there is an exellent wiring diagram here ....but to access it you will need to post in the " members introduction " section http://k100rt.aforumfree.com/f1-member-s-introduction

after a few more posts you will be granted access to the downloads section ...in which is a really excellent interactive diagram of the electrics ....and much more info ...

good to have you aboard

usual behaviour for untended el. connectors, switches ect
before spending money: complete service all along the bike


very often:
right switch unit.
either open & clean & grease (uncertain result - because of flying springs nupsies ect)
or: exchange the unit complete - expensive but save

nice and my job for the winter:
dismounting ign. switch

When i bought my first K100 six years ago it suffered form the same problem after a couple of weeks of ownership. After a lot f internet searching and advice I was directed towards the starter motor brushes. Apparently when they wear down the can cause a number of wierd electrical issues. It took 30 minutes to change them and it cured the problem.

I would go for sorting all wire earth joints and treat every connector on the bike with DeoxIT as a starting point.
Regards,
K-BIKE