1984 k100, So after sitting for seven years we have an MOT, however the twenty mile trip to the station was horrible - feels like its running on three cylinders, almost in 1st gear on a steep hill, vibration everywhere, my thoughts are still injectors or vacuum controller or leads or air leaks?? any ideas on what to check first

vacuum hoses have been replaced, i've got the crank case breather coming (it feels worse than an air leak) so injectors and a pressure valve i guess.

I'd check first for a decent spark at each cylinder as that is the easiest initial step.

When I purchased my own '86RS, it hadn’t been used for 10 years and the petrol in the 1/3 full tank had turned a deep yellow and the rubber parts inside tank had really suffered – fuel lines were liquorice and the pump damper/holder had turned to goo. The fuel pump was jammed so my problems were more obvious than your own. This is a very common fault for laid up K-bikes and quite a few tell the same story on the forums. I recommend you examine this area even if it isn't the root cause. You wont have a totally jammed pump but the filter and the fuel supply system might not be as efficient as they could be.

Iain is exactly right with that. If the Ks sit for any extended time ALL the rubber components deteriorate and need replacing.
Clean the injectors with carb and throttle body cleaner. Use a 9volt battery to keep the injectors open or they wont get clean (DON'T use 12 volts as they WILL overheat and burn out). Replace the rest and they wont run very well (if at all) at all unless the Z shaped breather hose is there and airtight.
One thing you need to be very fussy about on the K100 is that the air induction system does not leak.

Thanks guys, the bike had sat for 7 years, pump was replaced along with all the fuel pipes and vac pipe, fuel and air filter, etc. the z shaped pipe i guess is the one i have coming crank case breather. Is there a list of cars that use the same injectors ? alfa and seat ?

RicK G wrote:Iain is exactly right with that. If the Ks sit for any extended time ALL the rubber components deteriorate and need replacing.
Clean the injectors with carb and throttle body cleaner. Use a 9volt battery to keep the injectors open or they wont get clean (DON'T use 12 volts as they WILL overheat and burn out). Replace the rest and they wont run very well (if at all) at all unless the Z shaped breather hose is there and airtight.
One thing you need to be very fussy about on the K100 is that the air induction system does not leak.

Hi Rick,

What do you mean keep the injectors open with 9v and how is this done. My K100rt 1985 is running a little rough at moment too. Changed crank case breather hose ( Z ) and is air tight. I notice the rough running is exacerbated when cornering/leaning over  : (  

Andrew

If you put the carb cleaner into the top it wont go right in because there is limited space to get the air or old fuel out so you need to keep the valve open and the way to do that is connect a 9v battery from a smoke alarm to the 2 contacts at the side where the ECU connects.
Remove the injectors and take the O-rings off and the small strainer out the top (use a self tapping screw, screw it in a bit then pull with the pliers or put the screw head in the vice and yank it).  Get a set of the O-ring kit  which has the small strainer in with it and put them back on and in put some Vaseline on the O-rings and put them in the fuel rail, put the clips on and then put all 4 in the cylinder head together
Try to get the right connector from an old harness or many cars have them so go to a wrecker.
Connect the 9v battery (polarity does not matter) so the pintle valve is open as if it is injecting fuel and spray the carb cleaner in then take the battery off and let it sit for 10 minutes or so then do it again and watch the colour of the crud that comes out. Do it a couple of times then blow it out with compressed air with the pintle valve open.
Firstly clean around the injectors and blow the compressed air around the injectors to be sure no sand and dirt gets in when you remove the injectors. 
http://www.ebay.com.au/itm/Fuelmiser-Fuel-Injector-Service-Kit-ISK-0515AX-For-BMW-3-Series-E36-91-99-/152247635370?fits=Make%3ABMW%7CSubmodel%3A318i&hash=item2372aa8daa:g:CbYAAOSwn-tZHxmc

Rick - how do i know if the vacuum valve is working correctly ??

timo27 wrote:Rick - how do i know if the vacuum valve is working correctly ??

I am presuming you mean the pintle valve, it will click when you apply the 9volts. The thing is in effect a solenoid valve that has the opening duration controlled by the ECU.

Sorry I meant the pressure regulator which has the vacuum pipe on it coming from the forth barrel / inlet. I pulled the vac pipe off whilst it was running and i made no difference the poor running. Is it just there to maintain pressure in the injector rail? could this be stuck shut and if so would the engine drink fuel at a higher rate?

If pulling the vacuum tube off makes no difference check that the little brass stub isn't blocked and if that is OK then you have serious air leaks in the inlet system. Air leaks are very common in the early Ks. Remove air box to cylinder head and check all the flexible parts for splits around where the clamps go and every joint for loose and cracks.
Some of the clamps are Otiker type and can't be reused so these Suzuki clamps will do the job well.


48mm Suzuki band clamp   Part# 09402-48208 Cost about $4.75 each.
When replacing be careful not to snag with the throttle moving parts.