K100 not running on all cylinders, drastically underpowered.

[Chaosmoto]

Okay where to start, I just signed up as I've been reading the forums a lot in order to try and resolve some issues but since I can't find one that really fits I decided this was the best course of action.


I've been building 1985 k100 cafe racer for my friend for the past year or so in my down time, anyway I'm at the end stages and am having a few issues.


The bike was running reasonably well at the start of all this so I can't imagine it's anything major.


The bike starts up very easily, but sounds like it's not firing on all cylinders. It's also very very low on power. I checked firing order and spark plugs and they are good I believe. The plugs were a little black but have a very good spark. ( I did notice that it sounded and felt exactly the same when number 1 and number 4 leads were reversed )


As far as engine is concerned the only things I've touched during the build. Was pulling off all the intake and fuel rail. (I replaced the injector o-rings when re-installing) I also replaced air filter and oil filter as well as a new sump gasket as it was leaking. I've also drained and replaced all fluids.


Any help in which direction to head next would be much appreciated, I've also attached a couple of photos to show you the bike.

[Laitch]

Okay where to start, I just signed up as I've been reading the forums a lot . . .

Welcome, Chaosmoto! Looks like you've pared that bike down to the essentials—good looking. What speedometer are you using? Did you wire it up yourself? How many miles on the bike? How much was it ridden before you got a hold of it?
When you write that you "believe" something is "good", what is the basis for your belief—experience, appearance, professional reference manuals, instrument readings? If the "plugs were "a little black", does that mean sooty or oily? All of them or some of them?

You write that you're unsure which direction to head. This troubleshooting guide created by Bert Vogel contains much helpful information including an explanation of why there was no change in performance when you reversed the #1 and #4 plug wires. If it were my bike, I'd start at the top of the following list and work down it. The bike may start running well after the first few items or you may need to do all of it, and follow through with closer examination of individual components. Explanations are contained in the guide.

What is the battery voltage output?

Has the tank been inspected for sludge?
Has the fuel filter been replaced or it's age determined?
Have all electrical connectors, plug wires, coil connections and fuses, including the four pin connector under the tank, been checked and securely fastened?
Have all the rubber components been checked for leaks—the vacuum fitting caps, the throttle body bushings, the air box connections, the fuel pressure regulator vacuum hose?
Have the valves been adjusted and the throttle bodies been balanced?

If none of this has occurred, start at the top of the list and check off each until it is running better, finishing with the valve adjustment/throttle body balance.

Yours is not an unusual circumstance at all. I've read about it repeatedly. The reasons vary.

[The Mighty Gryphon]

Couple questions:

When you say the engine ran ok at the start, was this before you swapped out the instrument cluster?  How much of the wiring have you modified???

Does the engine idle smoothly?  How does it respond when the throttle is opened?  Does it act like it has a lean mixture, does it ping.  Does it quit?  Does engine speed increase? 

Check the MAF.  First thing that comes to mind is that the engine isn't getting air when the throttle is opened.   If the throttle butterflies are opening the flapper in the MAF may be stuck in a closed position.   

[Chaosmoto]

Hi, thanks for the very detailed responses... I've only got a couple of minutes before I need to leave for work so I'll try give as much detail as I can.


I didn't examine for sludge in the tank but I did drain it at the start of this, and the bike was being used daily before the build.. I put fresh fuel in when I was ready to start it a couple of weeks ago.


All four spark plugs were identical... A little damp, looked like fuel wetting the carbon build up.. Plugs might be old so I'll go ahead and replace them anyway. (Can't see it hurting)


The firing order is correct I believe, 1 at the front of the bike through to 4 at the rear. And those leads go to 1 on the outside of the front coil and 4 on the inside, 2 on the outside of the rear coil and 3 on the inside. Read on a couple of different forums to get the information for that.


I have checked most connections as I cleaned them all up pretty good when first installing. ( the whole bike was filthy when my friend first bought it to me, looked like it had seen a lot of dirt roads in its time )


The speedo isn't wired in yet. But it's just a relatively cheap one off eBay. (I'm not supplying the parts) but it's got a sensor for the front wheel for speed and I'm planning on wiring in the taco straight to number 1 lead once I get the bike running properly.. For now the only mod in the wiring is tricking the bike into thinking the clutch is always in, a temporary measure while I sort out the kinks.


Haven't checked for vacuum leaks or looked at the mad yet so I'll move to there I think. I did notice that that the 4 clamps on the inlet boots, (so the lowest ones) were all missing when I got the bike from my friend but since it was still running fine I didn't think anything of it.


I've replaced all the vacuum lines inc the the ones that block the ports on the throttle bodies, and I've replaced the crank case breather line too.


Anyway, I'm late for work now, so I'll have a look at the guide when I get home. Thanks again!

[Martin]

I use a laser temperature gun to check when cylinders are firing or not. Just point it at the header pipes one at a time, a non firing cylinder shows up significantly colder. Had mine quite a few years cost was $50 to $60 Au but now they can be had for as low as $17 Au local free delivery or $13 Au free delivery from China check Ebay. I use mine at least 4 or 5 times a year to check things like air conditioning and thermostat opening temperatures,radiator temperatures.
Regards Martin.

[Chaos]

Could be one of the coils is not working

[Martin]

The bike starts up very easily, but sounds like it's not firing on all cylinders. It's also very very low on power. I checked firing order and spark plugs and they are good I believe. The plugs were a little black but have a very good spark. ( I did notice that it sounded and felt exactly the same when number 1 and number 4 leads were reversed )

Could be possible fuel injector problem.

[Chaosmoto]

Hey thanks for the input, as far as I can tell the coils are fine as when I checked for spark I used the lead for each spark plug, therefore roughly testing the coil and lead at the same time.. Unless they can fail but still produce a good spark?


Thanks for that, I might look into buying one of those laser guns, seems handy especially when you consider that price tag.


Also to check the injectors should I just leave everything connected but remove fuel rail and crank the bike to see the spray they produce?


Thanks again

[Martin]

There are quite a few posts on how to clean and test injectors on the net. I have cleaned mine a couple of times in the 19 years that I have had the bike, I am not recommending you do it the way I do. I use an Aldi ultrasonic jewelry cleaner with cheap injector cleaning solution Valvoline $6.00 Au from Repco. You can use a small 9 volt battery to cycle the injectors while in the ultrasonic cleaner ( Extreme care is needed you do not want any sparks while you are cycling the injectors).
Cycle ( 1 minutes per cycle ) the injectors both open and closed then remove from the cleaner and with the injectors open blow them out in reverse. You can then test to see if they have a good pattern by spraying them into a jar one at a time. Do this connected to the bikes fuel line omitting the fuel rail you will have to do a bit of adaption to get the line onto the injector. Connect the bikes harness to the injector and holding it in a clear jar and press the starter, compare the pattern between the three. Again extreme care is needed if you do this and again I am not in no way recommending you do this. What is your location in Brisbane just in case I can help at anytime, suburb will do.
Regards Martin.


 

[Chaosmoto]

Okay so I think I've found the problem... Just let me know what you guys think.


I checked the maf first up and the flap was moving freely, nice and easy and smooth, so then I went to the injectors... I pulled off the fuel rail and flipped them so they were facing outwards, and then I got an old clear fridge draw and put in place so the entire fuel rail and injectors were inside and I could see what was going on while I cranked the bike over. I have two injectors firing a pitiful amount of fuel, and in more of a stream form then a spray the other two not doing a thing.


So then I went out and got some fuel injector cleaner and did all the things I was recommended not to do by Martin. Put it all back together and repeated my first test... If there was any improvement I'd be surprised.


So is it worth taking them to a shop and seeing if they can work some magic on them or should I let my friend know the bad news and tell him we have to get a new or second hand set of injectors, if that's the case has anyone had any luck with the ones from the states on eBay..  I'll post the link to show you which ones I'm taking about.


https://www.ebay.com.au/ulk/itm/231974623891

[Martin]

If you didn't get any spray at all on two, try swapping their position with the ones that did spray, it could be a wiring fault. Also try soaking overnight, you have nothing to loose. There are alternatives to the stock injectors Ford 4.9 Lt F1ZZ9F593B and BMW E30 4 pintle hole sorry don't know the number.
Regards Martin.

[Chaosmoto]

Good idea, I'll go do that now and see what I get... In the meantime any thoughts on those new injectors would be much appreciated.

[Chaosmoto]

Okay just tested it again, and the same two injectors are working exactly the same no matter what position they are in... So it's definitely the injectors... I'll soak them in the cleaner over night and then give them another go through the ultrasonic cleaner and see what I can come up with.

[Martin]

0280150705 is the original part number and suits quite a few vehicles in OZ. The listing you are looking at seems dear, but it also shows alternative part numbers for the injectors. I would try local injector shops first to see if they could be had at a cheaper price, or try for a low mileage set at the wreckers. There is also a shop in  Wolverhampton St Stafford that does second hand BM parts. It's called the BM shop run by a guy called Chris, who is helpful but he knows how to charge. Also try putting a multimeter across the two terminals and measure the resistance I can't remember what they are supposed to be but you can compare the good ones with the bad ones. If they are  not in the same ballpark you are flogging a dead horse. I will try and find the resistance and post.
Regards Martin

[Martin]

Resistance should be 16 Ohms.
Regards Martin.

[Chaosmoto]

Thanks for the info... I believe I have to salvageable injectors and two ruined ones. I say that because I have run the two that were firing through the ultra sonic cleaner for another 3 mins each and now have a decent enough spray pattern, the other two however i have only just noticed arent opening or closing when connected to voltage. so ill see if i can find a couple of second hand ones for sale. dont suppose anyone in oz has any spares lying about? thanks

[Chaosmoto]

Also the two good ones are showing 16.4 and 16.5 ohms resistance and the two bad ones are both showing 16.7.. Thoughts?

[Martin]

The coils are OK so I would continue to try cycling them while in the ultrasonic bath alternate between open and closed. Be careful not to spark. The injectors do have replaceable filters which can be removed by screwing in a correct sized self taper and pulling it out. Try removing the filter ,
new ones are available.  The hoses and the rubber damper are known to disintegrate when subjected to E10 fuel, which blocks the injectors check your tank.. Use only SAE30R10 submersible hose in the tank. It looks like you have a severe blockage you could try blowing back and forth with compressed air while opening briefly with a 9v battery. If not submerged in fuel or cleaner do not apply battery for long periods, just short bursts, without coolant they can overheat the coils. You could try Chris BM Shop PH 3356 6128 but remain seated when he gives you the price., although he has surprised me a couple of times. You haven't given me what suburb you are in, but that's OK.
Regards Martin.

[Chaosmoto]

Awesome thanks for that, I'm in westend... I also noticed that on one of the bad injectors the green cap has a crack in it, are these replaceable if I manage to get them going again?

[Martin]

Caps "O" rings and filters are replaceable I used to get mine from a BMW car non dealer specialist but he's no longer around. Let me know the condition of the filters. I think I used a sheet metal self drilling & taping screw to get mine out. Try the internet if you have trouble getting them out. I also have some specialist tools if you get stuck valve tools, clutch aligner tool etc.
Regards Martin.

[The Mighty Gryphon]

Looks like the coils are ok.  I wouldn't give up on those injectors yet.   As suggested, pull the filters, and with 9v on the coil and blow some aerosol fuel system cleaner through them.  For the cost of service or even a used set it's worth spending a little time cleaning them out.

[kennybobby]

i use Berryman's carb cleaner in a syringe to force thru the injectors while putting 5 to 9 volts on the injector terminals.  Try pressing on the pintle to see if you can get it to move slightly--examine the good ones to see how they stroke with voltage and compare to the stuck ones.  If you can get some strong solvent in there they should open up again.  Berryman's will burn your skin, eyes and lungs it is strong stuff be careful.

[Elipten]

Send to me injector for cleaning


Sent from my iPhone using Tapatalk

[PaulP]

Ay-oop, logged in for a quick shifty on here, perhaps it's some help.....?

Method is half way down-ish.

http://www.motobrick.com/index.php/topic,8946.msg70208.html#msg70208

[Chaosmoto]

This afternoon, I managed to get the injectors all firing, maybe not the perfect pattern just yet but hey they are working again!!! I'll clean them again once I get the new caps and filters for them, but for now the bike is back running on 4 cylinders which means I can start working on the rest of the bike. Thanks everyone for the input and advice...