Hello,

So, a quick back story: I bought a 1992 k100rs that had no compression on the first cylinder. The bike did, however, start and run on the 3 cylinders. I then bought a 1991 k100rs engine that was tested good and swapped it in. Now that I've got it all back together and ready to turn the engine over, I've got issues.

So here's what's going on. When I turn the key and flip the switch to on, everything looks normal. The dash and instruments light up like normal, the neutral light comes on, etc etc. When I press the starter button, however, everything shuts off (which, from what I understand, is also normal) and I hear electrical noise from the fuse box. Then smoke . I traced it down to what I believe is the starter relay. Everything in the fuse box has been left alone in the entire process and, as such, the wires coming from the starter relay(?) match the wiring diagram. I believe I have everything else hooked up correctly as well, but that is obviously not the case.

Here are some pictures of what it looks like.






Could it be something else that is less apparently related to the starter? Also, there are two 'terminals' on the back of the starter where wires are connected to. This is, I believe, how it was before I took it all apart. The only reason I mention that is because the wiring diagram only shows the black wire coming from the starter relay and then one more black wire going to a 'relief relay'.

Please help!

The 6mm diameter black wire onto the starter, remove it from the starter terminal and push the starter button again.
Does it smoke NO Starter at fault, YES remove the same wire from the relay. Does it smoke when the starter button is pushed NO the cable is short to the frame or engine YES the problem is in the relay.

Ah, thanks so much, sounds good. I will definitely try this in the morning. Just to be clear, the 6mm wire is the one on the top of the starter that goes to the fuse box, correct?

Rabidchiwawa007 wrote:Ah, thanks so much, sounds good. I will definitely try this in the morning. Just to be clear, the 6mm wire is the one on the top of the starter that goes to the fuse box, correct?

Yes thats right.
The other two wires are earth/ground that make sure the coils and the ignition amplifier will work and could not be the problem.
I have a feeling that the black (6mm) will be pinched against the frame under a bolt or similar but that is instinct from half a world away.
If the starter turns out to be faulty then use a jumper lead to briefly connect the terminal to the battery Positive terminal ans see if the starter wants to turn the engine.

Have the "new" engine been sitting for a longer time, have you tried to turn it by hand?

It has most likely been sitting for a long time, but yes, it is free. I took the spark plugs out, put it in gear, and can roll it with no problem while in any gear.

Could also be that something in starter gear mechanism is stucked.

With spark plugs out, try to turn the back wheel in both directions by hand.....
it should be only slightly more resistance when the wheel is turned backwards.

Interesting. So I figured I'd give that a go. I put the bike in 2nd gear and turned the rear wheel by hand. There was some degree of resistance turning it forward, however turning it backward was quite difficult. I would say, maybe, twice the resistance versus turning it forward.

Upon turning the rear wheel backwards, I heard a sound coming from the starter (I think) which basically sounded like it was rotating slowly. I did not get this sound when rotating the wheel forward.


Also, results from cable tests:
-With cable unplugged from starter but still plugged in to relay: No smoke from starter relay
-With cable unplugged from relay but still plugged in to starter: No smoke from starter relay


Based on that, and the resistance from the starter while turning it backwards, it isn't looking to good for the starter is it?

The backward resistance is due to the one way clutch which engages and turns the starter so that means the one way (sprag) clutch is working.
Pull the starter off is the next move.
To do that the battery needs to come out then undo the 2 socket head screws (the ones with the brown wires under the head) and the 6mm cable then the starter should come out bu moving it backwards about an inch. This is easier said than done and you may need to use a lever while wriggling it around a bit and they usually come out fairly suddenly.

Rabid,

When you take out the starter there should be an o ring on the end of the shaft....just make sure it does not fall out. The starter needs a little wriggling to free it and if it comes loose suddenly your knuckles take the hit.

As an aside could load shed relay be stuck and cause this?

Yeah, I know how everything comes apart as I just finished getting the engine and transmission back in to the bike, so I'll be careful of all that. I certainly had plenty of knuckle hits in the entire process!

I was thinking of the relief relay as a possibility as well, but I have no idea what or where it is.

Just one more thought check that the terminal you put the 6mm cable onto on the starter is not loose in the housing. If it is loose it can move sideways and short against the housing. It has plastic insulators to prevent this but if the bolt is loose it can move enough to short out. You wont notice anything wrong till you hit the starter, even the loadshed relay will work as normal.

On picture 2 is the red cable melted, that would explain the smoke.

Good point, could be a idea to check if the cable is partially broken at this spot.

Yeah, the two cable insulations had melted together but I pulled them apart and made sure they weren't touching only to get the same smoke from the relay.

I did notice that when I was securing the 6mm cable to the starter, the terminal came loose. I thought I had tightened it up sufficiently, but possibly not. You said it can move back and forth and short on the casing, so do I need to watch for that as I tighten it as well?, to make sure that I don't end up tightening it against the casing?

Rabidchiwawa007 wrote:Yeah, the two cable insulations had melted together but I pulled them apart and made sure they weren't touching only to get the same smoke from the relay.

This indicates some short to ground (eg. the frame).

This is the circuit in question:



The melted wires are connected to Terminals 30 and 87. If the relay is still smoking, there is probably a short to ground on the wire from terminal 87, between it and the starter motor. The short is causing excessive current flow through the wire and there is no fuse to protect the wire, as you see in the diagram. If you have an ohm meter, check conductivity to the frame from this wire after disconnecting it from the relay. The short can occur anywhere along the length of the wire -- from the starter terminal as observed by Rick G. to the relay terminal. Check the entire length of the wire visually for more melted insulation and possible shorts.

Solved! I took the starter out and took it apart. All of the plastic insulation both on the inside and the outside of the starter's terminal was cracked and pretty much gone. So, I took the terminal out of the case, soldered the wire to the terminal a bit better as it was coming apart a little, covered everything but the threads in a couple layers of shrink wrap to keep it from making contact with terminal, and put it all back together.

I then bench tested it. Set it down on the work bench, connect the positive from an extra battery to the starter terminal, and then touch the negative to the case of the starter. It spun up no problem. So I put it back in the bike, hooked everything back up, and it's working normally again.

Now I just have to put some shrink wrap around that melted cable insulation.





I'm now waiting on the rubber boot that connects the clutch arm to the push rod. Anyone else think the design down in that area is kind of appallingly stupid? Using a paper thin rubber gator that's sealed by a moving part? Seems silly to me. And $42 USD for that rubber part didn't make it much better.

Anyways, thanks a ton, everyone! My turn to browse the forum and see if I can help out a little.

Nice that you got the problem sorted out.

Rabidchiwawa007 wrote: All of the plastic insulation both on the inside and the outside of the starter's terminal was cracked and pretty much gone.

If you buy a new brush set, new insulators is included.

Rabidchiwawa007 wrote: I'm now waiting on the rubber boot that connects the clutch arm to the push rod. Anyone else think the design down in that area is kind of appallingly stupid?

No, don`t share your opinion...haven`t been in the need to change this boot yet, during 26 years of ownership.

I have not had any problems with the rubber boot itself but had a leak there because the actuator arm was not sitting square due to poor adjustment.
At an age of 25 years they will be perrished but in good condition they do the job well.

Fair enough, I suppose, got it.

Now the only thing keeping me from starting the bike is that when I hook up the gas tank, the starter turns and there is spark, but I don't hear the fuel pump running, so there's no fuel delivery. Everything *seems* to be hooked up correctly according the wiring diagram, so I might be a little stuck. I'm think it could be a ground issue for the pump or pump relay, but it's not a ground to frame so it's tough to determine.

Does the pump turn for a couple of seconds when you turn on the ignition?

Nope, nothing when I flip the switch to on or while I'm holding the starter button. No pump at all.

Have you checked the sidestand switch?

That was one of my suspects, I just haven't had a chance to take a look. When I put the center/side stand unit back on with the switch, the switch doesn't seem to click the same anymore, like the button isn't being pressed by the straight metal strip / spring.

You could try to temporary bypass the switch at the harness, and see if that makes any difference.

The wires from the switch is green and green/red.

The connector you find under the RHS sidecover, and it looks like this:

Got it! Took that switch out all together and bridged the wires. The bike starts and sounds good. The only thing I'm concerned about is that I'll rev the engine to ~5000 rpm, and when it comes back down, it will drop below idle, stutter for a second, and then return to normal idle. (Engine is warm / normal operating temperature when this happens)

I'm thinking mixture, so TPS adjustment. But any other ideas?

Edit: It could also be that the timing doesn't return from being advanced in the high rpm. But if my thoughts on that are accurate, the timing is done electronically / by computer, so if this is the case, what would cause the timing to not adjust back upon slowing of the engine?

About the sidestand switch.....could be a good idea to try to get it functioning.
Often the only thing needed is some WD40, and a bit of workout exercise....
(on the switch).
Many years ago I did spend a couple of weeks in a hospital.............cause I did
forget to kick up the stand.......the switch is a safety device.

About the stalling, I do agree with you that it could be a idea to check the TPS
setting one more time. If it`s set to lean...and got a lambda sensor ...it would
take a short moment before the Motronic reads it, and then compensating.

Could also be a idea to check that the air bypass at the TB's is synced.
if not allready done.

That's something to start with, got no other ideas at the moment.

BTW. I don't think the timing should be suspected at this early stage.

check for vacume leaks on the inlet side of the throttle bodies ,,,,and the crankcase to plenum breather tube

dont forget to inspect the rubber boots off the throttle bodies themselves ( where you would do the syncing from )
just a suggestion

Good point, Charlie..........places to check for leaks is:
1. Rubber sleeves between TB's and intake stubs.
2. O-rings between intake stubs and cylinder head.
Which is the most common places for leaks on these models.

BTW. could be a idea to update your profile..........

that 16 valve or 1100 inge ...did i miss something ?... (oops looking at the elctricals ...i see more than the older k 8 valve bikes going on there )

those 16 valves have even a more complicated vacume system as in count of possible leak places ...maybe many years younger and not yet prone to full brake down ?

just sounds like a fluffy vacume system to me, by the description of the problem coming off revs to idle

yes agree better to update your profile rabid ...was reading '85 k

Yes, Charlie.......it is more this and that which can cause a leak on a 16V.
But I only did mention the most common places, where this problem usually first occurs.
And if...a leak, I would suspect that it would be underneath the TB's.


But it won't hurt to check the hoses from the oil separator to the TB's, oil drain hose from the separator, crankcase vent to the separator, FPR vacum hose, also.

Everything underneath the TBs is brand new. The rubber boots, the plastic inlet boots, and the O-rings under them, are all brand new parts.

I do recall seeing some cracked or slightly torn hose leading from the TBs to the front of the airbox, into a closed section inside the airbox, and then from there to the engine, but didn't think anything of it since it is above the butterflys. I would assume that this is the oil separation line and a leak could possibly cause something like this? Couldn't hurt to replace it either way.

I had problems with my K11 when I first got it and the leaks were there at that oil seperator lines but they had just come away from the TBs and weren't cracked or broken.