OK to crank engine with spark plugs connected resting on the cylinders?

[milo]

1993 R100 and I want to check if there's spark.
Yesterday after washing the bike I started it on 1/2 choke like always and it fired right up. After about 5 seconds it quit suddenly. It wouldn't restart not even one putt, as if the kill switch was on (but it's not). After a few more attempts (never one putt) I gave up, pulled it back in and connected it to the Tender. Today before trying again I checked that the float bowls were full and they are so it's getting gas. Removed the tank to see if a connector came loose but everything is tight. I'm not sure what to do next other than see if the plugs are making spark, hence my question. Any suggestions appreciated.

 

[20774]

As to the plugs, be sure you firmly ground the threads of the plug on the engine case.

 

[pglaves]

As to the plugs, be sure you firmly ground the threads of the plug on the engine case.

I ground the plugs with a jumper wire: firm on the plug threads and firm on a known good chassis ground.

 

[milo]

Kurt and Paul thank you. I have little motorcycle battery jumper cables which could clamp on the plug threads and engine. I have a feeling there won't be spark.....

 

[pglaves]

Kurt and Paul thank you. I have little motorcycle battery jumper cables which could clamp on the plug threads and engine. I have a feeling there won't be spark.....

Those cables would be perfect for the task. Do the test and go from there.

 

[ksdcr]

Long shot, but since you just washed the bike, I’d check the fuses. Possibly moisture got onto a main fuse, and it’s shorted.

 

[stevenrankin]

Moisture

One thing about your bike is the bundle of snakes that is the main harness and relays and such in the pre 85 bikes has been moved out of the cramped headlight shell. Makes it easier to work on. BUT, it also makes it easier for water to get into place in relay plugs that may have been better protected inside the headlight shell.

As mentioned check the fuses. I would also perhaps pull the relays out of their plug blocks and check to see what shape the terminal spades are in. Good luck. St.

 

[ksdcr]

One thing about your bike is the bundle of snakes that is the main harness and relays and such in the pre 85 bikes has been moved out of the cramped headlight shell. Makes it easier to work on. BUT, it also makes it easier for water to get into place in relay plugs that may have been better protected inside the headlight shell.

As mentioned check the fuses. I would also perhaps pull the relays out of their plug blocks and check to see what shape the terminal spades are in. Good luck. St.

Thanks Steve, I meant to mention the fusible links as well.
They certainly could get some water intrusion.

 

[milo]

Thanks guys. When I get out there I'll hit the starter again just to "see" if it straightened itself up. Then I'll check the fuse and connectors, I hate to ask but "what is a fusible link and where are they?"

 

[stevenrankin]

fusible link

Not having the bike at hand I would guess the fuses and their sockets are in the cluster of "stuff" under the gas tank. LOL sure beats having to remove the headlight to check fuses and try to work in that space with ham hands like mine. St.

 

[milo]

No spark on either plug. I just checked the fuses which are behind the left side cover (are there others?). There are (4) 15 amp and they are ok, not a spec of dust, moisture, or corrosion in there, it's nicely made, well sealed fuse box.

I doubt if both plugs or plug wires would fail at the same time so it's probably not them.

 

[stevenrankin]

Research

Both plugs not sparking is not good. In around your year of manufacture, I remember hearing about a problem with cracked or failing coils. Just to clarify you have a 93 bike? One coil with a plug wire to each spark plug, not two coils with a lead from each?

I am not sure just how visible your coil is if it is the single coil or how hard it is to work on or remove? Do you have an Ohm meter you can test with? Sorry first visually inept the coil and look for cracks or damage. If none, then testing will have to start.

Sad to say also, the ignition modules while very reliable have been known to pop or quit working. In the older bikes, I am not sure about yours one of the fixes was to remove the ignition module from its mount and replenish the heat sink paste. The module is the black bit under the tank in the center.

This is a good time to perhaps go to Snowbum's website and see if there is step by step procedures for testing each of these components. There are other website guys to check out such as Anton Largidare, and Boxer two valve. Check also the Airheads club site there may be a link to testing.

Sorry, I am in Rochester NY, I have the tools but it is a bit far to you to help. Good luck. St.

 

[milo]

Thank you, Steve. Another dumb question, what to the coils look like? The ones I've seen in other applications are typically cylindrical. Yes 1993.




Not sure if this could have contributed but I knew the battery was pretty old, IIRC over 5 years, but I just noticed the date written on it when I put it in "5-10-2012", my God time flies! Voltage: at rest is 12.75, ignition on 11.84, cranking for 3 seconds (spark plugs back in) 8.8 initially then up to 9.5. So a new battery is in order no matter what but I don't believe that is what is not allowing spark.

 

[stevenrankin]

Follow

Follow the two main or one of the two main spark plug leads up to the center frame area under the gas tank. That will be your coil. LOL, I suppose I could figure out a way to download your picture and mark it and post it back but I think you will find them without that.

Your bike has the one coil with two leads. As I said, there has been issues of those cracking. I am sorry I don't know the exact years of bike infected.

As for battery capacity I can tell you this, if the battery is cranking the bike's engine over it has enough oomph to produce spark. I can attest to this having batteries fail and then having to roll start the bike on a down hill slope. But a new batter sure doesn't hurt. St.

 

[Omega Man]

Try adding a good battery in parallel- sorta a jump start. Those voltages, from my experience, coupled with “older” spark components, are too low to allow a reliable start.
If it wasn’t all apart I would suggest, with a fresh charge, what St suggested- a rolling down the hill “pop” start.
OM

 

[20774]

Doing what ST said, it would appear your coil is in the red circle. Also check out the image from MaxBMW's site:

https://shop.maxbmw.com/fiche/PartsSearch.aspx?&searchtype=undefined&parts=12131244426

 

[stevenrankin]

Thank you

Thank you Kurt, spot on.

Just remember rolling start or push starting a bike or kick starting when a battery is dead means there is just enough battery power to provide spark. LOL I couldn't tell you what RPM the bike is turning over as my fat butt is pushing it but if the bike is tuned properly it will start.

Try Omega man's suggestion, be aware however the little motorcycle battery sometimes won't handle large input from a jump start. it would be best if you jumped or what ever from another bike or lawn mower battery. You could also try taking the small motorcycle batter right out of the picture and using jumper cables hooked up to a car battery to the positive cable and negative cable of the bike as a replacement of the bike's battery. This way, you don't get a large amperage input into the MC battery. The car battery being bigger won't over load the system but will give you the power needed. Again the danger is jumping from a bigger car battery to the small MC battery. Make sense?

Before you go and try what I am suggesting, get some WD 40 and perhaps squirt the kill switch and different connections and terminal blocks in the wiring to displace any water that may be shorting out something. Good luck. St.

 

[globalrider]

No spark on either plug.

Measure the primary and secondary windings on the coil with a Digital Multi Meter (DMM). The low ohms reading might be a bit difficult with a cheap DMM, but it can be done.

What I measured back in 1992 on my 1990 R100 GS:
Resistance of primary coil: 1.1 to 1.3 ohm.
Resistance of secondary coil: 8.50 K ohm.

If I remember, also note that it uses the wasted spark system. Both plugs fire at the same time. One on compression and one on exhaust.
Each ignition wire measured 4.86K ohm.


Also those coils have a tendency to crack. I remember doing a diagnostic on a BMW and sure enough, his coil was cracked.

Next is the Ignition Module and the Hall Sensor, but that can wait till you check out the coil.

Also, on my 1990 R100 GS when I bought it new, I noticed the very slightest hesitation...you really had to have a good feel. One day when I took the Ignition Module and heat sink out to renew the heat sink compound, I noticed that one of the leads in the connector block was pulled back and not snapped into the connector. Sure enough after looking up the color code of the wiring, it was the wiring to the kill switch.

 

[stevenrankin]

Night time thoughts

Milo, I found myself musing your problem last night.

First, Forget all I blathered on about roll starting and kick starting, and even a dead battery having enough power to produce spark. This may be true as long as you are NOT trying to engage the starter at the same time.

IF you think your battery is near death, either replace it, take it out and have it load tested at an Autozone or other shop to get an idea if it is good or not. But I broke the first rule of troubleshooting. Always have a good battery.

If you are certain the battery is good, and the engine cranks over as it should during normal starting. At that point troubleshooting can begin. So if this problem started only after you washed the bike and you had a good battery. Start looking at the coil and stuff.


I know, I am rambling and sometimes do. Alex has provided an excellent picture of a cracked coil from that range year bike. LOL, I almost remember the coils prone to failure were gray and the later improved or replacement ones were another color but don't take my word on that, I imagine things all the time. St.

 

[globalrider]

Test, not guess.

Nothing could be simpler on a motorcycle when compared to cars.