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

[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/PartsS...ts=12131244426

R100RCoil.jpg

[STEVENRANKIN]

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.

Cracked Ignition Coil.JPG

[STEVENRANKIN]

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.

[STEVENRANKIN]

LOL, it depends on the motorcycle. At least we are dealing with a robust simple system. The best part is pretty much everything is easy access.

As for modern motorcycles I don't know about simple, some of the control systems are getting to be as complex as some of the cars on the road. Still I would rather work on a modern motorcycle where there is still more accessibly than under the hood of a car. St.

[ksdcr]

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.

Steve hit the nail with that comment. The issue began right after washing the bike.

[Pauls1150]

Wet spark plug wires; wet spark plug cap(s); wet coil; wet ignition sensor; wet condenser... You did wash the whole bike at the same time...

I really don't recall any "fusible link" on these, unless you mean the charging cable at the alternator/regulator? Item 12 on the MAX fiche.

"moisture got into a fuse and it's shorted" ... B/S.

[GlobalRider]

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.

The BMW rider I diagnosed his poorly running BMW was on his way to the Finger Lakes Rally...usually around the Labor Day weekend I think it was. I was there to pick up a BMW order as many of our Canadian members would ship to his place for a pick-up (free shipping in the US and free beer).

Anyway, he waited till I got there, picked up my BMW order and off he went in the rain to the rally. Minutes later, he was back with a poorly running BMW. After some DMM testing, within a half hour, I noted the crack in his ignition coil. The photo further up this thread is my cracked grey coil off my 1990 BMW R100 GS.

The new style coil is black despite all the beer you drank and you imagining things. I'm just having a German pretzel and a bottle of Lezajsk beer.

Bosch 0 221 500 203 Ignition Coil - Rear-XL.jpg

[STEVENRANKIN]

LOL, I don't get to poke around too much with post 84 bikes. So far my local airhead shop has not had a cracked coil issue in his shop.

By now I would assume any issues with water or moisture from the washing would be gone. I did forget to ask, I assumed the washing was done with the gas tank on the bike and the electrical stuff that used to be protected in the headlight shell on the older bikes was partly protected from direct spray by the tank.

I am really hoping as of today that the bike is running and being ridden. LOL forum, is not like phone or text. My fingers are crossed for the better. St.