No spark

My '82 R100RT had been sitting for 9 days when I tried to start it today. No response but it cranks. Battery is good. No spark on the plugs when I cranked it - but there is one when I shut down the ignition. Suggestions anyone before I start tearing things apart? Thanks!

Balder

Can you provide a bit more detail, as in when you say there was no spark did you pull a plug and look at it or simply it didn't seem to catch and not sure I understand the "spark when I shut down the ignition." the more info and detail the better the folks here can help you.

Also did you check to make sure you had gas flow to the carbs, was the choke on/off, air in the tires (ok, just kidding on the last one but then again.... )

RM

rocketman,

Thanks for a fast response, I guess I should have explained the problem better. I did unscrew the plugs and put the electrode to the cylinder as I cranked the starter. No spark. But, as I switched off the ignition the plug gave off a spark. On one occasion the other cylinder (with the plug in place) actually caught. And yes; gas in the tank, air in the wheels and good mirrors as well!

Balder

Ok so we have fuel (and air!) but no spark when cranking.... Hmmmm.

I know that sometimes when I shutdown my 78 R100 I'll get a last "pop" as if the coils are discharging, which is I beleive, how they work, when the circuit on the "input" side from the points is opened the coil fires by discharging the energy stored on the output side of the coil wrappings (right?) so it would seem that at least one coil is good..

if you had some spark on the other side and the plugs share the same "trigger", i.e. both plugs fire every time, so if it were a section in common to both, before the coils and plug wires you would not get fire on side and not the other, so try to swap the coil wires from plug to plug while attached to the same coil, then swap the wires around. If it were me I would check for loose wires to and from the coils first, so the tank has to come off, but not a big deal on an airhead. if those all look tight I might try unplugging the plug wires at the coil and swapping them side to side and see if the side that did fire follows. Next I'd check the plugs themselves, even thou it only been nine days since it ran, it Could be that they were just starting to foul, but being warm and having been running it might not have shown a problem the last time it was running.

There is start anyway, I'm sure others will follow and correct any groose mistakes I may have made!

again its always

power (ie good battery to crank the engine since we don't have a kicker and to "energize" the circuits)
fuel
spark


and we have two out of three so....

RM

Problem solved! As you were writing your response I was outside taking off the tank and rattling the connections. The black box there (ignition control unit?) had a loose connection. Thanks for your input, this is a great board!

Balder

PS It still gives off a spark when I shut it down, I guess the coils are supposed to ground themselves or something when the ignition is switched off.

Balder said:

Problem solved! As you were writing your response I was outside taking off the tank and rattling the connections. The black box there (ignition control unit?) had a loose connection. Thanks for your input, this is a great board!

Balder

PS It still gives off a spark when I shut it down, I guess the coils are supposed to ground themselves or something when the ignition is switched off.

Click to expand...

yeah, like I said, when you shut it down it will break the connection on the input side of the coil and any residual energy stored in the coil will flow to the plug.

Glad yyou got it fixed (and glad I actually seemed to know what I was talking about, it doesn't happen all that often, less and less it seems, the older I get! Ha Ha!)

RM

You also might want to do a once over under there (tank) while you're at it and make sure everything is nice and tight, if it came lose once...
loosing power at the wrong time like in a tight sweeper or in traffic could be a bit unnerving...just at thought....

RM

RM,

A very good point, I actually did that since I had the tank off. Just got back from an evening 100-mile ride in beautiful weather and scenery, no problems at all. Thanks for your assistance!

Balder

you're welcome, nice weather you say? You must not be on eastern seaboard, its downright nasty around here, hot humid just plain yucky!

Glad you had a good ride.

RM

rocketman said:

..... You must not be on eastern seaboard, ....
RM

Click to expand...

RM,

Actually I'm on the southwestern seaboard - of Norway, land of the Midnight Sun and polar bears. Great roads and scenery for riding a motorcycle, but all Americans who come visiting define the roads as "skinny & scary". Come have a look for yourself.

Balder

Balder said:

RM,

Actually I'm on the southwestern seaboard - of Norway, land of the Midnight Sun and polar bears. Great roads and scenery for riding a motorcycle, but all Americans who come visiting define the roads as "skinny & scary". Come have a look for yourself.

Click to expand...

Doesn't get much prettier than that! Nice pic, great bike.

As you cleaned and tightened under the tank, you might consider applying a little di-electric grease to all the connections you tighten AFTER you've tighten them. That is, to the outside, exposed metal to prevent corrosion.

...in the meantime, I wonder how much to ship me and my bike to Norway. Always wanted to visit. Glad you got it fix with RM.

Cheers.

love the look of the twisty road
wonder what its like on brakes coming down
of course that is what proper gear selection is about too

also I have read that a person can rent nice bikes over there for a few days
Norway is on our list as that is where my wifes family ( generations back) came from and I guess the original homestead is still standing

I think it is "god vei og motorsykkel"
( nice road and motorcyckel)