I went for a mountain ride the other day. Bike was running fine, stopped at the top for a rest and went I went to start it, wouldn't budge.

I checked all the usual things. Pulled the plugs, saw they were black and wet, so I replaced them. But when I checked for spark by grounding them to the frame, I got nothing. The oil light was turning on, but the battery was almost dead.

So I took the battery out, charged it, and still no spark when I put it back. And now, the oil bulb is not coming on.

I have:
-checked the kill switch for continuity (good)
-went over all the electrical connections (good)
-checked battery voltage (12.55v)
-checked ignition coil resistance
Top Cylinder: Primary 1 ohms, Secondary 3,280 ohms
Bottom Cylinder: Primary .8 ohms, Secondary 4,330 ohms

I suspected it was my ignition coil connectors as they were flimsy, or the kill switch that was dirty. But cleaned both and still nothing, and the oil light won't turn on. Any ideas? Electrical issues are new to me so maybe I'm missing something...

Thanks

A friend of mine had this happen to him (MC18 R5k) and it turned out to be the TPS connector.
It looks like you know what you are doing. Keep at it and you'll get there.

Are you getting 12v at the ignition switch?

Thanks for the replies. I'm electrically illiterate, so bare with me.

I checked the ignition switch, was getting continuity in both wires (R/B and R) from the switch to the PGMIII harness. The voltage read 12.5 (R) and 0 (R/B) when OFF, 12.5 in both when ON.

Checked the continuity from the TPS connector to the harness, fine on all 3 wires, but didn't check the sensor or connector itself.

I did notice that when the TPS connector was disconnected, the powerservo motor moved when keys went to ON and when I tried to kick it to start. But when reconnected, didn't budge. Is that normal? How else can I check for full functionality of the TPS?

Got it running! But barely, feels like only the top cylinder is working. Now that I see how bad the fuel petcock is leaking, I'm going to replace it and see how the bike runs after that.

The bottom cylinder is not getting spark.

I checked and continuity is fine between all four wires from harness to coil.

I am not getting a voltage jump between the two wires on the bottom coil when cranking the bike. The top is getting 1-2 volts when cranking.

Ideas?

Roman250 wrote:I did notice that when the TPS connector was disconnected, the powerservo motor moved when keys went to ON and when I tried to kick it to start. But when reconnected, didn't budge. Is that normal? How else can I check for full functionality of the TPS?

With the TPS disconnected, the engine kill switch set to RUN, and the ignition on, the power valve servo will rotate to what the PGM thinks is the "Hi" position.
With the TPS connected, the engine kill switch set to RUN, and the ignition on, the power valve servo will rotate to what the PGM thinks is the "Low" position.

Oh, and yes, the TPS connector plug can be pretty difficult to pull apart.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Roman250 wrote:The bottom cylinder is not getting spark.

I checked and continuity is fine between all four wires from harness to coil.

I am not getting a voltage jump between the two wires on the bottom coil when cranking the bike. The top is getting 1-2 volts when cranking.

Ideas?

Check the PGM connectors. Had one once where the pin inside the PGM connector had blackened/corroded.
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If I have to take the carbs off once more...

Have you tried fresh or swapped spark plugs?

nxrsr20 wrote:Have you tried fresh or swapped spark plugs?

Yes. But the wires that connect to the bottom coil aren't showing voltage when I crank the bike over. Don't think it's the plugs.

I will try and clean the PGM connectors. Any good method for it?

I cleaned the PGM connectors and still running on top cylinder only. What could it be?

When I rev the bike, it sits at 3k. If I blip it again it returns to idle sloooowly. Is this common if its only running on one cylinder. Or could it be indicative of the cause of the problem??

Thanks

Swap the coils from top to bottom, see if the problem moves. I dont think the coil readings are 'bad' but it is reasonably different and worth trying.

greggo wrote:Swap the coils from top to bottom, see if the problem moves. I dont think the coil readings are 'bad' but it is reasonably different and worth trying.

Already did, coils not the problem.

It's highly unlikely a PGM problem (I have personally never heard of the ignition side of a PGM failing, although it's not impossible) but as Steve says, it is possible for connections at the PGM plugs to blacken over time. You have to remember that the oldest MC21 is almost 23 years old now!

Clean any connections very carefully with contact cleaner. Don't use anything abrasive on them. There's a very fine plating on each side of the connection, and once you break through it corrosion will build up much faster in the future. I often see posts where people say to "rub the terminal with some emery cloth", and it makes me cringe!

If it all worked, and suddenly you have no spark on one side, then it must be electrical. There aren't many components, and you've swapped most with no effect.

Once you are sure all connections are clean and secure, check the pulse coils at the flywheel. Do you know anyone else with an MC21 you can try your PGM-III on?
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Awesome, thanks for the info Andy. I'll get on that ASAP.

ありがとうございます！