Topic: Running on #3 only, where should I start looking...

[Holshot]

Hey guys,

The gremlins are busy at work while she’s been sleeping in the garage for the past month or so as there’s been no time to ride. About a month ago we had a bike week in Ocean City, MD and she ran great all weekend. Got tons of thumbs up from all the Harley guys. On the way home she started running bad (bucking, stumbling, running rich) pulled into the garage to find fuel spilling out of the overflow tubes. Pulled the bowls and didn’t see the floats hung up but I took them all down and cleaned with some carb cleaner and put everything back together and she back to normal...

Fast forward to yesterday, after a week of rain a beautiful day presents itself so off to the garage for a nice Sunday ride and she doesn’t want to start. After multiple attempts she finally kicks over barely only to shut down after maybe 20 seconds of running. I touched the header pipes and only the 3rd cylinder was hot. 1,2,4 were cold. Any ideas on where to start on trying to diagnosing the issue at hand?

Side note, I also noticed a little bit of oil which seems to be coming out of the air box on the leading edge of the top portion of the air cleaner cover. With the bike on the side stand it would lend itself to follow that path. Could that be blowby or reversion coming up through the carbs?

The battery is good and she sits on a trickle charger when I know she won’t be ridden for a week or more. Had a new driveway poured so she got locked in until I could get her out yesterday but alas she said NO!

As always, any and all constructive advise or ideas on where to start is GREATLY appreciated! I did do a search prior and mostly could find issues like 2 cylinders down which using pointed to a dead coil. This is weird (for me) for only 1 cylinder is running...

Kind Regards,
Joe

[ekpent]

 What year and model bike ? That is probably gas and not oil coming from your air box and it sounds like the engine may be severely flooded. Pulling the spark plugs will tell if that is so.

[BomberMann650]

Pull the plugs to confirm spark and if you got points - test your condensers.

Condensers do fail intermittently before they lose all their smoke.  Could explain the rough ride home (been there done that)

[BobbyR]

Since these are waste spark engines having one cylinder running is unusual for ignition. If those plugs are not wet you probably have a fuel problem.

[Holshot]

First thanks for the replies! I should have mentioned in my original post that I did pull the 1 &4 plug and they were slightly wet with fuel so it’s not a fuel issue I’m thinking. Not flooded wet but enough to show that fuel is getting to the other cylinders.

Refresh my memory on the plugs. Can I pull one at a time and with it connected to the wire and then while trying start hold it close to the engine to see if the there’s a spark. My question is does it matter where or what part if the engine I hold it up to? Valve cover, head fins or is something steel a better conductor like the frame.

Keep any ideas coming and the order best in which to try...

Thanks!

[Gene]

The head is a fine ground to check for spark.

[TwoTired]

Pay attention to the electrode insulator deposits.  If they are black, the coating shunts spark energy away from the spark gap.

Any metal on the engine carries the spark lead return path to the other spark plug.  It's what the spark plug screws into, after all.

The current path is from lead to spark plug to engine metal to the other spark plug and then the other lead on the same coil.

[BomberMann650]

Just hold the electrode of the plug against the head nearish its hole.
Sometimes I use a spare plug from the tool box to be lazy.  test all four real quick like.
If your plugs are wet and black, they’re fouled.  You might want new plugs anyway.

[Holshot]

Just hold the electrode of the plug against the head nearish its hole.
Sometimes I use a spare plug from the tool box to be lazy.  test all four real quick like.
If your plugs are wet and black, they’re fouled.  You might want new plugs anyway.

I’ll try and check spark tomorrow afternoon. I did do plugs at the end of last season and they only have about 1000 miles on them and that might be generous as I’ve been super busy this riding season. I have a spare set I could always throw in but it seems like it might be ignition related?

[BobbyR]

The plugs fire 1-4 and 2-3. For example if the bike were running and you pull #1 wire #4 would drop out. The engine block is part of the circuit. This is how they only use 2 sets of points for 4 cylinders. To have only one cylinder running would point to fuel. It has been reported here many times that the circuit is made but one plug does not actually fire. The overflowing is a clear symptom that you have some issue in the carbs. I would suggest you use the clear tube method to check the fuel levels in the float bowls.  You can Google clear tube method since the search here is not functional. You should check the spark as suggested above since you can have two problems at the same time. Eliminate spark and you can concentrate fully on the fuel problem.

[ilikepinkcrayons]

I had a similar issue (i don't remember the exact details), but it turned out I fouled my plugs beyond function. I didn't have any spares at the time, so I heated them with a propane blow torch until the electrodes and insulator were clean (use pliers to hold the plug at the connector tip). Worked like a charm.