Sporadic Engine Misfiring

[essex47]

OK, I've got 6 into 6 pipes. No baffles.  Bike has been rejetted and runs great.  However, once in a while, while cruising, all of a sudden my pipes get excessively loud and I lose power almost as though I'm running on 5 instead of 6 cylinders or as though I've lost the use of one spark plug.  I ride home 20-30 miles and it stays the same.  Get up the next morning, start the bike and it drives like a champ so I can't take it to a mechanic and duplicate the issue.  This has happened several times.  I changed the plugs thinking it might be a plug break down, but that didn't solve the problem.  I shut my fuel off and shut off petcock while running to see if I could clear the line then flicked it back on to see if it was a fuel obstruction.  Put choke all the way on, ran it, then turned it off, no improvement.   I ride the bike daily and it happens every few weeks.  It's not weather related as it has happened in the rain or in the dry.  Winter and summer so it doesn't appear to be heat related.

I'm lost.  Does anyone have any idea as to what the problem might be?

Any thoughts on the matter are appreciated,
Richard

[Ricky-D]

I suggest looking for a lost spark problem.

Maybe a sparkplug wire is shorting for some reason. Cracked insulation, worn away insulation, some added bling doing harm. You get the idea!

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[sugerbear]

and maybe check the coils for intermittant ground. tighten up the mounting screws.
take the connections off and put them back on.
you know clean up all the grounds.

good luck.

[Daniel Meyer]

Possible Petcock or tank vent. Fuel starvation sounds a lot like that.

If it's spark you'll lose two cylinders (two per coil) usually...but I had a loose power wire to a coil that acted like that, except once it started happening it was not intermittent.

[YoungPUP]

Mine was doing something close to this on a ride to/from  indianapolis back in may. Checked all plugs at a rest area and the problem went away. Believe it may have been a loose plug wire.   ?????? Never happened again.

[Madmike]

If the other suggestions don't solve your problem then I have seen coils that break down when they get hot then are ok again when they cool down -  Is there any consistency in the amount of riding that it takes to get the problem started??

[Ricky-D]

Well essex47 hasn't found it necessary to reply to the forum as to the outcome or what he did to cure the problem. That's Ok.

I am only resurrecting this thread to point out another possible reason for his problem, that has been exposed in a more recent thread and it is this.

The thread relates to the weep holes in the spark plug recess.

I think it is entirely possible that a weep hole could clog up and hold enough water from washing or a hard rain to cause the spark plug to become an intermittent sparkler causing backfires and worse, completely shut down.

Just wanted to point this out to the forum.

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