Misfire

[invalidsession]

Hi fellas, I posted a while back about an overflow situation on one of my carbs. Got that sorted out with the help of some of the good folks here.
Now I have a similar symptom but a different outcome while riding.
At lower speeds and gears the bike seems to run very well but on the Highway in the higher gears the bike is surging and missing. I also noticed yesterday that I was getting a puff of smoke when I started her up on a couple of occasions. I will check all the obvious this morning (spark etc) but since it runs well at lower speeds and loads I'm not sure if I will be able to replicate the higher load condition.
Once again, any and all suggestions will be gratefully received.
The bike btw is an 07 with 7000 on the clock
Thanks lads.

Chris.

 

[The Beekeeper]

Did you change the plugs after sorting out the carb issue?..............Start with the simple things first.................Tom.

 

[invalidsession]

Beekeeper, I did not mate. I had changed the plugs with a set of NGK Iridiums just a few weeks before the carb issue (not related) and the bike was running fantastic until the overflow issue. Well what do you know; The same cylinder had a plug wire that had stripped out at the connector to the plug cap. All green and nasty where (I imagine) the high voltage wire from the coil was trying to jump through the plug connector and then to the plug itself. Going back to my days as a wrench this makes sense as regards my first post inasmuch as the lower resistance required at partial throttle would allow the voltage path through to the spark plug but when it was asked to operate at a higher level the natural path would be to the side of least resistance which in this case would be the cylinder head. I trimmed back the plug wire 1/4 inch to get to fresh internal cable and dug out the damaged wire from the cap, spritzed a little connector cleaner in and reattached. It all seems good for now but no road test yet. I'll report back tomorrow but for now all seems good
Thanks for reminding me Mr Bee that not all issues have a dark path to the solution.

Chris.

 

[The Beekeeper]

Sounds like you are on the right track, very common for wire/cap connections to get dirty, let us know how the road test goes!..............Tom.

 

[invalidsession]

Sounds like you are on the right track, very common for wire/cap connections to get dirty, let us know how the road test goes!..............Tom.

Just to update; I took the bike out yesterday and no sign of the misfire issue.
I also went through the other plug cap / wire connections and cleaned everything up and added a little dielectric grease to each.
Thanks for the help

Chris.

 

[invalidsession]

Another update fellas; The misfire returned . Same carb / cylinder and the same result. Perfect response up to 4th / 5th gear on the highway. Seemed like the bike couldn't handle the extra load. Scratched my head and once again went baxter basics. Checked for consistent spark across the cylinders. All firing solid but it's not easy to test under load conditions so I replaced the "less than 1.000 mile since installed" NGK Iridiums with just regular NGK's and all is well again. The Iridium plugs showed a darkish tan on the insulators which I gather is the usual set up with a stage 7 kit but do you think I should lean the carbs out a little or just let them be ? Idle is great, instant start and very good response from low RPM's to Holy Cucking Fow. I reckon I should leave well alone for now and see how she runs in the longer term but all your opinions will be well recieved.

Cheers all

Chris.

 

[The Beekeeper]

How old are the plug wires?...............They can cause misfires under load..................Tom.

 

[invalidsession]

How old are the plug wires?...............They can cause misfires under load..................Tom.

Original wires Tom and lo and behold, went for a thirty mile run today and I'll be damned if another carb didn't start overflowing. Everything perfect until I pulled off the exit ramp. Bike ran great up to that point then dropped out on another cylinder. Had to give another carb another whack with the screwdriver to be able to ride tonight. You think it might be the fuel filter breaking up ? I'm having a hard time fathoming this out, why is it jumping from pot to pot ? Strange days indeed Mama.:confused2:

Chris.

 

[leroycp]

Do make sure your vent hoses are intact and mounted to the airbox