Fouling front plug on 1340 Evo
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06-20-2006, 05:35 PM
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Fouling front plug on 1340 Evo
1997 FLHT. 62,000 miles. Trouble started about 3,000 miles ago.
First, my current configuration:
1. K&N air filter
2. Mikuni HSR 42 jetted as follows: 2 turns out on air screw, #25 pilot, #70 accel pump nozzle, #97 needle, #165 main.
3. Andrews EV-13 cam w/ upgraded bearing and adjustable rods.
4. White E-Series slip-ons w/ 12 disks.
5. Stock ignition w/ Accel plug wires.
6. Champion RN12YC rear, Got a new RN14YC up front.
7. Seat-of-your-pants timing.
8. Battery is strong, always on Battery Tender, but now at least 4 years old.
Prior to the fouling of the front plug, I had replaced the ignition wires with Magnecor 8.5mm wires. First suspected a bad wire, but a conversation with Magnacor convinced me to look elsewhere. So . . .
1. Tried different gasoline brands.
2. Swapped my SE ignition module back to the stock unit, no help.
3. Checked compression: 150 both cylinders.
4. Tested coil – bench checked same as new unit. Reinstalled old unit.
5. Swapped out Magnacor wires for Accel 8.7mm plug wires.
6. Rejetted (leaned) Mikuni one jet at a time in the following order: #17.5 (it had a 20) primary w/ 1.5 turns on air screw, # 98 needle, #60 accelerator pump nozzle.
7. Tried RN14YC (hotter) plug up front.
8. Swapped out coil for new H-D unit.
9. White E-series disks set @ 10 left, 13 right. (Previously 10/10).
The results each step of the way seemed to help or sometimes cure the problem, but it always reverted to fouling. After the carb needle change, did a 110 mile shake-down cruise with no fouling, ran well. When it fouled, swapping plugs front to back would get it going and clean up the fouled plug. Occasionally, new front plug would burp within a ½ mile. Anyway, the leaned out config seemed to be at least “OK” so I departed with the buddies on a 1,200 trip. Got a hundred or so miles before it puked and it puked all day after that with occasional reprieves.
In PA, a Harley mech listened to my sad story. He retested the coil, listened to the motor, and discounted both the coil and a cam bearing as the source of the problem. He tested for intake manifold air lead – it had some but not bad.
I got a coil at the parts counter and replaced it in the parking lot anyway. It seemed to help, but not sure as the motor was so carboned up it needed a good blowing out. Ran OK but lean (with vibration) for the next 700 miles. About halfway thru that 700 miles I did a Ramada-parking-lot jet swap (reinstalled the #20 pilot and the #70 accel pump nozzle) and took the disks down to 7/7 to try richening. Seemed to help.
Got home and rejetted Mikuni to “current configuration” above. Ran really well but then puked the front plug within a few miles. I doubt the RN14YC will be much help now – it wasn’t before. Any ideas???
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