Hi, first post here, very long so I can explain..
I have a 94 FXSTC with 24K on the clock, picked it up earlier this year. The PO installed a crane CV3 cam and some sort of adjustable push rods, drag pipes with HD Chrome Werks baffles. Since day one it sort of popped a little and I assumed it was because of the drag pipes and backpressure issues. I added a lolly pop to the exhaust, and that quieted it down some. After awhile I noticed that the rear pipe was making all the noise and lately it has been fouling that plug with thick carbon, to the point it starts to miss. If you hold your hand on the rear exhaust you will feel-(cold idle, enricher on a little); fire,fire,pop/poof,fire, fire, pop/poof. The noise is not a true backfire, it kind of barks or pops and at the same time it sounds like a pooof. There is also a little smoke out of the rear pipe, you have to catch it in the right light it's brownish black and does not linger in the air like oil smoke would. It's very slight and goes away completely when the bike warms and the enricher is in. The noise seems to go away at higher revs and when warm it is not as noticable but still there, you can feel it with your hand over the exhaust. The front runs even/no smoke/plug looks OK(maybe a tad rich) and in general the bike starts easy and runs strong through the gears. But it fouls that plug quickly at slower speeds and I'm sure it's carbon.
Here is what I have tried with no positive or negative results:
Switched plugs front to rear and tried a known good set, genuine HD and then Champions..same=rear cylinder issue
Tried a known good wire on the rear, switched the wires at the coil...same
Found an intake leak on the rear, changed gaskets-OK now, took carb apart, cleaned bowl and jets-everything, reinstalled and leaned as much as I could, runs exactly the same. (I did get a couple of carb coughs after this but that seems to have stopped).
Compression: (No oil consumption in the last 1K miles)
cold: F-150 r-154
warm:F-148 r-153
Gas is good-screen clean, all hoses are new including vacume, stock ignition and coil, zero oil consumption and zero oil leaks. For a 94 this bike is in amazing condition, frame clean top to bottom, tins look new, chrome near perfect, just a well cared for bike.
Even though switching the wires at the coil did not change anything, I took it off, the primary resistance looks high but I suspect my meter has gone (EDIT) because it is different each time I check it. Gonna borrow a buddys this morning. I took the plugs out and grounded them and cranked the engine. What should the spark look like? Mine looks weak, more red than blue, I've seen better (bluer) on lawn mowers.
I'm also going to get a clear plug and check timing.
Any ideas??
Thanks, sorry it's so long but I wanted to get everything out there..
Doug
Please read and understand the info in this link...
I have a 94 FXSTC with 24K on the clock, picked it up earlier this year. The PO installed a crane CV3 cam and some sort of adjustable push rods, drag pipes with HD Chrome Werks baffles. Since day one it sort of popped a little and I assumed it was because of the drag pipes and backpressure issues. I added a lolly pop to the exhaust, and that quieted it down some. After awhile I noticed that the rear pipe was making all the noise and lately it has been fouling that plug with thick carbon, to the point it starts to miss. If you hold your hand on the rear exhaust you will feel-(cold idle, enricher on a little); fire,fire,pop/poof,fire, fire, pop/poof. The noise is not a true backfire, it kind of barks or pops and at the same time it sounds like a pooof. There is also a little smoke out of the rear pipe, you have to catch it in the right light it's brownish black and does not linger in the air like oil smoke would. It's very slight and goes away completely when the bike warms and the enricher is in. The noise seems to go away at higher revs and when warm it is not as noticable but still there, you can feel it with your hand over the exhaust. The front runs even/no smoke/plug looks OK(maybe a tad rich) and in general the bike starts easy and runs strong through the gears. But it fouls that plug quickly at slower speeds and I'm sure it's carbon.
Here is what I have tried with no positive or negative results:
Switched plugs front to rear and tried a known good set, genuine HD and then Champions..same=rear cylinder issue
Tried a known good wire on the rear, switched the wires at the coil...same
Found an intake leak on the rear, changed gaskets-OK now, took carb apart, cleaned bowl and jets-everything, reinstalled and leaned as much as I could, runs exactly the same. (I did get a couple of carb coughs after this but that seems to have stopped).
Compression: (No oil consumption in the last 1K miles)
cold: F-150 r-154
warm:F-148 r-153
Gas is good-screen clean, all hoses are new including vacume, stock ignition and coil, zero oil consumption and zero oil leaks. For a 94 this bike is in amazing condition, frame clean top to bottom, tins look new, chrome near perfect, just a well cared for bike.
Even though switching the wires at the coil did not change anything, I took it off, the primary resistance looks high but I suspect my meter has gone (EDIT) because it is different each time I check it. Gonna borrow a buddys this morning. I took the plugs out and grounded them and cranked the engine. What should the spark look like? Mine looks weak, more red than blue, I've seen better (bluer) on lawn mowers.
I'm also going to get a clear plug and check timing.
Any ideas??
Thanks, sorry it's so long but I wanted to get everything out there..
Doug
Please read and understand the info in this link...
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