Ignition help
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Intermediate
Joined: Apr 2009
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Ignition help
Hey all,
I have a 88fxr that is running real rough, when dead cold it will start ok but when it warms up it starts running real bad, idle is rough and if I ride it it misses and grabs back and forth, I swapped out the plugs and found the front plug fouled and the rear plug looked like it was running lean, I had the pushrods adjusted by a harley tech and it still running like this. He seemed to think it cuold be my ignition module (crane w/ single fire coil and wires), however the other day I was messing around w/ the wires running from the voes switch and when I wiggled the wire connecting the module to the switch the idle smoothed out. This happened twice then I couldn't duplicate it again. Any help or suggestions would be much appreciated.
I have a 88fxr that is running real rough, when dead cold it will start ok but when it warms up it starts running real bad, idle is rough and if I ride it it misses and grabs back and forth, I swapped out the plugs and found the front plug fouled and the rear plug looked like it was running lean, I had the pushrods adjusted by a harley tech and it still running like this. He seemed to think it cuold be my ignition module (crane w/ single fire coil and wires), however the other day I was messing around w/ the wires running from the voes switch and when I wiggled the wire connecting the module to the switch the idle smoothed out. This happened twice then I couldn't duplicate it again. Any help or suggestions would be much appreciated.
HDF Community Team
Joined: Dec 2005
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From: NC USA
I was going to suggest first, make absoutely certain there are no intake leaks. I've no experience with S S carbs, but there are several who frequent this section who do and may be able to offer some suggestions along those lines.
If the VOES is "out of circuit" as in, losing ground or module connection, that will slow the idle, but especially with a single-fire type module, it will revert to the "wide open" advance curve and should run OK above 3000 rpm (without the VOES) Only other thing I could offer, is to make sure the hose to the VOES is not leaking vacumn.
Basically, it could be a faulty module or more common, broken wires to it... or a vacumn leak which I'd check for, first. But again, I'm ignorant (by definition) to S S carbs and their habits, so hang around and some of the other guys will be able to offer suggestions concerning that. May be simple as water in the float bowl.......
good luck
If the VOES is "out of circuit" as in, losing ground or module connection, that will slow the idle, but especially with a single-fire type module, it will revert to the "wide open" advance curve and should run OK above 3000 rpm (without the VOES) Only other thing I could offer, is to make sure the hose to the VOES is not leaking vacumn.
Basically, it could be a faulty module or more common, broken wires to it... or a vacumn leak which I'd check for, first. But again, I'm ignorant (by definition) to S S carbs and their habits, so hang around and some of the other guys will be able to offer suggestions concerning that. May be simple as water in the float bowl.......
good luck
Last edited by t150vej; Apr 15, 2009 at 12:54 PM.
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Intermediate
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I really appreciate the feedback, I will check for vacuum leaks, I've been told that the intake gaskets will leak where they enter the heads but I would have thought that it would be idling high if that was the case but I could be thinking about it backwards, I've been known to do that a time or two...
Seasoned HDF Member
Joined: Aug 2007
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From: NW AR
Could be a vacuum leak. Check by spraying some cleaner at the intake joints. Or, those single fire crane ignitions seem to have problems. Maybe you can call the factory... wait, maybe not. Sorry, couldn't help myself. Anyway, you could try swapping the wires going to the coils, both primary and secondary, effectively swapping the coil halfs over, and see if the problem changes cylinders.
Club Member
Joined: Jun 2007
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From: Bedford UK
I had similar problems with my 1990 bike. When it finally packed up on me it turned out to be the ignition sender in the timer cover. Since then I have had minor problems which proved to be the small hose between the carb and VOES. These sort of problems can be a real swine to solve, but those are my recent experience!
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Thanks guys,
I'll definitley look for leaks, but I guess I'm a little confused, if it was a leak in the carb-to-voes hose, or the intake gaskets wouldn't that be causing a lean condition, which if I understand right, would cause it to idle higher not lower, my idle is really rough after it warms up and if I try to drive it it bogs out then wants to grab then bogs out again almost like it is not getting fuel, also the bike has always run pretty rich. If I have the lean/rich thing backwards feel free to let me know, I can take it
I'll definitley look for leaks, but I guess I'm a little confused, if it was a leak in the carb-to-voes hose, or the intake gaskets wouldn't that be causing a lean condition, which if I understand right, would cause it to idle higher not lower, my idle is really rough after it warms up and if I try to drive it it bogs out then wants to grab then bogs out again almost like it is not getting fuel, also the bike has always run pretty rich. If I have the lean/rich thing backwards feel free to let me know, I can take it
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Club Member
Joined: Jun 2007
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From: Bedford UK
The VOES is a 'vacuum operated electronic switch', or something close to that! What it does is retard the ignition when the engine starts pulling, as the vacuum in the carb increases. If there is a leak the ignition timing doesn't change and really messes up the way the engine runs, especially as you try to ride away. Mine ran like a real b1tch, but cost a few cents for a new pipe to put right.
You are right about a leak in the inlet gaskets, which would indeed cause lean running. If anything, the VOES pipe leak gives the impression of running rich (although it isn't).
You are right about a leak in the inlet gaskets, which would indeed cause lean running. If anything, the VOES pipe leak gives the impression of running rich (although it isn't).
Road Warrior
Joined: Apr 2007
Posts: 1,952
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From: Senoia, Ga., by way of Miami, Fl..
Thanks guys,
I'll definitley look for leaks, but I guess I'm a little confused, if it was a leak in the carb-to-voes hose, or the intake gaskets wouldn't that be causing a lean condition, which if I understand right, would cause it to idle higher not lower, my idle is really rough after it warms up and if I try to drive it it bogs out then wants to grab then bogs out again almost like it is not getting fuel, also the bike has always run pretty rich. If I have the lean/rich thing backwards feel free to let me know, I can take it
I'll definitley look for leaks, but I guess I'm a little confused, if it was a leak in the carb-to-voes hose, or the intake gaskets wouldn't that be causing a lean condition, which if I understand right, would cause it to idle higher not lower, my idle is really rough after it warms up and if I try to drive it it bogs out then wants to grab then bogs out again almost like it is not getting fuel, also the bike has always run pretty rich. If I have the lean/rich thing backwards feel free to let me know, I can take it
Oh, something else.. The jugs and heads grow pretty dramaticly as the heat up. If the intake seals arent in good condition, the problem could easily come and go with temp..
On the other hand, my bike did the same thing due to the ignition pickup wires being broken at the cam cover. Try wiggling those wires while its running.. Although I'd also look at your VOES wires since you said that made a differnce when you played with the connector..