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confounding intermittent problem
Posted: Wed Nov 04, 2009 11:23 pm
by _Will_
1994 FZR 600 49 states
started off with a plug not firing and the bike stumbling around 7-8k, thought maybe it was bad gas so ran sea foam through it. The SF helped for a while and the problem returned, checked the plugs and one was fouled so sand blasted it and bike ran fine for maybe 10 miles to dinner and most of the 25 home that night with a little spit and sputter. was missing and backfiring worse than before when I left my Halloween crash pad the next morning at my friends and I greased up the plugs with some dialectic the next day thinking maybe a bad connection since I'd taken the plugs off and the weather had been bad. Took the bike out and it spit and sputtered for the first 10 minutes of riding pretty badly and then smoothed out and ran like a champ pulling hard all the way to redline for the rest of the day. Next day (today) same situation with first 10 minutes spitting and sputtering and then it smoothed out. Problem doesn't return throughout the rest of the day even when stopping for several hours. I did notice a plume of white smoke upon starting.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 12:23 am
by fzrbrandon
Pull off the caps on the plug wires and trim the wires back a bit. My guess is that one of them has a bad contact. The caps screw onto the wire via an actual screw (duh! LOL!) that's mounted inside the cap. If the contact is bad, the plug will have a weak spark and just get soaked since it can't ignite the fuel. It sounds like the contact is kind of good yet kind of bad (read: bad altogether) so it's giving you this intermittent issue.
*EDIT* While you're at it, you may want to check and make sure the resistance value for the caps is in spec.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 12:37 am
by _Will_
fzrbrandon wrote:Pull off the caps on the plug wires and trim the wires back a bit. My guess is that one of them has a bad contact. The caps screw onto the wire via an actual screw (duh! LOL!) that's mounted inside the cap. If the contact is bad, the plug will have a weak spark and just get soaked since it can't ignite the fuel. It sounds like the contact is kind of good yet kind of bad (read: bad altogether) so it's giving you this intermittent issue.
*EDIT* While you're at it, you may want to check and make sure the resistance value for the caps is in spec.
I thought about the wires but why would it only be doing it when cold like it is now?
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 1:20 am
by fzrbrandon
_Will_ wrote:fzrbrandon wrote:Pull off the caps on the plug wires and trim the wires back a bit. My guess is that one of them has a bad contact. The caps screw onto the wire via an actual screw (duh! LOL!) that's mounted inside the cap. If the contact is bad, the plug will have a weak spark and just get soaked since it can't ignite the fuel. It sounds like the contact is kind of good yet kind of bad (read: bad altogether) so it's giving you this intermittent issue.
*EDIT* While you're at it, you may want to check and make sure the resistance value for the caps is in spec.
I thought about the wires but why would it only be doing it when cold like it is now?
It may just be a coincidence. My guess is that only one plug is going "bad". I doubt the bike would run at all if it were two so that kind of rules out a bad coil (since both plugs 1&4 OR 2&3 would be problematic). If the plugs are in otherwise good shape, start suspecting the easy stuff. Next in line for me would be to check the cap connection. I know this because I went through it recently with my 600. I had a #2 plug that kept getting wet so I was advised by a fellow board member (or two!) to check the caps. Lo and behold, when I went to unscrew the #2 cap it practically fell of the plug wire. I checked the resistance on all caps and screwed them back on real good and haven't had a problem since. Oddly enough, the symptom kept appearing in the morning (when it's colder) when I would try to ride of to work. The bike would have trouble starting, sounded rough, and would pop out the exhaust (which is unburnt fuel from the cold cylinder igniting in the exhaust). Anyway, check this out. If nothing else you can rule it out as being the problem and you can move forward with trying to figure it out.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 7:29 am
by yamaha_george
fzrbrandon wrote:_Will_ wrote:fzrbrandon wrote:Pull off the caps on the plug wires and trim the wires back a bit. My guess is that one of them has a bad contact. The caps screw onto the wire via an actual screw (duh! LOL!) that's mounted inside the cap. If the contact is bad, the plug will have a weak spark and just get soaked since it can't ignite the fuel. It sounds like the contact is kind of good yet kind of bad (read: bad altogether) so it's giving you this intermittent issue.
*EDIT* While you're at it, you may want to check and make sure the resistance value for the caps is in spec.
I thought about the wires but why would it only be doing it when cold like it is now?
It may just be a coincidence. My guess is that only one plug is going "bad". I doubt the bike would run at all if it were two so that kind of rules out a bad coil (since both plugs 1&4 OR 2&3 would be problematic). If the plugs are in otherwise good shape, start suspecting the easy stuff. Next in line for me would be to check the cap connection. I know this because I went through it recently with my 600. I had a #2 plug that kept getting wet so I was advised by a fellow board member (or two!) to check the caps. Lo and behold, when I went to unscrew the #2 cap it practically fell of the plug wire. I checked the resistance on all caps and screwed them back on real good and haven't had a problem since. Oddly enough, the symptom kept appearing in the morning (when it's colder) when I would try to ride of to work. The bike would have trouble starting, sounded rough, and would pop out the exhaust (which is unburnt fuel from the cold cylinder igniting in the exhaust). Anyway, check this out. If nothing else you can rule it out as being the problem and you can move forward with trying to figure it out.
warm moist air round engine from the ride turns to condesation in the cold.so lousy start and first few mins till water evaporates again.
Does this "rough" time span connect to you using the choke.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 9:34 am
by _Will_
I don't really need to use the choke George, in fact it fires up quite well and I'm off ,the popping normally doesn't start till I'm moving and then continues for the next 10 minutes (sorry forgot that fact). The white smoke from start I think means water so the condensation theory makes sense, particularly since it's normally being turned off for the day near midnight. I work for the next few days so I'll have to find time to tinker with it.
Brandon, do the caps just slide of the wire to get to the connection? I should be able to give that a look as well
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 9:42 am
by yamaha_george
_Will_ wrote:I don't really need to use the choke George, in fact it fires up quite well and I'm off ,the popping normally doesn't start till I'm moving and then continues for the next 10 minutes (sorry forgot that fact). The white smoke from start I think means water so the condensation theory makes sense, particularly since it's normally being turned off for the day near midnight. I work for the next few days so I'll have to find time to tinker with it.
Brandon, do the caps just slide of the wire to get to the connection? I should be able to give that a look as well
NO they screw on, I would look at the wire route too see if it passes close (almost touching if not actually touching) to the engine / chassis ) this would make the condensation theory sound as the HT sparks along just one wire to short out that cylinders HT. Once the engine is HOT the waters gone no longer making apath for the HT current.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 10:14 am
by _Will_
yamaha_george wrote:_Will_ wrote:I don't really need to use the choke George, in fact it fires up quite well and I'm off ,the popping normally doesn't start till I'm moving and then continues for the next 10 minutes (sorry forgot that fact). The white smoke from start I think means water so the condensation theory makes sense, particularly since it's normally being turned off for the day near midnight. I work for the next few days so I'll have to find time to tinker with it.
Brandon, do the caps just slide of the wire to get to the connection? I should be able to give that a look as well
NO they screw on, I would look at the wire route too see if it passes close (almost touching if not actually touching) to the engine / chassis ) this would make the condensation theory sound as the HT sparks along just one wire to short out that cylinders HT. Once the engine is HOT the waters gone no longer making apath for the HT current.
when he says caps is her referring to the boots that go over the plugs? I assumed so but it seems I may be wrong.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 11:27 am
by yamaha_george
yamaha_george wrote:[
when he says caps is her referring to the boots that go over the plugs? I assumed so but it seems I may be wrong.
Ah the old culprit the english Language :_}}}}}
OK the plastic plug caps that house the connection for HT leads to the spark plugs SCREW in to the wire to get a good connection. To keep water out of that connection (in theory) there are rubber boots that slide into place to cover the connection of wire to plug cap.
Nothing a few million words cannot explain oh to be good with graphics LoL
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 11:38 am
by fzrbrandon
_Will_ wrote:
when he says caps is her referring to the boots that go over the plugs? I assumed so but it seems I may be wrong.
Hey Will,
Yes, it IS the boots but it's the end closer to the wire (not the plug). As George said, there is a rubber sleeve over this section to keep water out. Just slide it off and unscrew the cap (boot) off the wire.
Re: confounding intermittent problem
Posted: Thu Nov 05, 2009 11:40 am
by _Will_
fzrbrandon wrote:_Will_ wrote:
when he says caps is her referring to the boots that go over the plugs? I assumed so but it seems I may be wrong.
Hey Will,
Yes, it IS the boots but it's the end closer to the wire (not the plug). As George said, there is a rubber sleeve over this section to keep water out. Just slide it off and unscrew the cap (boot) off the wire.
that's what I was thinking
hey George, I think I have it but what does HT mean ?