Intermitant engine death

[Fraidknot]

A little bit of possibly irrelevant info. A couple of months ago I thought I could get away with unplugging and removing the EXUP servo on my Cali model bike. I no longer have the stock exhaust so the thing just kinda sits there buzzing for no reason and taking up space and weight. Bike idled with it disconnected from the CDI so I figured it was just dead weight. Couple hours later I got on my bike to go to work for the evening and about a half mile out the bike started bucking quite horrendously. I'm pretty sure the engine was dying and then bump starting back to life cuz when I pulled in the clutch it stayed dead. Starter would run but the bike wouldn't start. I was real worried that I blew out my CDI. Pushed it home, uphill, in gear, mid-day heat which is a pretty good workout if you were wondering. Decided to call in sick to work since my bike wasn't feeling too well. Hooked the servo motor back up and the bike started up fine. Went for a brief ride and all was well.

Now we come to today. I had been riding the bike for the last month with no issues. Today, on my way home from work I noticed a slight buck before getting on the freeway, like from before, but nothing immediately after that. After I had been on the freeway for a couple miles it started to buck like before so I tried to keep it going while pulling to the right shoulder and exiting. Bike was dead as soon as I pulled in the clutch. Coasted to a stop at the top of the exit ramp. Tried to start it, no start. Checked my fuel, checked my battery connections. Everything was fine. Tried to start it again, and it started! Revved it up but once the RPMs dropped, the bike died. Was a pain to get it started again, but everytime I did, it'd idle fine but as soon as I revved it up it'd die after the RPMs dropped. Checked the fuses, they were all fine except that the headlight fuse was really hot and sort of heat deformed. I let it cool off before reinstalling it, turned off my highbeams, started the bike and this time it would stay on after I revved it. I was able to get home 10 miles later with no further incident.

So what the heck? Sometimes, if I haven't riden the bike for several days, the fuel pump sticks. I have to tap it hard with a screw driver to get it going and then I have no issues. I would imagine that my CDI is still okay. Maybe the ignition coils are going out? I checked the primary and secondary resistance on them about a year ago while troubleshooting another problem but they were in speck at the time. I've always had a love/hate relationship with this thing.

[95FZR600]

Sounds like some of your connections arent very good. Also, your CDI box could be bad or the connections on it.

[Beckett]

If I am reading it right it sounds like it starts acting up once it's warmed up? It's very possible it could be something electrical as you think. A lot of electronic equipment will fail once warm/hot because the parts expand with heat. You can't bench test the CDI so I'd test anything else you can - THEN swap the CDI and see if that helps. Also if your fuse was hot... do a charging system check. Make sure you are getting proper voltage from the VR to operate the bike. Just my random thoughts...

[ragedigital]

Just a quick note: I ripped my EXUP servo off and have never had a problem with the bike running properly. It must be something else. I have the same EXUP CDI - it just doesn't have anything plugged in on the servo side.

darrin

[haunter]

Just a quick note: I ripped my EXUP servo off and have never had a problem with the bike running properly. It must be something else. I have the same EXUP CDI - it just doesn't have anything plugged in on the servo side.

darrin

wierd.

the 1K's HATE that from what I understand

[ragedigital]

Well, the 600s have them for a specific reason and it has to do with the Cali emissions stuff from what I know. Plus, all of the 1ks have the EXUP, where only the Calis have it in the 600 class.

[Fraidknot]

Just a quick note: I ripped my EXUP servo off and have never had a problem with the bike running properly. It must be something else. I have the same EXUP CDI - it just doesn't have anything plugged in on the servo side.

Did you pull the servo connector off the CDI or did you leave it connected but clip the wires? I'm guessing you pulled it off. I had a dumb thought that clipping the wires would trick the CDI into thinking it's still there. I guess I'll pull the main CDI connector off and make sure all the wires and pins are nice and secure in the connector housing. I was having hell with my main relay awhile back that was solved by simply crimping down the connecting pins inside the plastic connector housing.

I guess I'll go ahead and run through the charging system check.

[Beckett]

I remember a while back a local guy selling an "EXUP servo sub" - dunno if this would work but it's worth a try for you Cali bike guys...

http://www.samannasystems.com/

1/2 way down the page it talks about it. This is for if you have aftermarket exhaust - not stock it appears.

[ragedigital]

Did you pull the servo connector off the CDI or did you leave it connected but clip the wires? I'm guessing you pulled it off.

I pulled the servo off intact. No wire clipping. The CDI is open on that side.

Here it is:

[haunter]

Well, the 600s have them for a specific reason and it has to do with the Cali emissions stuff from what I know. Plus, all of the 1ks have the EXUP, where only the Calis have it in the 600 class.

all 89+ 1k's do....the 87-88 do not.......

but yeah. makes sense that they wouldnt work the same, I just ass-u-me'd they probably did

[yamaha_george]

Checked the fuses, they were all fine except that the headlight fuse was really hot and sort of heat deformed. I let it cool off before reinstalling it, turned off my highbeams, started the bike and this time it would stay on after I revved it. I was able to get home 10 miles later with no further incident.

.

FK,
That is the clue right there, fussing with all the Calif stuff is a waste of time.
Your head light is drawing so much current at the time as to melt the case of the fuse. take the head light connectors of and CLEAN them and use a good di-electric grease ( from RS ) to stop further corrosion. check the insulation on the wires just in case vibration is eating it thro'.

[haunter]

yes...you may want to do some wire tracing to make sure its not crimped up somewhere else as well

[Fraidknot]

They're fairly new bulbs. Stock wattage. Not HID. Do you mean for me to clean the connector that plugs into the bulbs? I should get another 20A fuse while I'm out.

I think I'll still check the pins in the CDI connector. Only because I was riding it around for a month with no problems so I don't think the headlight could have had much to do with that.

As far as the wiring harness. It's kind of beat up, especially sub harness for the headlights and front turn signals. Guess I'll make sure everything is doing okay there as well. Gah!

[yamaha_george]

They're fairly new bulbs. Stock wattage. Not HID. Do you mean for me to clean the connector that plugs into the bulbs? I should get another 20A fuse while I'm out.

I think I'll still check the pins in the CDI connector. Only because I was riding it around for a month with no problems so I don't think the headlight could have had much to do with that.

As far as the wiring harness. It's kind of beat up, especially sub harness for the headlights and front turn signals. Guess I'll make sure everything is doing okay there as well. Gah!

FK,
The fuse is heating and that means too much current, could be that dodgy sub harness you speak of........

[Fraidknot]

Update. I replaced the headlight fuse and then went through and cleaned all the dust and road grime out of all the main connectors. I am now almost possitive though that my problem wasn't caused by an electrical problem but instead by a fuel problem. My intermitant engine death has only presented itself when cruising at speeds higher than 90 mp/h or so. I'm thinking that I may just be fouling my plugs due to a too rich main jet. Either that or my choke is stuck open. Also, I get crazy good fuel economy when sticking to 65mph on the freeway. Upwards of 52 miles per gallon. If I bump the speed up to 80-90 I average about 37 miles per gallon.

I've always suspected my choke of possibly letting in fuel even though it's closed. I've checked the plungers and they all seat properly and the needles aren't worn that I can see. Maybe it's not the choke. I suppose I can take the carbs apart and drop in the next smallest main jet and put the needle on a richer clip. I feel the fuel delivery is just right in the midrange. Leaning out the main means I should richen up the needle to keep things the same, right? It might be a bit too rich off idle as well since the bike is real gurgly when cold. But then again, using the choke lets the bike idle quite nice until things get warmed up. Doesn't the choke on our bike add fuel, versus choking the air supply? Wouldn't that mean my pilot is jet too lean?

Doing this high velocity porting has really mucked with my stock carbs settings. Sheesh