Does this sound like an electrical problem?

I've been having this very intermittent problem where the bike (80 kz750e) will suddenly begin to lose power until it dies completely. This usually takes about a minute from the time I begin to notice the problem. Once it dies, I pull over, wait a few seconds and the bike starts right up again and seems to run fine (although I take it a lot easier on the engine after this happens).

It's happened about four times in the last month, but the only commonality I can tell among each occurrence is that I'm going above 60 mph.

I initially thought the carbs were too lean and that it was overheating because it happened a couple times on very hot days. Yesterday, however, I rode about 40 miles during the day and it was about 80-85 degrees out. Then it died on the way home last night when the temperature was closer to 60 and I was going about 5-10 mph slower.

While riding it home, I thought I noticed in the rear view mirror that my tail light seemed to be flickering a bit, leading me to question whether it was an electrical issue. The head light seemed fine, however.

Does this sound like an electrical issue, carb issue, something else? I'd rather not spend a lot of time troubleshooting an electrical problem that doesn't exist.

Thanks,
Chris

Fuel starvation, perhaps from clogged vent in fuel cap.

Test run with fuel cap ajar (by-passes need for vent).

For whatever reason, not enough fuel is getting into the float bowls.

Good Fortune!

The tail ight flickering might be due to either a loose bulb/corroded socket.

Have you checked the battery voltage at idle and again at 4000 rpm? At 4K it should be 14 volts.

If you have the time and patience, go through all electrical connectors, starting at the headlight housing and going toward the tail light.

I use a very good brand of electrical contact cleaner/preservative called "De-oxit" It can be bought at Radio Shack stores and other electronic supply stores.

www.deoxit.com is their website.

I do not recommend using WD-40 on electrical contacts or fuse clips as later on it becomes a non conductor.

Patton wrote:

Fuel starvation, perhaps from clogged vent in fuel cap.

Test run with fuel cap ajar (by-passes need for vent).

For whatever reason, not enough fuel is getting into the float bowls.

Good Fortune!

You know, each time it has happened I thought I had run out of gas. I checked and there was plenty in the tank, so I dismissed it right away. That's exactly what it's like, though.

I don't think I could even duplicate the problem if I tried, it seems so random, so even if it doesn't die with the fuel cap open, I'm not sure that it would point to a problem with the vent. I'll take a look at the vent tonight and see if I can see if there's something wrong with it.

Check your fuel line(s). I had the exact same symptoms 2 years ago and it turned out to be a fuel line that had a little kink in it that would sometimes restrict the fuel flow. Fixed the kink - problem gone. Ed

chrispysaki wrote:

Patton wrote:

Fuel starvation, perhaps from clogged vent in fuel cap.

Test run with fuel cap ajar (by-passes need for vent).

For whatever reason, not enough fuel is getting into the float bowls.

Good Fortune!

You know, each time it has happened I thought I had run out of gas. I checked and there was plenty in the tank, so I dismissed it right away. That's exactly what it's like, though.

I don't think I could even duplicate the problem if I tried, it seems so random, so even if it doesn't die with the fuel cap open, I'm not sure that it would point to a problem with the vent. I'll take a look at the vent tonight and see if I can see if there's something wrong with it.

If bike begins surging while riding, just unsnap the fuel tank cap and keep riding with the cap ajar (not snapped down) to see if the surging dissipates.
With a locking gas cap, test ride with spare key inserted in the cap to enable unsnapping the cap while riding.
If all else fails, at roadside, open the cap, allow sufficient time for fuel to fill the float bowls (use petcock PRI position if a vacuum petcock). Start the engine and resume riding with the fuel cap not snapped down.
If the problem doesn't re-cur with the fuel cap loose, that definitely points to a cap vent issue.

The so-called "vapor-lock" due to insufficient fuel tank venting may be more or less severe depending on fuel level.
Could be mistaken, but seem to remember that vapor lock is less with a full tank, and progressively worsens as the fuel level goes down.

Good Fortune!

Funny, I had this very problem too last year with my 650. I cannot pinpoint exactly which fixed it but I bought a new regulator and rectifier from oregonmotorcycleparts.com and never had a problem again. I also updated the old fuses to mini blade fuses.

chrispysaki wrote:

I've been having this very intermittent problem where the bike (80 kz750e) will suddenly begin to lose power until it dies completely. This usually takes about a minute from the time I begin to notice the problem. Once it dies, I pull over, wait a few seconds and the bike starts right up again and seems to run fine (although I take it a lot easier on the engine after this happens).

It's happened about four times in the last month, but the only commonality I can tell among each occurrence is that I'm going above 60 mph.

I initially thought the carbs were too lean and that it was overheating because it happened a couple times on very hot days. Yesterday, however, I rode about 40 miles during the day and it was about 80-85 degrees out. Then it died on the way home last night when the temperature was closer to 60 and I was going about 5-10 mph slower.

While riding it home, I thought I noticed in the rear view mirror that my tail light seemed to be flickering a bit, leading me to question whether it was an electrical issue. The head light seemed fine, however.

Does this sound like an electrical issue, carb issue, something else? I'd rather not spend a lot of time troubleshooting an electrical problem that doesn't exist.

Thanks,
Chris

I don't suspect either the carbs or any charging components.

The ignition system relies on a charged battery, and doesn't care how the battery stays charged. With a charged battery, the bike will perform just fine without any charging system whatever, until the battery runs down.

Consider some race bikes run a total loss system, meaning just a battery, and without any alternator parts, and no regulator or rectifier.

To check the charging system, measure voltage across the battery terminals at idle (look for 12~13 volts) and at 4000 rpm (look for 14~15 volts).

Good Fortune!

Thanks everyone! If it weren't for this place I'd be riding around town on my schwinn with a 500lb paper weight taking up space in my garage!