1100EZ with intermittent surging

[Anonymous]

Riding home last week the bike was surging like it needed to switch to reserve. Did that, then to prime but to no avail. Pushed to a gas station, topped up and after lots of waiting and cranking, it started AFTER full choke on a hot motor. It ran well the final 20 freeway miles home. Thought it might be a petcock problem but no re-occurance all week. Then again two days ago with 2.5 gal. still in the tank it began surging again (at 70 mph) and this time it appeared to catch on reserve and ran clean til I got gas and topped off. Today on a freeway ride to work with nearly a full tank it started surging again and no petcock position was altering the performance. I rode the next 20 mi. in 3rd and 4th at diminished power, with occasional bursts of correctness at full power, then parked it at a friends and borrowed his car. I don't think it's a carb or fuel problem because of the randomness of the problem over 2 weeks of riding (5-80 mile rides) and the different fuel levels in the tank. I've been running the electrex stator and r/r conversion for about 5 yrs now, but after parking it then trying the starter it turned over very slow before catching. Tomorrow I'll start to work on it but do you think it could be the coils? It's been a real "ghost in the machine" trick with its on again/off again problem. I love this bike and will never get rid of it. Rode it to Cabo and back 12 years ago and until this episode it's never let me down. Totally reliable. I've had it apart in the dining room (no wife) over the winter, split the cases, undercut the gears, re-rung it..you name it. But I'm totally freaked out about the electrics and my knowledge of multi-testers. Any ideas or thoughts would be appreciated.

[tfb]

Do you have a fuel filter installed? Could be the dreaded 'vapour lock'. Might also be a blocked fuel cap breather.

To confirm that it's a fuel problem, try this: when it starts surging, pull your choke on. If the surging stops, then it's fuel starvation for some reason.

In warm weather, having a fuel filter (with a large-ish bubble of air in it) can contribute to this.

Just be REALLY SURE it's not a fuel problem, before you go stuffing around with coils, etc. Because most often, these things are fuel-related.

Also, have you tried seeing if there's any water in your fuel tank or carbie bowls?

Happy hunting,
Mike.

[Jethro]

This happened to me just recently. Rode all weekend no problem, then on the way home I was going good on the highway (maybe 5-6k rpms) and I felt like it was running out of gas. Got to a gas station, filled up, let it cool down and it ran fine, for a few days. I spent hours checking things out- swore it wasn't the petcock- but it was.

The moral of the story, if it feels like fuel starvation, it probably is, even if it seems unlikely. When you have fuel starvation problems, start at the top and work down in this order:
1. Check if fuel is in tank
2. Check gas cap vent
3. Check petcock (mine had crap in the main port- no position changed things and it came and went)
4. Check fuel line condition, size, fitment
5. Throw away any add on fuel filter (they are garbage)
6. Check carb fuel path
7. Check float needles
8. Check float needle filter screens
9. Check and clean jets and carb ports

[Anonymous]

1100 EZ intermittent surging

Thanks for the replies. I will go back and start with the fuel system. I can't get to the bike until tomorrow but I will keep you posted as to the progress and results. The bike does have an in-line fuel filter. A little gold sucker that's been there since my Mexico trip 10+ years ago. That will definitely go. And I'm sure the fuel line from there to the carbs is the original (23 yrs old) so that too will be replaced. I'll also check for kinks or clogs in the breather hose and thoroughly inspect the petcock. I did replace the original there awhile ago. I'll try all that first before I yank off the carbs. My experience there has always been an ugly knuckle busting wrestling match. And the choke application when fuel starved is an easy and invaluable tip. Thanks again. Still, I've never heard of "vapor lock" happening on a bike, or this bike. Is that really possible? And if there is water in the fuel, isn't draining everything correct vs simply pouring in a fuel additive or "dry gas"?

[tfb]

5. Throw away any add on fuel filter (they are garbage)

Well said. They are next to useless. If they filtered out rust sediment, that would be great, as most untreated GS tanks produce it over time. But no, the rust sediment always goes straight through to your bowls every time, filter installed or not. So indeed, garbage and a waste of money. And, a major cause of vapour lock.

OK, I feel better now for getting that off my chest!

Still, I've never heard of "vapor lock" happening on a bike, or this bike. Is that really possible?

It sure is. I used to have a black GPz900 that was doing the whole surging thing, then cutting out -- especially on summer trips longer than say 50kms. You'd roll to a stop, wait two minutes, then start the machine like nothing had happened, go another 50kms, and repeat. So off I went barking up every electrical tree, to no avail.

In my sheer exasperation I rang up a Kawasaki dealership. "Is yours the black model (1989)?" he asked. "Yes," I said. "And do you have a fuel filter installed?" "Yes..." "Throw away the fuel filter," he said, "it's vapour lock." So I asked him what the bike's colour had to do with it. He said that the black colouring meant my model of GPz got warmer under the tank than on other machines, which meant the vapour lock was more likely to happen. I wasn't convinced, but I had nothing else to try. So I ripped out the fuel filter. And the problem was gone.

Anyway, after I bought my Katana, I was riding it home (200km trip) and it did the same thing, but at about 70km intervals. So when I got home, I ripped off the fuel filter, and the problem hasn't returned.

So yes, it's a real problem. If you trawl around a bit you'll find other posts on this forum giving similar stories.

Hope you get it sorted soon,
Mike.

[Jethro]

My 81 had a Kreemed tank, and I was told (by an idiot) that I MUST keep an in-line filter installed at all times. I believed him so much that I spent oodles of money trying to fix what I swore was a carb, then electrical problem. On one of the many days I was pulling the bike apart and the carbs out, I broke the fuel filter. I had more fuel line, so I figured I'd just run a few days without the filter until I could pick one up. Bike ran perfect, and for the first time I felt what it could really do. I have a personal vendetta against in-line fuel filters- can ya tell?

[crag antler]

My 81 had a Kreemed tank, and I was told (by an idiot) that I MUST keep an in-line filter installed at all times. I believed him so much that I spent oodles of money trying to fix what I swore was a carb, then electrical problem. On one of the many days I was pulling the bike apart and the carbs out, I broke the fuel filter. I had more fuel line, so I figured I'd just run a few days without the filter until I could pick one up. Bike ran perfect, and for the first time I felt what it could really do. I have a personal vendetta against in-line fuel filters- can ya tell?

That does it. I am geting some fuel line and pulling my fuel filter off. Last mechanic put it on and now it is of of there.

[Anonymous]

1100EZ with intermittent surging

Okay, so I was replacing the fuel line today to rid the bike of that in-line fuel filter when I found the real culprit. The nylon connecting block between the Electrex stator (3 yellow wires-1 red wire)and the R/R looked real ugly. On the R/R side, one of the yellow wires was completely fried through and another was well cooked and fusing to the third. It looks like I've got some multi-tester work ahead of me. Somewhere in this baby there's either a short or bad R/R or, God forbid, a fried stator. I was able to re-connect all 4 wires with clean spade connectors and it fired right up and ran clean and fast the 40 miles to home. Once here though, now depressing the starter button yields nothing but a dimmed check-light panel. Clue?
Last fall I noticed the red power wire heading from the R/R to the stator had some definite hot spots, to the point of melting the insulation and attempting to short out on the frame. At the time I just replaced the wire and didn't determine if there was a deeper problem. I just thought the wire had rubbed off some insulation and was overheating because of a short. Now I'm going to track all these wires down, check all over the damn place for shorts, re-read my Stator Papers and do all the checks concerning the R/R and stator output. All of the fuel and fuel filter and petcock info was helpful, VERY HELPFUL. And I'm glad to be up and riding again. Now to re-learn my multitester basics and track down what's causing all this. Thanks again for your posts and help. I'll keep you posted as to what the current problem and cure are.