The big bog

Before I go ripping the carbs off the scooter I figured I'd run my question up the flagpole.

I have an 80 LTD 1000. The bike has always been a bit cold-natured. It sputters a bit between 1-2k until its fully warmed up but other than that it runs pretty good so I haven't addressed the cold sputtering. I'd rather ride it! It fires right up etc. Until recently.

The last time I rode it I felt the urge to get down a bit, so I did and it boogied as it typically does. Love this bike! Afterwards the engine began to bog down when the throttle opened more than 3/4 of the way. I laid off hitting full throttle and everything was fine. On my way home the bike would bog down after passing the 1/4 throttle mark. DRAG!

The bike still starts right up and runs fine unless you pass that limit of a quarter throttle, then it bogs down. It's like its running out of gas but If I new that for sure I guess I wouldn't be asking the gods for guidance right!? Any input will be greatly appreciated and as un-PC as it is, Merry Christmas yall!

Won't comment on the carbs, but check the simple stuff first. Do you have an inline filter? Could be dirty, likewise you could have crud in your tank thats clogging your tank outlet, under accel.
F' PC, MERRY CHRISTMAS to you also;)

Several things to check:

1. Clean air filter(s.
2. Correct heat range and gapped sparkplugs.
3. Sparkplug wires in good shape
4. Sparkplug caps in good shape (tight, good continuity)
5. Ignition producing a hot fat spark

If all the above looks o.k. then your bike might be a candidate for the "Wired George" relay modification. Many older Kawasaki's benefit from this work.

His website www.wgcarbs.com list parts and diagrams. Many guys here have done this easy to do modification with restored engine responce like new!

sounds like it might be a plugged fuel filter give that a look before you start tearing things apart.

Everything suggested so far is good stuff but from the description (being cold blooded, sputtering a little and now not liking a handful of throttle) says to me it's time to clean the carbs. Then get yourself some new fuel filters. The coil mod is a gimmee. Nice cheap easy mod that needs doing anyway. But I think ya needs to clean those jets, circuits, seats and bowls! There are a couple of good write-ups around here on how to do it or Wired George can make them new again. Most of us like riding better than wrenching (notice I said most) but there comes time these old girls want more than a good romp. :blink: :ohmy:

All great responses and some pretty fly bikes too! Appreciate ya.

I'm going to start checking the tank to carbs cleanliness factor and go from there. I'll dump the results back up here as I go. Appreciate the tip on the ign relay tip. That will be next.

Merry Christmas and be careful out there on your scooters! Lotsa lost folks rollin in their cages today.

I had a similar issue once...ended up the battery was disconnected (I was young and stupid and didn't tighten one of the terminals enough). Very little power under 50-100% throttle, but it cruised along the Interstate at 65 just fine.

The bike drove all the way from Madison to Chicago and then it wouldn't start...go figure.

Would concur with above posts by first suspecting a fuel starvation problem, meaning insufficient fuel supply reaching carb fuel intake(s).

While the bog may well indeed be due to dirty carb internals, or other reasons already noted, would suggest using a strobe type timing light to inspect for correct operation of the ignition advancer unit before addressing the carbs. Possibly, the advancer unit is sticking in its idle rpm position and failing to advance as its supposed to do with increasing rpm.

As known, carb tuning should generally be addressed last after other tuning components (i.e., compression, valve clearances, all aspects of ignition, adequate fuel supply, and ample clean air supply) have been checked and assured being up to specs.

Proper carb function is predicated on the other components, and even perfectly clean carbs can't really be tuned/adjusted to compensate for non-carb related faults.

The peanut gallery has spake.

Good Luck! And MERRY CHRISTMAS!

If you have CV carbs, check the diaphrams too. My 400 bogged big time when I tried rolling the throttle past half way. It's a long shot, but give you're symptoms, if you have the CV's, you could be looking at a torn hole in the diaphram that just got larger when you pushed it.

Am thinking here equipped with manual petcock and dual fuel lines into carbs with a fuel pump.

Would drain tank and remove petcock. Disassemble and clean petcock, especially the tubes and screens that go up inside tank.

Remove tank. Drain and flush, fast dump through filler hole while holding tank upside down. Add some fresh fuel, swish it around, and dump again. All toward objective of removing all grit and crud from inside the tank. Because this grit and crud is likely suspended in the fuel hovering around and collecting on the petcock intake tubes preventing sufficient fuel flow into the petcock.

Also assure the round screen inside petcock is clear of debris.

Good Luck!

fredgarvin42 wrote:

All great responses and some pretty fly bikes too! Appreciate ya.

I'm going to start checking the tank to carbs cleanliness factor and go from there. I'll dump the results back up here as I go. Appreciate the tip on the ign relay tip. That will be next.

Merry Christmas and be careful out there on your scooters! Lotsa lost folks rollin in their cages today.

Only thing not mentioned to check is the float levels. Bogging on throttle hit can be caused by fuel level riding too low in the bowl. I think fuel/air filter or dirty carbs is more likely too.

Link14 wrote:

If you have CV carbs, check the diaphrams too. My 400 bogged big time when I tried rolling the throttle past half way. It's a long shot

Not as long as you think, I just fixed the same problem on my KZ750. The rubbers get a "curtain" effect near the tops and the little cracks hide in the seams. I didn't see them until I held them up to a light and stretched the rubber smooth.... had two holes in one and three holes in the other. Got new slides and it runs fantastic now.