engine is rough on the take off

I have a 1981 KZ1100 and am having trouble gettng the bike get going from a stop at a light and so on.

It ran fine last summer and know that is has sat in my garage all winter it is running rough. Once you get the bike moving and get it above about 2500rpms it goes fine. It runs fine down the freeway as well. The only thing is getting off the line.

I had the valves adjusted, carbs tuned and replaced the plugs. It didnt work.

I am told that I may be able to adjust the needles in the carbs to open them up a little and this would help on the low end or check the grounds on the coils/ingintion system.

They also looked at the plugs and told me it looked like it was running lean. They also test for vacuum leaks around the carbs and told me there was no leaks.

I am looking for some ideas. I am going to clean the grounds and have the coils test. I can do this with little if any money. Please tell me you ideas and experiece. I dont want to spend a bunch of money on stuff that wont help or may be a waste.

Thanks is advance for you help and suggestions.

On the right side of the engine is a CD sized cover, inside you will find the mechanical ignition advancer. Give it a slight twist and see if it returns to the original position. if not,it needs to be removed, cleaned and lubricated. Some light oil like 3-in-one or sewing machine will work.Make note of how it's assembled as it can be installed 180 out.

Lube the pivot areas, and where the springs attach.

Another place to look is replacing the sparkplug caps as they contain a resistor to retard the RFI(the snap and pop when plugs fire heard on radio's)

Tried a fresh set of properly gapped sparkplugs? I'm thinking NGK B8ES or Denso W24ESU gapped to 0.032" might fix the problem.

Agreed...if running the stock air-box, filter type, carbs, displacement, exhaust...there should be no reason to change needle settings.

DoubleDub wrote:

Agreed...if running the stock air-box, filter type, carbs, displacement, exhaust...there should be no reason to change needle settings.

Definitely not a stock exhaust header shown in the OP's picture. Could be running lean because of that.

If it is stumbling coming off the line:

1) check fuel levels in the bowls with clear tube.

2) Maybe rich up the pilot jet setting (screws)?

3) Rich up the needle setting one slot, and it will make it come off the line better but may screw up other throttle opening operation (?)

The thing I don't understand is if it is jetted lean, how could it run OK last summer and get sick from sitting? It makes me wonder if the gas coagulated and gunked up something in the carbs and needs a better cleaning. You might try the seafoam in the gas for a while.

If it ran fine before but after sitting now stumbles?
Sounds like a Carb cleaning is in order with close attention to the Idle and transition circuits. Don't play with the jetting unless you know everything is correct; Ignition, Compression, no vacuum leaks, and the Carbs are real clean. Other wise you're masking over the real issue and will be to rich once you discover the actual problem.

Motor Head +1 Don't change anything, just clean the carbs.

This would indicate that an air passage got clogged over the winter. A rough acceleration indicates a "rich" condition. A "boggy" acceleration would indicate a "lean" condition.

Well thanks for all the advice. It was helpful but not the fix.

I cleaned out the carbs wich had lots of seddlement in them, cleaned the air box, cleaned the petcock and changed the gas in the tank. The bike still runs the same.

Starts right up, seems to run a little rough (no smooth).

With the choke on and the bike cold it seems to run a little better but stil rough.

Once I get over about 2500 to 3000 rpm the bike takes right off and seems to run good. It is just getting out of the hole.

Any other suggestions would be great. Thanks:woohoo:

davej6997 wrote:

...Starts right up, seems to run a little rough (no smooth). With the choke on and the bike cold it seems to run a little better but stil rough. Once I get over about 2500 to 3000 rpm the bike takes right off and seems to run good. It is just getting out of the hole. Any other suggestions would be great....

Reported issues are classic symptoms of partially clogged pilot circuits. And would here suspect that pilot circuits aren't yet clean (includes air and fuel passages, and jets).

Thorough cleaning of pilot circuits is sometimes an exasperating repetitive exercise.

Starting easily and running better when cold is likely because of choke assist to non-pristine pilot circuits.

Running better at higher rpm is likely due to transition away from pilot circuit.

Good Fortune!

Can you tell me more about he pilot circuit. I am not sure what that is.

It appears that it is the air filter, fuel lines and jets.

So since I have taken apart the carbs and sprayed them thoroughly with cleaner do you think I need to do more. If so, what?

I will replace the air filter as well.

Is there something that I can run through the carbs to help clean them?

I am fairly new to this but am willing to do the work. Just need some guidence. Thanks

The pilot circuits are very small passages in a carb that pass fuel from closed-idle to 1/8 open throttle openings. They can easily gum up over the winter, and all the spraying of carb cleaner will not help if the cleaner does not get into the circuits.

Someone mentioned Seafoam, and that may be all it needs. Buy a can at the auto store and follow the instruction. It may take one or two tanks of gas to clean it up, and if it does not work, then you should pull the carbs and soak them in carb cleaner, or boil them in water and lemon juice, etc, plenty of guidelines about this on the forum.

Having fun now.
Well I cleaned the carbs again and made sure to clean everythring this time. It still has the same problem.

I took it to a shop to see if I had missed something and they thouhgt it was the carbs as well. I had them clean them as well. Nothing changed.

I have adjusted the valves, cleaned out the gas in the tank, ran some Seafoam thru it, cleaned the petcock, synced the carbs, new plugs and have cleaned the carbs myself as well as paid a shop to do it as well. The bike still runs the same.

Here is what is happening again. I start the bike and it runs good with the choke on and cold. I ride it around for a few miles and it runs good. After running for a few miles I come to a stop and when I start again it spits and sputters to get going. I have to feather the clutch to get it going.

At this time it seems to be electronic. All I would know to do is start replacing parts one at a time and see if it fixs it. That can be expensive and may not work.

What do I do from here? Any suggestions on how to trouble shoot the electronics without having to replace them? Any suggestions on where to get new coils and so on? I figure if I am going to replace them I should replace them with good parts.

Thanks for all your help in advance.