Keeps running worse!

[Mac]

My "96 ZXI 1100 started fine and ran fine except it would not go over 35 mph(It was supposed to be a rebuilt motor. I bought the ski in pieces and put it back together.) I rebuilt the carbs and set the pop off @ 28. It ran the same except it would only go about 30 mph and started running ruff after about 10 mins. I lowered the pop off to about 18 and put new plugs in.I took it out and it will only do 10 mph and is missing big time.The #1 plug had clean porcelan on the plug but the electrode was black and slightly wet. The # 2 and #3 were all black and slightly wet. I did a compression check and #1 118, #2 125, #3 125. What could I have screwed up rebuilding the carbs or what should I check next? Is this too much of a difference in compression? My season is almost over and I would at least like to find out what is wrong before I winterize. Any help is greatly appreciated. Thanks.

[wmsky]

Re: Keeps running worse!

all black and slightly wet

It sounds like your engine might be flooding. First check that the choke plate is fully open when you turn the choke off. Second, your popoff might be so low that it is staying open all of the time and your engine is getting too much gas. I would set the popoff to original spec and retune the carbs from the beginning. Only play with the popoff after you get it running right first.

Bill

[Mac]

Re: Keeps running worse!

Choke is all the way open and mixture screws are set at factory specs. I cant find a spec for pop off but was told this is where it should be. I looked down the throat of the carbs as it was running and didnt see any fuel dripping. I believe this is what happens if pop off is set too low. The only mod I have is after market flame arresters.

[wmsky]

Re: Keeps running worse!

You said you got the ski in pieces. Is it possible that the previous owner replaced the jets in the carb with larger jets?

Check that you are getting adequate spark.

How old is the gas? Are you using premix? I'm not sure if too high a ratio of oil to gas could cause the problems you are having. Are you getting any oil blowing out the exhaust?

Does it die or seriously bog down if you open the throttle suddenly from idle? I would think it would if you are running way too rich.

Bill

[Bill O'Neal2]

Re: Keeps running worse!

I don't know the exact number for the pop off, but I think it is closer to 40 psi.

[Mac]

Re: Keeps running worse!

Thanks for the reply! The jets could be larger. How do you tell what size they are? Gas is fresh and I pre mix 50/1. I dont see any oil blowing out the exhaust but it is a little smoky. Yes it had a huge hesitation and sometmes it would die when accelerating from idle. I do have even blue spark @ all three plugs. I did have to trim an 1" off the coil end of # 2, it was pulled out durring installation. As far as pop off I cant find a spec anywhere. I started @ 30 because thats was the average of what the carbs were set at when I took them a part. I then lowered it to 20 as was suggested. Maybe I should try turning in the mixture screws ? Anything else I should do or check?

[Mac]

Re: Keeps running worse!

I turned in the high and low mixture screws 1/2 turn. It ran a little better but not much. If I give it a little choke it will go almost 20mph but still missing really bad. I noticed today when i took it out that the rubber exhaust hoses were about to blow. They were really soft and seperating. I just replaced them about 6 - 8 hours ago becuase they were bad. What would cause them to go bad again so soon? One last thing, I took out the oil tank because I premix, do I need to do anything with the wiring? Thanks again for ANY help.

[Mac]

Re: Keeps running worse!

Anyone have any ideas? I'm at a loss and would like to figure it out before I winterize it. Thanks.

[wmsky]

Re: Keeps running worse!

I think that since it started running worse when you decreased the pop off, and Bill O'Neal thinks the pop off is probably supposed to be closer to 40 psi, you should try increasing the pop off pressure. You might want to call a dealer or mechanic and see if they can tell you what the factory spec for the pop off pressure is. Otherwise increase it and see if the engine runs better, checking the plugs frequently to make sure you don't go too lean. There's a how-to on this board at http://server1.sbtontheweb.com/forum...ad.php?t=13965 on how to adjust the pop off pressure. Two things jumped out at me when I read the article:

1) If the pop-off point is set too low, there isn't enough resistance on the needle to stop the fuel pump flow, and the jets are over-pressurized, giving you a rich condition you will never tune out.

This pretty much describes your condition.

2) NOTE: You cannot accurately test with the pump body and fuel filter still attatched to the carb - you MUST disassemble it and test directly into the fuel inlet orifice, where the fuel filter sets. Otherwise you are testing through the pump checkvalves, throwing your readings off, too high. If you have an external fuel pump, this does not apply.

If you are not testing the way they say, your readings may be high and your pop off pressure may actually be lower than the readings you are getting.

[addicted2speed]

Re: Keeps running worse!

You said it was pieced back together, right? do you have a check valve in the return fuel line and is is going in the right direction? (not even sure that they are directional, but I think so) I'm thinking that too much of a restriction in the return line could cause a flooding problem also.

[SuzanGPR]

Re: Keeps running worse!

Check with James Crone at Performance Engineering. He's the region 5 kawi specialist and I'm sure he can help you out. Good luck with it! :) He goes by the nickname of ZXIman on http://pwccentral.com

[Mac]

Re: Keeps running worse!

Thanks for the reply. I'm pretty sure the lines are on right but where would a check valve be? Would it be inside a line or is it a seperate unit? I'll see what I can find in the Kawy manual but the translation is not that good.

[addicted2speed]

Re: Keeps running worse!

It is inside of the return hose to the tank and you will only see the center spacer of the valve between the two ends of the hose that it connects (like a butt connector for a hose made out of brass) (but no hose clamps on it though).... Without it you will not run right... take it from experience.... Rob

[Mac]

Re: Keeps running worse!

Thanks, I'll check and see if its still there.