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Discussion Starter #1
Just got my carbs rebuild on a 1990 600R ninja I just bought. It has a 4 into 1 header (stock is 4 into 2) with a K & N air filter. Previous owner did NOT put a jet kit in. It does have adjustable needles though. I changed the needle settings twice. Now the E-clip is on the third from the bottom. I put one size bigger main jet in.

The problem, It is still running lead and also runs hot. Could the idle air screws out of adjustment be enough to cause this problem? My local dealer wants more money to fix the problem than I paid for the damn bike. HELP!
 

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How do you know it is running lean? Does it run better when it is cold or after it has warmed up?

Below 4,000 rpm the mixture is mostly controlled by the idle screws and the float level. Between 4,000 and 8,000 mostly needles and above 8,000 mostly mains.

A vacuum leak will cause it to run waay lean. You might want to look there before you start messin' with the jetting.
 

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Discussion Starter #3
When I take the spark plugs out they are white instead of the brownish tan color they should be. Ok, if the idle screws control at that range where should I set them? Stock is 2 turns out. The pilot jet is 35, should I go bigger or just turn the screws out? The stock main jet is 105 and I changed ot 110 because I had them from another bike.

I am also going to change to pod air filters tomorrow. I am sick of trying to jam the carbs in there with that stock air box. Any idea where I should go from there? Thanks. Sorry for all the questions but this is my first sportbike and they are different than what I am used to.
 

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I would not mess with the stock airbox or the pilot jet. You are opening a can of worms if you do. You can turn the idle screw out a maximum of 3 1/2 turns. Do you have the correct plug in the bike?
 

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Yeah, I have the right plug, at least according to my clymer manual. From the earlier question, (sorry forgot) it idles like crap until it warms up. I have been thinking that the lean condition is causing it to run hot. Mabe someting else is wrong. Just read that the engine running hot will make the plugs white.

The funny thing is that I can ride for a while before it gets hot. Example, today I rode for about 2o minutes, then I rode through a park about 25 mph, it started to warm up, when I left the park it was warmer and got hot when I stopped moving. And it never cooled back to where it was before the park.

I thought it might be a head gasket but there is no water in the oil and Saturday I rode about 70 miles without any other problems. It stayed cool as long as I kept moving.

What is the possibilty of the thermostat acting like this?

If I can't figure it out I am just going to sell the damn thing. I love to ride the thing, but I cannot affort to take it to a mechanic either.
 

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It is common for bikes to heat up when moving slowly. Do you have an electric cooling fan on the bike. If you do it should be coming on at about 200 degrees.

Here is a trick, If you go out and ride the bike when it is cold and basically put it through it paces before it is warm, if it runs better when it is cold the bike is running too rich. If you do the same thing after it is warm and it runs better the bike is too lean.
 

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Discussion Starter #7
It does have an electric fan and it does come on, at what temp I am not sure, the guage just has a green and red strip. I understand that it will run hotter when not moving. What concerns me is that it is almost on the red line at times. I just remembered, I had the idle screws just a little less than 2 turns open. I will try opening them more and see what that does.

The bike ran like crap when I got it from my friend. It would not start if it sat too long. One reason he sold it so cheep to me. I cleaned the carbs and now it runs great, except for the heating problem. I know it is just a matter of getting the carbs right. I am also going to call Vance & Hines tomorrow to see what they say about the pipe that is on there.

Thanks sw for the help.
 
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