running lean

1979 kz400 h1 ltd
stock

I gave up on podding my bike, so I put the airbox back on, but it is running lean, as indicated by the white spark plugs. As far as I know, everything is back the way it was when it was running fine, except I didn't switch out the 2nd main jets back. I put on bigger jets when I was trying the pods. But it seems to me that would make it too rich if anything. The bike otherwise runs fine, although it sputters a little on mid throttle. The float level might be slightly high, but it's not overflowing. Any advice? Thanks mucho!

Yeah you're right, the bigger jets should have richened things up if anything. I would check and make sure you don't have any air leaks around the carb boots that might be causing a lean condition.

Did you tinker or check the float levels?

Step one is to check intake manifolds for leaks. Step two is to set the float levels properly. What is your current jetting? main jet, secondary main jet and pilot jet?

wiredgeorge wrote:

Step one is to check intake manifolds for leaks. Step two is to set the float levels properly. What is your current jetting? main jet, secondary main jet and pilot jet?

How can I check the intake manifolds (preferably the poor man's way)? I tried spraying some WD40 around the intakes, as someone had suggested, but got no rpm response. I checked the float levels, and they are 1-2 mm too high. I don't know if that would cause a problem? My primary and pilot jet are the original jets and I think 70 and 35. My secondary jet I increased to 95 when I had the pods on, and never switched it back to the original. I cleaned the carbs fairly thoroughly just before I put the pods on. Also, both cylinders are showing lean condition by the spark plugs. Thanks for the help!

The WD40 trick is over rated. You have to wet the intake manifolds sometimes to find a difference in the idle. I also suggest you push on the carburetors... try rocking them a bit in their seats and see if the idle changes. Sometimes hard manifolds just don't allow a secure seat. The jetting sounds about right... I think an 88 2ndary is about what the stocker comes with and a 95 wouldn't make much difference till you were running wide open throttle. Did you run a wire through an of the jets by chance? Did you install a rebuild kit (possibly using the wrong air jets)?

I got two keyster kits, but the only thing I used was the 95 secondary main jet and I replaced the float needle, which appeared to be identical. I thoroughly cleaned all the jets. I'll try rocking/pushing the carbs and rechecking that all the boots are properly connected and sealed. Thanks again!

btw, would the float level being slightly high have an effect, and do I need to check it while it's actually running, or is it ok to check when it is not running. Also, my method of checking is by putting a clear tube on the drain nipple and holding it up to the side of the float bowl with the fuel switch on prime.

Post edited by: lmahaj, at: 2006/01/05 15:56

Check it not running and make SURE the bike is level. Do this by putting it on center stand and putting a 2x4 under the front tire. The fuel level high will ensure a rich mixture.

Proper plug colour can only be assertained after a full throttle run, hit kill switch, coast to stop and check plug.