how lean is too lean

[smagnusen]

I pulled my plugs the other day and was not happy. 1, 2, and 4 were snow white. 3 is black but that's a diffferent problem. I've done the whole valve shim, timing, o-ring, carb dip, highest rpm, syncing, airbox thing. My jets and settings are stock except for raising the needles with a couple radio shack washers, though that should richen it up. There is also a K&N air filter.

The bike starts easily and once it's warmed guns throughout the throttle. I am concerned though because my oil, which is only a month or so old, is very dark. The bike will blow a little white smoke from the right stock pipe if I'm stuck in traffic. I do have an in-line fuel filter because there is a little rust in the tank and I'd rather it not be in the carbs. If I can run solidly between 5-7K doesn't that mean it's getting enough gas? Could the filter be causing it to run lean?

Could an improperly oiled air filter cause this? I had gas get in a while back and wondering if that could have wiped out the oil coating.

Another thing, I did this chop after the bike had idled for awhile. I suspect that some will say that these bikes idle lean and that could have scrubbed the porcelein, but wouldn't that only be in the top 1/3'd of the plug? I refer to this article. (Good read by the way) The plug should still retain information on the lower portion from mid-wot. Plus my oil is burning... Thanks in advance!

 

[walt]

Lean fuel mixes will raise the operating temp of the motor and break down the oil very fast. Oil starts to break down around 220~230F. Oil also carries away motor heat as well lubricating the moving parts.

 

[omaharj]

Nothing to offer-great link tho! I wanted to post so I would be informed of any updates. I think I can learn something here.:shock: thanks,RJ

 

[Guest]

This is a too lean condition. :shock:

 

[Ironriot]

This is a too lean condition. :shock:

Holy crap!

 

[tfb]

If you got petrol on your K&N filter, re-oil it. These filters allow waaaay better breathing than stock, and so things run a bit leaner with them fitted to begin with. If you have somehow wiped the oil out of it, expect it to run even leaner.

One thing you have not mentioned are leaking rubber inlet manifolds. As they age, these harden and crack, allowing air to leak in & for things to run very lean indeed. So if you have not checked them, that could be another place to start. If any show signs of hardening or cracking, get a new set.

 

[smagnusen]

Yes chef, that scares me to death. Exactly the fate I'm trying to avoid.

ftb, I did replace inspect the intake boots and replace the o-rings.

Will oil the filter and take some shots of the plugs when I can.

 

[KEITH KRAUSE]

The smoke out of the right pipe and #3 showing a black plug suggests an oil leak (burning oil...valve stem seal/guide, piston rings...). Without all 4 plugs burning correctly, the bike will never run well. You need to repair the oil leak first.
With a basically stock bike, there's no need to raise the jet needles.
Yes, the K&N filter needs to be correctly cleaned and re-oiled. A lean mixture will result if the K&N filter is under-oiled. Clean and rinse from the inside out only and under low water pressure. Shake and allow to air dry.
You can't get accurate plug reads after idling. Test the pilot circuit at approx' 35/40 mph steady cruise in 4th gear, level or uphill is best. You want to test at the minimal throttle position.
Test at solid 1/3 throttle to check the jet needle mixing. Full throttle for the main jet.