Topic: Wet Spark Plug [ Now Carb Tuning/ Plug Chop Thread]

[campbmic]

I recently took my carbs off, reset all of the float heights, and bench synched them with the light method. I did this because I was having some smoking, popping, and a few flat spots on my throttle. After I reinstalled the carbs I took the bike for a test ride around the block. I could quickly tell it wasnt running very well. When I got back home #1 was cold. I pulled the float bowl and there was no gas in it, all the others had gas. I took off the float and reset the tang and it flowed. I'm not for sure if it was a stuck float pin or the float was to low.

Anyways, now all of my sparkplugs look pretty good except for #1 which is wet with gas. I'm not leaking any gas out of the overflow tube. So what would cause this condition? I know it means that the cylinder is running too rich but I tried messing with the air mixture screw and that doesnt help at all. Would the next thing be to adjust the slide height?

Thanks!

[nancy]

My guess would be if I had a wet plug, that I was not buring the fuel - i.e. the plug was naffed. Swap it out. Check for a spark on the cylinder by putting a good plug in that cap and leaving it out, suspended against the block/head and turn your engine.

[campbmic]

Oh ya sorry, the plug is good I've swapped it out

[Duke McDukiedook]

Check your float height with a clear plastic tube screwed in the drain screw hole, that will tell you your gas level, should be even across the carbs. That will tell you what is actually going on.




 

[campbmic]

If there ism't enough gas to start leaking out of my overflow tube then wouldnt that mean that there is no reason for a wet plug besides running to rich?

[scottly]

If the fuel level in the bowls is higher than it should be, the motor will run richer, even if it isn't so high that it runs out the over-flow. You started with a dry floatbowl, bent the tab on the float, and started fouling #1 plug. Check the fuel level, with a clear plastic tube replacing the over-flow tube, WITH the drain screw open!

[campbmic]

I pulled my bowl again to find that the idle jet (screw in one) had come out. I screwed it back in and viola! All of my sparkplugs are reading pretty uniform. All cylinders are equally hot when running the bike.

My bike is a 75 550K1 with MAC 4-1 and EMGO pods. I took the bike out for a test ride trying to synch my carbs up. I found the two following choke positions that my bike runs good in. Also, my needle is in stock position.

Choke 1/2 way open-
Spark plugs look pretty much perfect and bike pulls great up to about 6k. At 6k it starts to bog down and die.

Choke All the way open-
Spark plugs are white (lean) the bike pulls pretty good and will pull past 6k I havent tried to redline it because Im afraid the lean condition will really harm the bike.

So what does this mean?

[Duke McDukiedook]

Pods, you'll have to experiment with probably larger jet sizes and needle adjustments and plug chop each change.\

Fun, huh?

[campbmic]

Not fun

Im thinking my first step is to play with the needle position would I move it up one position to run richer?

[eurban]

Choose your main jet first then adjust needle position.   There is a good amount of overlap and the best results will be gotten from sorting out the main jet first and then adjusting the needle position accordingly.  Main jets should be tested at Wide Open Throttle and with a proper plug chop.  Search this forum and online for chop techniques and how to properly read the plugs. . . .Its not easy BTW . . . 

[flybox1]

here's a nice link for all on reading plugs....

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

[eurban]

here's a nice link for all on reading plugs....

http://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

Actually these types of charts are not really applicable to reading spark plugs for plug chop type carb tuning.  They require that the plugs have been used for miles of service and they only give you an overall sense of the mix.  They won't tell you for instance that your main jet is too large but your main jet needle position is set too lean.  They also don't compare so well to plugs colored by engines running on fuels with ethanol added.  Performing a plug chop for main jet sizing requires starting with a warmed up engine, installing new plug(s), bringing the bike quickly up to the top gear ranges and holding the throttle wide open for a good 10-20 seconds, followed by pulling in the clutch, hitting the kill switch and coming to a stop.  The plug then needs to be examined for the carbon ring deep inside the well where the porcelain meets the metal of the plug.  Flashlight and magnifying glass will likely be required or you can cut the plug with a grinder to see what you get.  Here's a few links for consideration . . . . www.dragstuff.com/techarticles/reading-spark-plugs.html ,

, http://www.strappe.com/plugs.html ,  and a final one with some different approaches http://www.4secondsflat.com/Spark_plug_reading.html

The strappe.com one is particularly good.  Read towards the end for reading for main jet / mixture.  Like I said before, it's not a particularly easy process.  

[campbmic]

Whats a good source for cheap main jets?