Fouling out left spark plug

ymisobd · Posted: May 7, 2009, 11:16 pm Post subject: Fouling out left spark plug

Let me start off by saying hi to everybody here. I am a newbie to the XS world, having bought this 1 3 months ago. But I'm having a blast with it! Well, I will once I figure out what wrong.
Ok, the problem; the bike keeps fouling out the left side spark plug. The bike is a 81, so it has the stock electronic ignition. The carbs are stock 34mm Mikunis, but aftermarket airpods. The exhaust is a aftermarket (not sure of the brand) 2 into 1 with a megaphone and removeable baffle system with no packing. I have wrapped the head pipes. The bike has good compression, I tore down the carbs and inspected and cleaned them, and checked for good spark. I am a ASE mechanic, so I no my way around a wrench Very Happy

, but this problem has me baffled.
I can throw a new set of plugs into it, and it runs AWESOME! But once I put some miles on it (varies based on ambient temp and such) it will foul out that 1 plug.
Any ideas would be greatly appreciated. Thanks in advance!

jayel · Posted: May 7, 2009, 11:27 pm Post subject: Re: Fouling out left spark plug

that dual coil iggy fires one plug normal and one ground to electrode (bass-ackwards) this is not to say your choice of air filters and pipes don't come into play, plenty of the stockers run just fine so you might try running a short while without those filters and see what happens

xsjohn · Posted: May 7, 2009, 11:28 pm Post subject: Re: Fouling out left spark plug

Mix screw turned out a bit too far maybe....float too high on left....some small conical pods will make them run rich..........

xsjohn

BigGeorge · Full Member Joined: Apr 13, 2008 Posts: 267

Sounds like you may be losing that good spark under load... Being a mechanic I assume you checked simple things like the plug wires?........ BG

ymisobd · Posted: May 7, 2009, 11:50 pm Post subject: Re: Fouling out left spark plug

Yeah, checked resistance on the wires, and continuity on the coil. Both were with in tolerances. And I read the article on MikesXS on the mixture adjustment on the carbs. The plugs on the adjusters were already pulled, so I set them at both 2.5 turns out (though it was already fouling that 1 plug). I have ordered a sync tool from Mikes so that I can set the carbs proper.

xsleo · Posted: May 8, 2009, 3:54 am Post subject: Re: Fouling out left spark plug

Instead of buying a sync tool build one, I did.
Go to Lowes, they sell a clear plastic hose 1/4 inch out side diameter, 20 foot long. A roll cost a few bucks.
At home unroll the hose, find the center. Put this spot at the bottom of a board. An inch board about 3 or 4 inches wide, 2 or 3 feet long. Run the hose up the center of the board. I held it in place with clear packing tape.
I put enough tranny fluid, nice red, easy to see, in the hose to fill the loop on the board about a foot or so up both sides.
Hang on the wall, hook one end of the hose to each hose barb on the carb holders.
This is a very sensitive gauge, a very small turn of the balance screw causes a drastic change in the fluid level in the hose. Just adjust till the level is even.
On mine the fluid bobbles up and down in the hose about 3/4 inch.

Joseph · Full Member Joined: May 22, 2007 Posts: 767 Location: NY

Do you hook it up and then start the bike or hook it up w the bike running. Is there a chance the carb will suck the fluid into the mottor? I am asking because I want to do this. I was considering using maybe mystery oil in case it sucks into the motor.

xsjohn · Posted: May 8, 2009, 6:38 am Post subject: Re: Fouling out left spark plug

""""""""""""""""""I set them at both 2.5 turns out """"""""""""""""""

Try setting the left at 2 1/4 turns out or so.......and leave the right alone for now.....

xsjohn

xsleo · Posted: May 8, 2009, 6:52 am Post subject: Re: Fouling out left spark plug

Hook the hose on then start the engine. If you try hooking the hoses on with it running, when you unplug one hose barb the engine may stall. If it don't when you hook one end of hose to the barb it will suck the fluid in to the engine. Thats why I chose tranny fluid, it wont hurt any thing.

ymisobd · Posted: May 8, 2009, 8:34 am Post subject: Re: Fouling out left spark plug

Wow, thats a pretty cool (and cheap) sync tool. Guess I'm stopping by Home Depot on the way home tonight...:)

jayel · Posted: May 8, 2009, 9:02 am Post subject: Re: Fouling out left spark plug

if you put a aquarium air valve into the line you can regulate how hard the intake pulses are pulling the fluid in the hose, slows it down enough that you don't pull the fluid into the engine

jayel · Posted: May 9, 2009, 7:20 am Post subject: Re: Fouling out left spark plug

here's a carb balancer build guide

650wiki.org/index.php/...m_edition)

Retiredgentleman · Posted: May 9, 2009, 11:47 am Post subject: Re: Fouling out left spark plug

22 feet of 3/16" ID, 5/16" OD plastic tubing; a wooden board, some red liquid................that's it!

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