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Black plugs

  • Thread starter Thread starter Crage
  • Start date Start date
C

Crage

Guest
I purchased my bike last summer and did a lot of work on it. Cleaned the carbs (over night soaks), and replaced o-rings as detailed on site. Also got new rubber carb boots for both sides and also a new air box and filter. Replaced the plugs as well. Bike ran great all summer after this.

I fired it up for the first time this year and #4 is cold. I pulled the carbs just enough to pull the bowl off #4 and clean the pilot and main jet. Still cold #4. I am getting a spark by the way. I then started pulling my plugs. I noticed that they are all black and wet. #2 has some brown on the little finger (for lack of better words). I obviously have issues all around.

Also I pulled the plugs a few times after all the work and they looked great. I'm in the process of cleaning my tank now, the only other thing I can figure is the rust has gummed up my carbs over winter?

I think I'm rich, but where do I start? I have the carbs pulled now but would rather not do another complete dissassembly if I dont have to.
 
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I know how you all love pics. From left to right 4 3 2 1. 4 is the worst followed by 3, then 1, then 2. 2 does not seem that bad to me but I'm no pro.



 
I just install a brand new battery last weekend. The starter turns better than ever now.
 
Ok, tested voltage going to the coils:

1 and 4 coil has O/W and W going to it.

2 and 3 coil has O/W and Black/Yellow going to it.

According to my wiring diagram oranges are my hots. So when I test voltage at the wiring harnesses to the coils (between o/w and w, o/w and b/y) I get ranging millivolts. If I test o/w at both harnesses to negative on the battery, I get a solid 12.3 volts. W and B/Y both come from the ignitor. Bad ignitor? After reading up on ignitor testing, I dont think thats what it is.

I have spark at all my plugs but it seems weak to me, but I'm not sure what its supposed to look like. I did notice that my caps (while laying unhooked) sometimes spark to the engine. The caps insulators have some cracks. Think this is my only problem?
 
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Seems like you got good juice to coils; Might as well check plug cap to plug cap resistance ( 1 to 4 and 2 to 3)- should be around 24 to 32 kohms, but sometimes hard to tell. Best to cut off 1/4 inch of each plug wire to expose fresh copper for cap to bite into. On each coil, plug wire to plug wire (caps removed) resistance would be about 12 kohms, if you have stock coils!


You sure your "choke" isn't slightly stuck open?
 
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Caps removed

on the 1 and 4 coil I'm getting 12k ohms wire to wire
on the 2 and 3 coil I'm getting 12k ohms

I'm not positive that my choke isnt slightly stuck open but why wouldnt my 4 cylinder fire at all? To my knowledge I had gas and spark.
 
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Im really thinking my spark is weak but I need to see what it is supposed to look like. Anyone?
 
After testing in the dark, they are all getting a good blue spark except the #4. It is weak and white. I know the caps are bad because their connectors are split and they have shocked me. They arent showing any archs in the dark while connected to the plugs though. This has been on my to-do list for awhile, ordering them now.

Ive tested the coils as stated above.
 
Ok, little update here.

I installed new plug caps, and plugs. Also did a quick clean of the carb jets while I had the carbs pulled. No more black plugs, and #4 is firing!

On the contrary, after a 10 minute ride I have white plugs.... She is also quite slow to respond in the mid range (3k-4.5k rpms). This tells me she is running lean. Ideas?

I have stock air box and brand new carb boots all around. (carbs were fully taken down and cleaned last spring and yes I changed the o rings)

I do know that I have not oiled my filter. Is this necessary on a stock set up?
 
yes and yes.

I opened my air box last night and noticed that the filter wasnt seated correctly and air was bypassing the filter. I fixed it and took her for a quick ride. This seemed to have helped my midrange issue quite a bit. I pulled a plug after the ride and it was still pretty white. Mind you this was a short ride, it was getting cold out. Should I take it for a longer ride before I mess with it any further?
 
Well you seem to know what you're doing, but I have to ask since I didn't see it, are they the right jet sizes? When I got my bike I was horrified to see someone had put in main jets that were many sizes too big.
 
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