Author Topic: Bike won't start. Whats going on with my spark plugs?  (Read 538 times)

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Offline gexdagecko

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Bike won't start. Whats going on with my spark plugs?
« on: December 27, 2015, 01:01:30 PM »
I have  76 Cb550K. Last time it ran was in September it only ran for about 20 minutes because I was riding it around the neighborhood. Now it will not start, I pulled the plugs and put in new ones. I posted a picture of the old ones and they are Cylinder 1,2,3,4 from L to R. All of them are black but 3 and 4 are VERY black. Are my piston rings gone?

Offline harisuluv

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #1 on: December 27, 2015, 01:59:59 PM »
If I recall I helped you on your carbs.  That means that the old plugs basically serve as no reference at all.  They could have already been fouled, then you put on your carbs, then pulled the plugs and you wouldn't have any way to diagnose the current state of the mixture.

If you want real data, you would have to now do a plug chop or ride it around for awhile to diagnose the current state. 

If you haven't rode it since september and you didn't have a battery tender then you might just have a dead battery.

Offline gexdagecko

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #2 on: December 27, 2015, 02:09:56 PM »
Of course I recall! I put in new plugs at the same time as I put on the newly rebuilt carbs! I rode the bike across town and got it from my sisters garage back to my parents(this was all in August). Then in September it won't start again so I change the plugs, and sure enough they are a little dark(I figured this was from my poor carb tuning skills) So I replace them and it runs fine. I leave the bike and go to school until December. It wont start again so I pull out the plugs with the advice to go up a heat range hotter. This is where I am at right now. The new plugs are in the bike, the battery is charged and the old plugs from September are the ones I posted the picture of.

Offline heyitsrama

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #3 on: December 27, 2015, 02:12:49 PM »
hows the compression on the motor? That seems to be covered in crud... I would check out this thread, and read around... http://forums.sohc4.net/index.php?topic=146912.0
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72' cb500
I can't believe it's not butter.

Offline mrfish2

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #4 on: December 27, 2015, 03:15:13 PM »
It wont start again so I pull out the plugs with the advice to go up a heat range hotter.

There's no reason to do this if everything is stock on your bike. NGK D7EA spark plugs are all you need.

Past that, we're gona need more info on your bike such as what exhaust you have, whether or not you have the stock airbox or pods, and your jetting in your carbs.

Also, unless those plugs are wet from oil (i can't tell from the picture) then it's not an engine problem.
1976 CB550K            1979 XS1100
1980 CB650C - Sold

It's a little motor and likes having the tits revved off it.

Offline gexdagecko

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #5 on: December 27, 2015, 04:41:22 PM »
Ok.

My bike had the airbox remobed and a 4 into 1 put on by the previous owner.
Harisluv rebuilt the carbs for me and jetted them accordingly.
This summer, after having the carbs rebuilt and the electronic ignition installed, it ran really well.

Offline harisuluv

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #6 on: December 27, 2015, 05:16:38 PM »
How long did you ride it over the summer when it was running well?

The settings are basically one notch richer on the needle jet, and 110 mains, stock slow.

You say the stock airbox was removed, does that mean just bare carbs and nothing else on intake side?

Offline gexdagecko

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Re: Bike won't start. Whats going on with my spark plugs?
« Reply #7 on: December 27, 2015, 05:38:48 PM »
Really just one ride because the turn signals stopped working. It ran better than it ever had on that ride though.

Ok good.

Yeah the stock airbox is unfortunately long gone, I want to put it back on but i don't have all the brackets.

There is a steel dragon velocity stack airbox instead. This one to be exact (http://s763.photobucket.com/user/dlhoulton/media/IMG_0138.jpg.html)
also installed by PO.