Author Topic: Spark Plug colours  (Read 714 times)

Offline Terryb

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Spark Plug colours
« on: 14.09. 2014 20:02 »
All,

Can anyone tell me how to rectify the fuel mixture between cylinders. The spark plugs on my Shooter have started to show dissimilar colours. Near side the colour is normal and the off side is showing heavy deposits of soot. Can the tappet clearances cause this?

Online muskrat

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Re: Spark Plug colours
« Reply #1 on: 16.09. 2014 08:56 »
G'day Terry.
Different tappet clearances would barley be seen as different plug colours. More likely to be rings or intake valve guide. A7's don't suffer from induction bias as much as A10's, so if it isn't burning a bit of oil, that is the next culprit.
Another good test for a pair of colourtunes  http://www.halfords.com/motoring/garage-equipment/car-tools/gunson-colourtune-12mm-sparkplug-tuner
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online bsa-bill

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Re: Spark Plug colours
« Reply #2 on: 16.09. 2014 10:11 »
Colour tune's a good tool as well as mixture it show up  no spark
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline Terryb

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Re: Spark Plug colours
« Reply #3 on: 18.09. 2014 09:46 »
Hi Guy's,

Thanks for the tip, I'll pop into Halfords and try the colour tester.

Went for a 140 mile ride yesterday, still showing soot on the right hand plug. Not burning oil and no black smoke from the exhaust showing. Performance seems to be unaffected.

Offline BSA_54A10

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Re: Spark Plug colours
« Reply #4 on: 18.09. 2014 09:58 »
If the plug is not firing all the time that can cause builds up of soot as well.
Howeer that usually gose hand in hand with a few pops in the exhaust
Bike Beesa
Trevor

Offline a101960

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Re: Spark Plug colours
« Reply #5 on: 18.09. 2014 10:41 »
Quote
still showing soot on the right hand plug. Not burning oil and no black smoke from the exhaust showing. Performance seems to be unaffected.
I had a similar problem.  Tried all sorts of things including fitting anti bias gasket to eliminate it. What finally cured the problem in my case was removing the carb, thoroughly cleaning all the jets and passages with brake cleaner, followed by giving it a good clean in my ultra sonic tank. There was lots of crud in the idle circuit. Why was only one cylinder affected? I really don't know. You would be amazed at how much muck appeared in the ultra sonic tank fluid.
John