could it be the air fuel mix is different for each chamber. in this scenario maybe the middle two ports recieve a majority of the flow, but not sure whether it affects AF ratios in any way. fuel (petrol) is more heavy, and due to inertia is perhaps less likely to change direction in an intake manifold, heading straight into the middle two ports?

Yes, the deposits are a bit heavy, I think that is due to the fuel addities which come in the gasoline here.

The color is exactly the same on the middle plugs and outer plugs, only that there is not color all the way around on two of them.

These are vintage Champions from the 1980s, good stuff. They have been in the A12 for about five years.

sorry to rape your thread dd but i have a question about my plugs

there perfect colour but they seem to make the motor hard to start and when i do get it running it wont idle right ,idles too low or just dies ,what does this sound like ,ive eliminated ignition ,as ive put a different coil and points in it and it does the same thing

carbs are perfect ,all the jets are clean ,no vacume leaks ,fuel pressure is perfect and there balanced well

could it be my plugs making it stall ? its doing it across all cylinders whichleads me to ignition ,cant be coil or points ,rotor button is new and so is the cap and leads

does it sound like something spark plugs would do ?? its normaly realy easy to start aswell
cheers

Plugs won't do that unless they get fouled. Via oil or carbon or overheated, which you should be able to see.

So the symptoms are:
* Hard starting
* wont idle right ,idles low or dies

Have you checked the Dwell angle?

no i havnt ,that might be worst checking!

so if the plugs become overheated they can become faulty? cos i got it abit hot a while ago while doing a burnout

Yes, overheating in the sense of glazing the porcelain.

thanks dd ! hopefully that fixes this thing ,carbed a series motors are awesome but when this happens its annoying !

still at least its a simple enough engine to figure most problems out on

cheers

when I was messing with tuning my Mukuni's on my 75 kawasaki H1 (3 cyl, 2 stroke) to figure out if its running properly I did some plug "chop" tests. Ths is a good way to determine rich / lean runnnig conditions - might be helpful....

http://kawtriple.com/mraxl/carb/plugchop.htm