My Starfire ran beautifully, until one day it stopped suddenly. I ended up tracing the problem to the sparkplug, changed it for a new one and away she went. The problem is every so often this problem recurs and again I have to pop in a new plug. Cleaning the old one does not make any difference. Any idea what could be causing this problem. Other than that the bike runs very well and normally starts up first kick.
I think your problem might be cold fouling of the spark plug. If you are only cleaning the plug with a wire brush, this may not be sufficient. You really need an abrasive blast, to clean down inside the plug. I wonder if that might make your plugs work again?
Garages used to have a Champion Spark Plug Cleaner, but since plugs only cost 1/6d (well they did when I last bought one), they now just renew them and they threw all the abrasive cleaners away.
Cold fouling can also be caused by a weak spark or incorrect mixture. The best way to check the spark, is to invest in a Spark Gap Tester, or make one. You could just hold the HT lead about 5/16" away from the cylinder head, but it's difficult to hold it steady while kicking the engine over. This will indicate about 15,000 volts.
Are you using the correct heat range of plug? A hotter running plug may help to burn off any deposits. Maybe you could try a different make of plug?
Perhaps you could check the colour of the ceramic nose of the plug, (not the colour of the metal body to which the earth electrode is attached).
If you search on the internet, you will find websites showing the different colours and what they mean.
I hope this helps.
Good advice there
Btw a lot of cheap fake NGK plugs out there on ebay ;)
Just one more thing.
You might like to check the resistance between the white ceramic insulator nose and the centre electrode.
If it's over 10 ohms, the plug should be fine, but if it drops to 0 ohms, the plug may be fouled.
Hi,
The fact that the bike ran beautifully and then suddenly stopped when the problem occurred implies that it is something that changed very quickly. Has this all happened with the same fuel? If so it is possible that something is wrong with the fuel. If there is a contaminant in the fuel it may take bit of time for it to be deposited and baked on the plug like a hard clear coating. Hence, a new plug will work for a while until again the contaminant fouls the plug.
Try scraping one of the plugs and see if it works and then fouls again. Also, try some fresh fuel.
Dave.
Many thanks for the informative replies. Regarding the petrol. It is new, of the highest octane with an additive. The tank was cleaned out when I originally got the bike as initially I had fuel problems. The plug when removed showed a dark deposit, which I put down to the mixture being a little on the rich side. The exhaust was also a little smoky until she had run for a minute or so. It has a concentric carburettor and the bike has electronic ignition. When I tested the spark it was very strong but even after a clean with the wire brush she would not fire up. Popped in the new plug and away she went.
I did wonder about the plugs, 'just how good they were'. I am using the standard ones for the B25 B8ES but as I purchased those off the internet they may not be the best available. I see there is an upgrade to a BR8E1X. I may try one of those. I do remember the Champion plug cleaner, shame they are no longer around. I also notice that the cheaper ones on line say made in Japan. The more expensive 'Genuine' plug I spotted said made in France.
Anyway I shall work through your advice and see if I can improve things. Thanks again.
John.T
Hi,
I remember an issue with plugs being raised a while ago and it seems that some plugs are made with a porous ceramic insulator which if it gets wet with fuel will short out and not spark.
I think a 'C' in the number denotes this type of plug but you have used B8ES so should not be porous but may have been miss identified. I assume they are NGK.
Make sure they are not those plugs that have a porous ceramic insulator.
Dave.
Unless you source new old stock all plugs use unglazed insulators. With most vehicles being fuel injected with instant starting glazing is no.longer needed. I belive Brisk plugs are glazed and appear to be up to the job.
Many thanks for all the replies. At the moment the bike is running okay. And I have found an antiquated garage that has a plug cleaner. I shall get the old plugs cleaned and see if she will fire up using one of those. At the moment where ever I go I carry a new plug. 'Just in case'.
The B8EX is a cold type of sparkplug, so you might need a hotter one. I think the next hottest is the B6EX. The NGK range goes numerically downwards for hotter, but Champion go higher in number for hotter. My old B50 used the N4, but standard engines use N5, and only for oily engines would you require N8.
I did revive a fouled plug once by heating the end with a blowlamp, but the 'Green Plug Company' frowned upon this method... I'm not sure why, because ceramic can withstand really high temperatures.