Spitfire Multispark

[Straw Bear]

I saw one of the Spitfire Multispark on fleabay which is fitted to HT lead and supposed to improve starting or in my case stop fouling plugs with increased pulses to spark plug. Are they worth buying or just another gimmick?

[AWJDThumper]

I think the consensus seems to be more placebo effect than real benefit on coil ignition systems. Multiple sparks are only really a benefit for electronic ignition systems where each spark is very short compared with the long spark in a coil ignition system. For the latter, extra sparks are probably of dubious benefit.

[Mike Farmer]

 

I put four of them on an ancient tractor that was not running very and got to say that once they were fitted it still wasn't running very well

Mike

[DerekAnderson8]

I put four of them on an ancient tractor that was not running very and got to say that once they were fitted it still wasn't running very well

Mike

At least you could rule out the ignition then Mike!



derek

[Mike Farmer]

 
Yo!!!
Mike

[Straw Bear]

Ok thanks guys for the posts but why do I keep fouling plugs on the left hand cylinder with only one monobloc carb fitted?

[Mike Farmer]

 

Oil burning or broken ring or Mistimed on that side or Wrong heat range of plugs or general wear in the valve stems/guides.

Mike

[DerekAnderson8]

need more info, i am guessing plug is sooty black? what colour is other one?

Does it run ok is it smoky on that side query blue smoke?

cheers

derek

[DerekAnderson8]

snap!

[Straw Bear]

The bike runs fine no noises, no smoke but when I use again after a run the left hand cylinder coughs and splutters but when change plug runs great. The colour of plug is black but opposite cylinder is proper colour. Not very up with things im afraid so grateful if point me in right direction....

[AWJDThumper]

Is that dry black indicating a rich mixture, or oily black meaning it is burning oil on that cylinder? It's difficult on a single carb engine to see how one cylinder could be running with the correct mixture and the other one is running very rich. If burning oil on one side is not the issue, the only thing I can think of is there might be a problem with a weak spark and incomplete combustion on one side.

[Straw Bear]

It is dry black so I will try the weak spark many thanks :-)

[JulianS]

Worth shining a small torch through the spark plug holes and observing the piston crowns, chances are that you will see the left piston crown is wet. If it is then careful use of a cotton bud on the crown will tell you if it is petrol or oil and will guide you on what you may need to do.

[AWJDThumper]

I would check the quality of the spark for each cylinder by connecting up a spark plug to each HT cap with its thread grounded against the bare metal of the engine. If you get strong healthy sparks on both sides then the ignition system is probably not the cause of your problem. In this case, it would be worth doing a compression test on both cylinders which should show if you've got a problem with the valves or rings on one side.

[Straw Bear]

Thanks again