battery

Previously warren_long wrote:

can any onerecommend what type of plugs and battery for my 1973 850 commando with a boyer ignition

thanks warren

Hello Warren,

It really depends how much money you want to spend. The standard battery and plugs work fine with the boyer although I recommend that you make sure that you have plug caps without a suppressor fitted as you want to avoid having suppressors in both the spark plug and the plug cap. just check the plug gaps are not too big, most plugs come preset at 25 thou which is a big gap for the spark to bridge. If you set the gaps properly it gives the ignition circuit an easier time of it. If you still have the standard rectifier and zenor diode fitted I would change to a solid state regulator rectifier and junk the zenor or risk your lead acid battery boiling over and spoiling your chrome when they eventually fail. I prefer the modern gel type battery but they are more expensive. If you want to try the iridium spark plugs they are about 4 times the price of a standard Champion or NGK but I have tried them and personally I don't think they are 4 times better. The thing with the old boyers is that they need a full 12v in the battery or it sends the ignition timing all over the place, symptoms are poor starting and when it does fire up it will be as rough as a dog until the alternator can get some juice into the battery. So the most important thing is to make sure your charging system is tip top then look at the type of battery and plugs.

Regards,

Peter Austin

Can't fault Peter's reply. I have a Mk 3 850 Commando. The standard Champion plugs work just fine and since changing to a heavy duty gel battery (They tend to hold their charge better) there have been no starting or running issues, especially kicking back through low voltage.

I also found starting easier since I changed from SAE 40 oil to 20/50. If you don't already have it, I found a single carb conversion well worth it. I went from an average 45 mpg to 68 mpg with no noticeable loss of performance.