Spark plug types with points ignition

[kstoo]

I am trouble-shooting some cranky cold weather from Gilera, my 1980 R100, and I suspect the carb rebuild / adjustments that I just made. My question here is I am also wondering if there is something wrong with the spark plugs that I just replaced. I replaced the ancient Bosch W5D with the NGK cross referenced plug from **** Auto Parts. Is there any problems that you know of with using modern spark plugs from the auto parts computer cross reference? What should I be using?

[sumran]

What is the number of the plugs they gave you? Are they resistor type?

[flash412]

Get rid of the metal plug caps. Replace them with NGK.

[kstoo]

BP7ES
I can't tell with confidence if these are resistor types or not. NGK and snowbum have both cross referenced them.
metal plug caps, replace them with NGK. What part number? info?

[spof650]

http://www.ngk.com/more_info.asp?AAIA=&pid=3832



clicky da linky

[sumran]

If you used Snowbum's cross reference you should be fine. The auto parts store will sometimes give you the resistor type.

[kstoo]

thanks, that link does say non-resistor. That was after I thought to go out to the garage and measure the resistance of the stinking spark plug. OK that is not the problem.

[kstoo]

Get rid of the metal plug caps. Replace them with NGK.

what is the story about these 'metal plug caps'? Why are NGK better? With NGK what?

[flash412]

what is the story about these 'metal plug caps'? Why are NGK better? With NGK what?Measure the resistance of the metal caps. They SHOULD be 1k. I bet they're more than fifty times that. NGK caps are plastic and do not let water in. The contacts will not corrode. They solve all manner of issues. Get 5k NGK caps (XD05F) and NON-resistor plugs.

[Rod Sheridan]

Replace the old metal caps, however for points ignition, I would use the 1,000 ohm (1K) NKG caps...............Regards, Rod.

[benway]

I agree with the 1k caps for points

however,

I think that post 78 [/7 on] , the bikes came stock with the fat black rubber plug/wire, which is think is actually 5k.

Either way, I don't think it will make much difference. Plug cap resistance is mostly about RF suppression and does not affect the ability to fire/spark.

[as the resistance is actually infinitely high before the spark jumps, the 1k/5k doesnt make much difference]

what it affects is the duration of the spark and shape of the decay/wave, after.

5k is mostly to stop RF messing with electronic ignition components.

hope that helps

[kstoo]

yes indeedy that helps... good information.
I do have the black caps and agree that 5k ohm is overkill for points ignition. thanks.

[flash412]

NGK offers only one plug cap with a 1K resistor. Since the Berus normally corrode to 5K within a year or two (and 50k - 5M in 5-10 years), the difference is minimal. If it REALLY bothers you, buy a pair of NGKs that are 1k and a pair that fit and swap out the 5k resistors in the ones that fit with the 1k resistors.

OBTW... the XD05F is a 120° cap, not a 90° cap. Sorry about that. I don't have the other NGK part number handy. Google is your friend.

[lkchris]

Is there any problems that you know of with using modern spark plugs

Today's spark plugs are same as 1970s spark plugs except Bosch went to copper core. Not much of a difference.

[kstoo]

Today's spark plugs are same as 1970s spark plugs except Bosch went to copper core. Not much of a difference.

"modern" meaning resistance, I guess. I was trying to find out, and I think I get it now, whether anything sold today was non-resistor. thanks for all the good information and discussion.