Resistor plugs

[Zane]

I PM'ed Condor about a spark related issue and I posed the question to him as to why it is necessary to have a resistor sparkplug cap and a resistor sparkplug. Answer me this question, aren't resistor plugs primarily used to supress electric pulses from interfering with a radio? Yes ,Ventures do have a radio, but isn't the primary reason for owning a motorcycle to ride it and not listen to the c@#p on a radio. Any comments, suggestions, and/or helpful advice? Condor mentioned that he thought that VGoose had posted on this subject at one time. Soooo.....

Thanks all

[escheue]

You would be hard pressed to find non resistor plugs. I removed the resistors from the plug wires and it eliminated rough idle and stalling at idle without affecting the radio at all.

[Snaggletooth]

The NGK DP8EA-9 is the non-resistor plug for the 1st gens. Pretty common actually. Most the dealers and independent shops around here carry them in stock. About $12.00 a set.

 

I gap mine at .035 and they burn nice and great starts.

 

Mike

[Condor]

I PM'ed Condor about a spark related issue and I posed the question to him as to why it is necessary to have a resistor sparkplug cap and a resistor sparkplug. Condor mentioned that he thought that VGoose had posted on this subject at one time. Soooo.....

Thanks all

 

Yep I feigned ignorance.....

[MikeWa]

It's not just radios. Non resistor plugs or wires can drive integrated circuits and computers nuts. And not just on your bike. They can also interfere with those around you. Most ignition systems actually operate better with resistor plugs so do yourself and those around you a favor and use the resistor plugs.

Mike

[dingy]

The NGK DP8EA-9 is the non-resistor plug for the 1st gens. Pretty common actually. Most the dealers and independent shops around here carry them in stock. About $12.00 a set.

 

I gap mine at .035 and they burn nice and great starts.

 

Mike

 

The service manual calls for a DPR8EA-9 NGK plug. This is a resistor plug. It is the same call out in the 83-85, 86-93 & The RSV SM's.

 

See attached NGK chart.

 

I can't think of an obvious reason why a non-resistor plug would hurt the bike. The TCI would be, for the most part, isolated from the plug/wire total resistance via the primary/secondary's in the coil.

 

The thought that does comes to mind is that the effect of resistance in any series circuit is to reduce the current flow & cause a voltage drop across the resistance. Since the plug resistance is back to back with the cap's resistance, there seems to be little electrical benefit to having two separate resistors.

 

When the primary coil field collapses at the point the TCI interrupts the 12v- going to it, there then is a highly amplified build up energy in the secondary coil field as it expands. As this energy climbs past a required threshold, the result is the voltage potential difference causes the spark plug to arc over to ground in order bleed off this energy. As a result of this extremely rapid bleed off in the secondary, its field then collapses and will cause an inverse spike back to the primary coil. I am totally speculating here in that maybe Yamaha wanted the amount of resistance that is obtained from using the two resistors to somewhat dampen the resulting current outrush or limit the voltage potential difference, from the secondary. This would have the effect of then possibly dampening the bounce in the primary coil which would then be applied to the TCI.

 

There could possibly design intent built into the TCI to accommodate this. Otherwise, from a manufacturing cost reduction stand point, it makes little sense to put in a more costly resistor plug wire. The cost of a resistor vs non resistor plug is probably insignificant.

 

All this except the 1st two paragraphs have no basis in reality though.

 

 

Gary

[dingy]

The NGK DP8EA-9 is the non-resistor plug for the 1st gens. Pretty common actually. Most the dealers and independent shops around here carry them in stock. About $12.00 a set.

 

I gap mine at .035 and they burn nice and great starts.

 

Mike

 

 

Could your use of the non-resistor plug be the root cause of your short life of the plugs?

 

Gary

[Snaggletooth]

Could your use of the non-resistor plug be the root cause of your short life of the plugs?

 

Gary

 

More than likely not. I had the same issue with the DPR8EA-9's from the time I got the bike running and then the same since the change to the DP8EA's last year.

 

The first couple of years I didn't really notice it as I was still tinkering with the bike and not riding as much as I have this year. I went through 3 sets of plugs from fouling the first summer. Then the carb rebuild and that cleared up. After that I changed plugs each spring as SOP and never noticed any problem.

 

But this summer, the bike has ridden EVERY day and run long and hard on the weekends so the miles are rolling. As soon as I change plugs to new ones she's back to top of her game.

 

So I think it's the fuel mix as Goose suggested. If nothing else, the problem is consistant.

 

As I removed the amp to the sound system I'm not concerned with interference from the non resistor plugs. I had some issues with interference to the digital camera I installed last year and blamed it on the non-resistor plugs. Turned out not to be the problem and got the signal cleaned up.

 

Mike