If i dont use resistor caps...

[Guest]

then what spark plugs should i use?

1981 gs750e with dyna S ignition, 3ohm coils. Switched out dynas spark plug wires with some new NGK wires for my Subaru i had laying around. Bike started and ran really well before, battery was low and i took the carbs off to rejet, so i figured that low voltage+empty carbs was causing starting issues. But then after charging the battery and trying to start it again, all i got was a cough and sputter. Then i realized that the only thing that changed from before was the carbon fiber on the tank, and the plug wires,... which dont have resistors built in.. what do y'all think?

Havent tested the "before wires" again yet, not married to the NGK wires.... just liked the ease of serviceability with them, which is the whole focus behind the build in the first place.

[OldVet66]

Get a nice set of Dyna 8mm suppression wires. They don't cost much probably under $20.00.

[Nessism]

You will be fine if you use suppression wires with non resistor caps.

[60ratrod]

I never used the resistor caps with dyna coils and copper core wires on both bikes. They both ran fine

[tkent02]

It doesn't matter. Nobody listens to AM radios anymore anyway.

[TeamNeal]

Well see guys, the problem IS my AM radio........he he

[jabcb]

For Suzuki two strokes, I use either resistor caps or resistor plugs.
Not sure what plug your bike uses. Something an NGK BR8EIX, which has a 5K resistor.


Check the websites for your local auto parts stores. They are likely to have good prices if they stock the plug you need.

[Joe H]

I always thought the only reason to use resistor caps or plugs was to eliminate RF, yes for AM radio, but also for anything with a processor that isn't shielded. It can muck up your timing in situations like that. I don't think the Dyna S will be affected by that, but I don't know what other electronics on the bike it may affect.
I can't imagine why an old suzy 2 stroke would need resistor caps or plugs except the IEX (iridium plugs) don't foul nearly as much and produce a spark that can get thru a bit more of a rich mix or a less turbulent mix better.

[trippivot]

did you possibly mix up the wire positions 1/4,, 2/3 - no start ,, crank and crank the starter motor and then a loud backfire bang is classic mixing of the coils

dyna suggests the suppression wires - and I always have used them but it is not something that will prevent your bike from running.

and I don't double resist as in resistor plug and resistor cap. There are many reasons but mainly it is to clean a shaggy wild spark to make a precise timed ignition event

[Who Dat?]

It is my understanding that there are three places you can have resistance/suppression:
1. spark plugs
2. plug caps
3. wires

For the elimination (OK, 'serious reduction') of RFI (radio frequency interference), you need one of those three items. Does not really matter which one you have, but also make sure it's ONLY one.

[jabcb]

I always thought the only reason to use resistor caps or plugs was to eliminate RF, yes for AM radio, but also for anything with a processor that isn't shielded. It can muck up your timing in situations like that. I don't think the Dyna S will be affected by that, but I don't know what other electronics on the bike it may affect.
I can't imagine why an old suzy 2 stroke would need resistor caps or plugs except the IEX (iridium plugs) don't foul nearly as much and produce a spark that can get thru a bit more of a rich mix or a less turbulent mix better.

Back in the 70s, Suzuki two strokes were sold with resistor caps & non-resistor plugs.

[Grimly]

It is my understanding that there are three places you can have resistance/suppression:
1. spark plugs
2. plug caps
3. wires

For the elimination (OK, 'serious reduction') of RFI (radio frequency interference), you need one of those three items. Does not really matter which one you have, but also make sure it's ONLY one.

Depends on the total resistance required. The XJ9 needs a total of 10Kohm per wire, so that means a 5K plug + 5K cap (or a 10K cap on its own, much harder to get hold of).

Back in the 70s, Suzuki two strokes were sold with resistor caps & non-resistor plugs.

Nearly everything was.

[Gorminrider]

You will be fine if you use suppression wires with non resistor caps.

Hmmmm, maybe, but suppression wires have "resistance" based on length.
so A Good Reason to use suppression caps instead, is that the plug leads can be varying lengths without affecting the "resistance"...Plus, to get the same "resistance" as the stock caps (or at least an "effective" R) , these suppression leads may be quite long , which'll look a little odd. The shortest lead in your car may give an idea of minimum base point for suppression...?

[Datsa Noydb]

Depends on the total resistance required. The XJ9 needs a total of 10Kohm per wire, so that means a 5K plug + 5K cap (or a 10K cap on its own, much harder to get hold of.

Actually, since each circuit consists of TWO spark plugs, TWO caps and TWO wires, with the coil in the center, you DO have your 10K with just the 5K resistor caps.

[Grimly]

Actually, since each circuit consists of TWO spark plugs, TWO caps and TWO wires, with the coil in the center, you DO have your 10K with just the 5K resistor caps.

No, it doesn't - I was sceptical at first and double checked this. It needs 10K PER lead, for a total of ~32K including coil secondary of around 11K-ish. I'd suppose Yamaha specced this to avoid problems with the TCI unit. Some of the other XJs are more conventional, with 5K per lead.