resister caps
 

hi there guys im having some ignition problems with my 1985 43f , i think its the ignition switch so going to get a new one, while checking things the plug is a NGK DPR8EA-9 but the NGK plug cap has no markings to say it is a resister cap will check this with a ohms meter , do i need a resister cap and a resister plug , each has 5k ohms (5000) so both would be 10,000 ohms . so is 5k ohms ok or do i need 10k . from what i know the more ohms resistance the weaker the spark , but i have just fitted a new aftermarket cdi to a suzuki gsf 400 bandit and the leaflet seid both cap and plug MUST be supressed to protect the cdi . your views on the matter guys , the plug cap i dont think is my ignition problem but am going to fit a new one . zigzag

Hi zigzag.

I bought an ngk plug cap with 5k resistance. I didnt realise it at the the time it was 5k .( The original on mine was 10.5k)I fitted it and it did work. (Started and ran okay) i didnt leave it on though as it wasnt the cause of my problems so i refitted the oem one. I should say mine is a 4pt 2003 model

Bill

I always understood either cap or plug (or leads) but not both, and certainly not all three. I stand to be corrected but put resister plugs in one of my bikes with resister caps and it misfires to the point where it hardly runs.

hi guys ive measuered the old cap and strangly got 5800 ohms although its a 5k cap . i had a new one in my xt box of bits this one is 4800 not 5k so i fitted this so will see how things go , like i seid the cap is not part of my running problems but a new one can only help , thanks for your comments guys zigzag

"lectric!"
 

resistance in series is additive, E or volts divided by Resistance equals Amps.

without getting too deep into physics, lets just say that coil/resistance circuits behave diferently than a plain resitance circuit.... apples and oranges really, I=V/R applies only to a degree... voltage rise and spark duration (time wise) are much more improtant than absolute current.

in more practical terms, modern systems are designed to run 10-15K ohms resistance, i.e. R plugs + 5-10k ohm caps.

there's a good chance to get more misfries form running with 0 ohns caps rather than 5-10K, as spark duration gets shorter, so more hit and miss ign.