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Spark plug resistor.

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I removed the resistor out of the plug wire and I beleive that is probably the best modification I have done. Quicker engine reponse, easier starting, and better fuel mileage. I recommend doing this to your bike!

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I removed the resistor out of the plug wire and I beleive that is probably the best modification I have done. Quicker engine reponse, easier starting, and better fuel mileage. I recommend doing this to your bike!

How? I understand better response and starting, but how does burn less gas? Same amount of air comes in, same amount is sucked from the carb.

The mod has been good so far for me, but better fuel mileage seems a bit far fetched.

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Yes, I noticed the same thing! I especially like the easier starting.:applause:

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yep, i second those motions! did the mod to my bike.starts easier and better low end throttle response.:lol::eek::lol::applause:

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I don't know if it is getting more miles to the gallon, however I don't have to give it full throttle for the power I want, so in turn I don't use as much fuel. If that makes any since.

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Ahhh, so because of the change in the powerband, you find the power you need at a lower RPM and burn less gas. Makes sense.

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Those of you who have noticed large performance gains with this mod, if you still have the old resistor and have access to an ohmmeter, would you mind measuring the resistor and posting your results?

Thanks,

-Bob

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TMX,

I just happened to perform this mod to my XR4 yesterday but I haven't tested it out. I cut up a stainless steel bolt, ground the ends smooth, and applied a dab of anti-oxidant compound on both ends.

I saved the resistor just in case I need to reverse the mod AND I happened to measure it with my digital multimeter. It read 5000 ohms.

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I did this 'mod' years ago to my 250 (noticed no difference at all in performance). I still have the resistor in my parts bin and measured

it at 4.79Kohms.

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the resistor is about 3k ohms

how many ohms is the steel or stainless steel bolt that we are putting in the caps? i have done it and totally agree that it works . much better throttle response of the bottom end.

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how many ohms is the steel or stainless steel bolt that we are putting in the caps?

It's going to be very close to zero.

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I wonder if the varying results seen with this mod is due to jetting and 'tune' of the fuel system of the bike in question. I've seen write-ups on resistor vs no resistor and from what I understand the spark 'strength' and duration are affected by the resistor. Lower value of R means 'stronger' spark but at a shorter duration. As well, a higher value of R will give you a 'weaker' spark but for a longer duration.

I've also seen it mentioned that if there is contamination on the plug tip (such as unburned fuel maybe after a fall) a resistor will sometimes keep the plug from firing at all. This may account for the easier starting comments. Seems like getting rid of the R is a good way to go since we don't care about RF emissions on our bikes.

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It's going to be very close to zero.

yea, for all intents and purpouses. if in reality it had .25 ohms i'd be surprised.

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I'd be surprised if it were more than .01 ohms. A piece of conductive metal about 4mm. in diameter is bigger than any fuse I've ever used. And we certainly don't want to lose any power in our fuses when things are functioning correctly!

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My resistor measured about 5.5k Ohms.

I just cut off the end of a bolt and coated it in di-electric grease and threw her in there and worked like a charm.

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the resistor is in the rubber cap that goes over the spark plug.if you look in the end of the rubber cap you will see a bolt. unscrew it and out falls a bolt, a spring, and the other piece is the resistor. hope that helps.

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