Sparkplug Cap Resistor?

I removed my resistor as the plug has a resistor in it already. I think its safe to remove it because most plugs are resistor types.

I had heard in the past in another group that it was bad juju to run a resistor cap and resistor plug at the same time. But my bike came stock with both.....

I recently bought one of those directhits spark gizmos.

Spark, starting and performance seemed the same on my new bike (TW200) with a resistor cap and non resistor plug.

The spark seemed much brighter on my old bike (RV90) with a non resistor cap and plug. I haven't rode it around yet to see if it changed anything.

My uncle accidentally ran plug and cap resistors on his 72 trail 90 and it ran like poo. But it is a 6v bike made long ago.

:moon:

Edited by rm_hm25
Updating

Hmmmm, inquiring minds want to know. But I do know of a guy who may have the straight answer . I'll bend his ear. BTW I dont recall any outboard motors using resistors on their CDI. hmmmm

I found the old forum where I read about the bad juju...

What are Resistor Plugs? Well by now you might have realized that the major part of the resistance in the F Plug/Coil system is provided by the Plug Cap. Some bikes use Resistor Plugs, so another solution could be to just have a 0kohm Cap and Run Resistor Plugs in your bike, but not both!

* I realized I was running resistor plugs AND resistor caps. I changed to zero Ohm caps & MPG on my R80G/S went up about 10% when.

* NGK do make a resistor plug, the NGK DR8EA. The OEM cap was 1kohm. Substituting a 5kohm cap is probably OK. A 0kohm cap without using a resistor plug like the DR8EA is NOT OK. If you use anything (but) more than 5k, you'll probably get less spark than you would with 5k due to impedance mismatch. But using 10k would probably be just fine in practice. But for good fuel economy DON'T use both a resistor cap AND a resistor plug. In other words, I don't think it really matters all that much one way or the other as far as making the bike run. Economy might suffer slightly. But would you really notice?

* I may be way off base, but I thought the resistor in the stock plug caps performed the same function as an "R" type plug. True? If so, adding an "R" plug would simply be adding more resistance to the spark circuit. It probably wouldn't make much difference in how the bike runs if the resistance isn't too high (for a while I used a 5kohm NGK resistor in one of my plug caps when the stock resistor went bad -- and my '99 ran just fine). Bob#550 (Olympia WA)

http://faq.f650.com/FAQs/SparkPlugFAQ.htm

Edited by rm_hm25
Correcting Spelling

NGK's DPR8EA-9 is the factory plug for big RFVCs and it is a resistor type, so the factory configuration uses a resistor in the wire cap and the plug...

Al Baker once told me that removing the resistor was good for 200 more RPM. I never doubted him as he had done dyno testing. May be just a tale.

NGK's DPR8EA-9 is the factory plug for big RFVCs and it is a resistor type, so the factory configuration uses a resistor in the wire cap and the plug...

yup...i doubt the Honda engineers got it wrong :moon:

this link on the second page of this thread pretty much sums it up :smirk:

http://www.motorcycleproject.com/motorcycle/text/plugwiretech.html

specifically...

"The Effect of Electrical Backlash on Ignition Components

Second, on some offroad vehicles, resistive secondary components of a slightly different specification are present to reduce the electrical backlash that spark creates in the coil’s primary winding. This unwanted electrical feedback is harmful to the parts that drive the ignition system, particularly the ignition control modules (CDI boxes, igniters). Motocross bikes use resistive secondaries to protect the CDI boxes."

Al Baker once told me that removing the resistor was good for 200 more RPM. I never doubted him as he had done dyno testing. May be just a tale.

Dwight, ur refering to the XR600R correct?

it is possible that changing the resistance cud effect the the analog circuits rev limiter...but i've never seen a schematic for any of the XR's CDI...

...if i ever have one fail or get my hands on an extra CDI i will perform an autopsy :smirk:

sumome want to send me a failed CDI???

:cheers:

it is possible that changing the resistance cud effect the the analog circuits rev limiter...but i've never seen a schematic for any of the XR's CDI...

And you probably never will unless someone reverse-engineers one. They are potted in plastic not just for vibration resistance, but also to make them a PITA to take apart. They have proprietary electronics as well with no datasheets available outside of Honda's electronics engineering circles.

Besides that, I would go so far as to say that 99.9% of the big RFVCs out there have a power peak at least 1500rpm below the limiter and are well out of power by the time they hit it, so removing the resistor to get more won't do any good. The exception, of course, is built race engines...

Dwight, ur refering to the XR600R correct?

QUOTE]

I was refering to all XRs. At the time we were working on XR250s but I did the same mod on my XR600s too. All my XRs seemed to have a tad more top speed than other XRs I ran with. Not more power just a few more RPM when maxed out in high gear.

All my XRs seemed to have a tad more top speed than other XRs I ran with. Not more power just a few more RPM when maxed out in high gear.

...or maybe u were just crazy enough and had the skillz to keep it pinned :smirk:

:moon:

:cheers:

With all the recalls lately on a multitude of car makers, I wonder what engineers got right?

The big auto makers spend way more on engineering & testing then bike makers I would imagine.

I work on new $200,000+ yachts and see where the makers or just the workers cut corners all the time. Don't get me started on "no sand" bottom paint primer that gets used on new boats.

How much research and development went into my new 09 tw?

From what I can tell the design is mostly unchanged for the last 10+ years. Surely in that time there must be something more efficient they might have upgraded.

What have they done? They decided to change the carb (and run way lean), get rid of the kick starter and change the paint. They did have a rear shock recall for I think pre 1997 models. The stock chain and sprockets are worthy of a dollar store.

I'd love tubeless tires, a fuel tank bigger then 1.8 gallons and one more gear. Don't get me wrong I love the bike and I'll love it more after I add 500 bucks of farkles. What really sucks is all the truly great aftermarket parts for it are only sold in Asia.

There are lots of bike oops out there. (mostly street)

http://www.motorcyclistonline.com/motorcycle_recalls/index.html

http://motorcycleviews.com/recalls/motorcyclerecalls.htm

http://www.thumpertalk.com/forum/archive/index.php/t-640057.html

XR600 Problems I have seen and read about are

Rear hub bearings loose at 6-8,000 miles.

Timing-chain tensioner toast at 10-12,000 miles

Third gear. It usually starts going out at about 15-18,000 off-road miles. Many hard-riding racers will tell you even sooner.

Only bad things I've heard about cr500's were they often would be a bastard to start. But once they were goin hang the hell on for one great ride.

Ok Ok back on to the thread topic.

I'm still on the fence about the whole resistor issue. Removing it did make the spark brighter but the ole butt dyno didn't notice anything and it started and idled the same.

The directhits wonder spark gizmo has been demoted to my wood chipper (I still don't notice a difference). Any members in the Tacoma area are welcome to borrow the thing (not the chipper).

Edited by rm_hm25
fixing my crappy spelling

And yet the bikes that this (old) thread applies to have had no recalls listed in either of those links.

Here was compelling post for getting rid of the resistor plugs.

Posted by Mikeee P

I remember when resistor plugs started becoming mandatory on off-road bikes. We never understood why but were told the CDI's had to have them etc, etc...

I was talking to one of the bigwigs at NGK one day and said "Hey, what's the deal with resistor plugs. Why are they necessary?" He didn't answer for a while and then said "Once the spark gets to the plug, do you think it's going to turn around and go back into the CDI?" I of course replied "No..." and then waited for his answer... and waited... and waited... then I said "So basically modern motocross bikes don't need a resistor plug?" He basically replied that as long as the manufactures want them, we'll make them. But the spark isn't going to go to the cap, do a u-turn and come back to the CDI. So he was implying that bikes don't need resistor plugs for the CDI's.

I've heard numerous debates after mentioning this to people - but I always go back to what the bigwig from NGK implied to me... that the electricty doesn't do a U-Turn and go back and tear up the CDI, so the thought that a resistor AFTER the CDI will keep the CDI safe is ridiculous. It's like standing in front of a loaded gun, and putting a bulletproof vest behind you. Too late. So if they were worried about the CDI getting too much juice, you'd think the resistor would be before the CDI(???). I realize the CDI makes a lot more voltage than the stator does, but it's one of those things that makes ya go "HMmmmm???" - MP

----------------------

And a post to just leave the stock setup alone

Originally Posted by Mike38

I took apart the spark plug cap on my CRF150 after reading that thread. I didn't find a resistor in it.

Does removing a resistor from the cap make for a performance improvement? You bet it does! Is it possible to cause damage to the engine and/or electronics? It could!

In electronics a resistor is used to reduce the voltage applied to a circuit. So by removing an existing resistor, you will increase the voltage at the spark plug gap.

Imagine water flowing through a pipe. If we make the pipe narrow (a resistor) then this will restrict the flow of water (electricity). If we force the water (current) through the narrow gap by increasing the pressure (voltage) then energy will be bled off in the form of heat. There is a significant difference in pressure (voltage) above and below the restriction.

Now, if the ignition system on a motorcycle is designed at the factory to have a resistor in the spark plug cap, the voltage (pressure) drop is compensated for, before the resistor, so the correct / ideal voltage will be present at the spark plug gap. Could removing the resistor cause excessive voltage (pressure) at the spark plug? Yes it could.

My advice, if it has a resistor, leave it there! Same goes if the OEM calls for a resistor spark plug. Replace with OEM parts, or at least use a colder plug.

The only time removing the resistor may be safe would be on an old bike (15 to 20 years) with a weak ignition system.

The above was written by an Industrial Electrician (That would be me). Precede with any modifications at your own risk.

It's like having two supervisors that want you to do one job two different ways :thumbsup:

After reading all the reply's I'm convinced that Honda could have designed a reliable CDI ignition without the said resistor. That said, both of my XR's still have them in place BUT if either of them suddenly fail to get a spark, the 1st thing I'm gonna check is that stupid resistor. I don't mean to sound like a conspiracy theorist here but there's not a sparkplug company in the world that can't (cheaply) design the Ohm value into a sparkplug that would eliminate the need for the resistor. In other words, if one fails, 90% of the owners would most likely be completely at their wits ends. And their only option.........?

The Dealership!!:thumbsup:

Don't know how much this translates, but if a 4ohm speaker is used on amplifier only designed for 8ohm, the amp will overheat and burn up, not designed for that low of a resistance.

I would think the CDI and coil are designed to have a certain amount of resistance to operate properly. Reducing resistance may not be benificial to the systems longevity.

Manufactuers have many hours R&D in their products, not to mention some intellegent people designing the components to meet every aspect of performance and government regulation possible with cost in mind. Cost and regulations do cause some degrading in the designers origional vision of the product, but it is hard to beat factory longevity. A lot of owner tinkering and aftermarket products decrease longevity, for some slight or not so slight increase in power.

Owners looking for "free" upgrades by removing or disabling factory installed devices is nothing new. Forget free, it usually ends up costing more after failure. One change in a system usually requires a change elsewhere to function properly, system is the key word.

I can think of one practically free upgrade for more all-around motorcycle performance increase with changing only one thing on the motorcycle, it just requires those with extra heft to save money on groceries. :thumbsup:

Owners looking for "free" upgrades by removing or disabling factory installed devices is nothing new. Forget free, it usually ends up costing more after failure. One change in a system usually requires a change elsewhere to function properly, system is the key word.

I will respectfully disagree with you here!:thumbsup:

[quote name=

I can think of one practically free upgrade for more all-around motorcycle performance increase with changing only one thing on the motorcycle, it just requires those with extra heft to save money on groceries. :thumbsup:[/quote]

I hear you there, I bet all of my bikes would enjoy the upgrade of me getting thinner :ride: I'm glad they don't chat with each other yet.

Do the bike makers make our ignitions just to get the job done for the cheapest amount of money or is there room for improvement somewhere?

I wonder what 2 and four stroke high performance outboards have for cap and plugs?

Edited by rm_hm25
uh huh huh huh

I think it's funny that people are just about as strongly opinionated on removing the coil wire resistor as they are about running 650Rs without a thermostat. Now we just need to throw in some "what oil is best" and "how to break-in an engine" discussion. :thumbsup:

Here was compelling post for getting rid of the resistor plugs.

Posted by Mikeee P

I remember when resistor plugs started becoming mandatory on off-road bikes. We never understood why but were told the CDI's had to have them etc, etc...

I was talking to one of the bigwigs at NGK one day and said "Hey, what's the deal with resistor plugs. Why are they necessary?" He didn't answer for a while and then said "Once the spark gets to the plug, do you think it's going to turn around and go back into the CDI?" I of course replied "No..." and then waited for his answer... and waited... and waited... then I said "So basically modern motocross bikes don't need a resistor plug?" He basically replied that as long as the manufactures want them, we'll make them. But the spark isn't going to go to the cap, do a u-turn and come back to the CDI. So he was implying that bikes don't need resistor plugs for the CDI's.

I've heard numerous debates after mentioning this to people - but I always go back to what the bigwig from NGK implied to me... that the electricty doesn't do a U-Turn and go back and tear up the CDI, so the thought that a resistor AFTER the CDI will keep the CDI safe is ridiculous. It's like standing in front of a loaded gun, and putting a bulletproof vest behind you. Too late. So if they were worried about the CDI getting too much juice, you'd think the resistor would be before the CDI(???). I realize the CDI makes a lot more voltage than the stator does, but it's one of those things that makes ya go "HMmmmm???" - MP

the above is the biggest bunch of bullchit i've seen in a LONG time...:lol:

salesman bullchit (i wus one for over twenty years)...and he's definately NOT an electrical engineer(and yes my EE diploma is still hanging on my wall) :thumbsup:

do wut chu want but u might want to carry and extra CDI :ride:

:lol:

http://en.wikipedia.org/wiki/RC_circuit

I think it's funny that people are just about as strongly opinionated on removing the coil wire resistor as they are about running 650Rs without a thermostat. Now we just need to throw in some "what oil is best" and "how to break-in an engine" discussion. :thumbsup:

:ride::lol: Amen brother :lol::lol:

I'll bite: Take out the stat, remove the resistor and fill 'er up with canola oil...

drill a few random lightening holes in the flywheel to keep it interesting:smirk:

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