DP9EA-9

[fjbiker84]

I went by the local motorcycle store - Del Amo Motorsports - today to get a few things for the bike and decided to get a new set of spark plugs.  I've always run NGK DP8EA-9 or DPR8EA-9 in the bike since I've owned it.  To my surprise the store didn't have them in stock but the service manager insisted that the DP9EA-9 would work fine.  He said it was a little "colder" but otherwise the same.  I went ahead and bought them but after checking my Clymer Service Manual it does't list this plug.  Should I just return them and get the DP8 or is this pretty much the same thing?

[Schurkey]

He said it was a little "colder" but otherwise the same.

Same plug, one heat range colder.

Do you ride fast/hard?  What do your old plugs look like?

Wild Guess:  You should get the same heat range that's worked for you previously.

[fjbiker84]

I don't ride that hard.  Lots of city traffic wherever I go.  Plugs look a little black after 1000 miles which is the interval I take them out and clean.  Replace the plugs every 2-3000 miles.  I'm guessing with my situation colder plugs are not better.

[ribbert]

I don't ride that hard.  Lots of city traffic wherever I go.  Plugs look a little black after 1000 miles which is the interval I take them out and clean.  Replace the plugs every 2-3000 miles.  I'm guessing with my situation colder plugs are not better.

Just on the point of plug change intervals, you're about my vintage and yes, we used to clean and test plugs (on one of these beauties)...



.....every 2000 miles and replace them every 6000 miles. Times have changed, replacement intervals are now about ten fold the rate you are changing yours and no one cleans them anymore.

I change my plugs every 50,000km on the FJ and they never come out in between. When I change them, there is absolutely no improvement in starting or performance and a visual inspection even shows them to still be in good condition. That's on cheap standard plugs, iridium plugs for example will last 100k.

You should by now have a drawer full of barely used plugs to reinstall.

Noel

[fjbiker84]

I have the original owners manual in addition to the service manual for the FJ and I'm pretty sure one of those (or maybe both) specify a replacement interval of something like 5 or 6 thousand miles.  I'll try getting more miles between changes and see if there is any noticeable difference in performance.   

[ribbert]

I have the original owners manual in addition to the service manual for the FJ and I'm pretty sure one of those (or maybe both) specify a replacement interval of something like 5 or 6 thousand miles.  I'll try getting more miles between changes and see if there is any noticeable difference in performance.  

I don't know what the manual says but that sort of information tends to get carried over to each new edition for the duration and that would take it back to the early eighties anyway. Tyres, lubricants, brake pads, chains, lighting, ignition systems, batteries, spark plugs, the materials from which flexible components are made etc have all improved in leaps and bounds since our bikes were made and the life span and performance of them changed accordingly.

As I said, 6000 miles used to be the change interval on most vehicles and by that time were often noticebly breaking down, but that was a long time ago.

Noel

[FJ_Hooligan]

I recently bought my daughter a 2001 Jeep Cherokee Sport with 180Kmiles on it. 

I think the plugs were the original equipment. 

The tip of the electrode was an almost imperceptible nub,
The ground strap was paper thin
The gap was >0.090 inches, spec is 0.035 inches

Yet the engine ran like a top.

I got around to changing the plugs in my wife's '09 Suburban at 120Kmiles.  Aside from some corrosion on the outside, the plugs looked good enough to reinstall.

I need to look it up but I can't remember the last time I changed plugs on my FJ.  The criterion I typically use is when the outside of the plug get rusty and corroded looking I change them.  Probably 10 to 12Kmiles.

On my old Hodaka 100cc, a new plug always made a significant boost in performance.  The FJ doesn't seem to mind.

Same with my FZ1, I changed the plugs when I checked/adjusted the valves at 38Kmiles. 

[gumby302ho]

I don't ride that hard.  Lots of city traffic wherever I go.  Plugs look a little black after 1000 miles which is the interval I take them out and clean.  Replace the plugs every 2-3000 miles.  I'm guessing with my situation colder plugs are not better.

Just on the point of plug change intervals, you're about my vintage and yes, we used to clean and test plugs (on one of these beauties)...



.....every 2000 miles and replace them every 6000 miles. Times have changed, replacement intervals are now about ten fold the rate you are changing yours and no one cleans them anymore.

I change my plugs every 50,000km on the FJ and they never come out in between. When I change them, there is absolutely no improvement in starting or performance and a visual inspection even shows them to still be in good condition. That's on cheap standard plugs, iridium plugs for example will last 100k.

You should by now have a drawer full of barely used plugs to reinstall.

Noel
  I agree with Noel, plugs last a very long time and always got a kick out of people as soon as there vehicle starts to act up the first thing they do is change out the plugs rather then inspect them first, clean them up and check the gap. I would like to know for example why my old chevy ran like shit with champion spark plugs vrs running proper with ac delco's( resistance is futile) Dont ever run champions in a chev and always run NGK in Japanese. Just sayin!

[Country Joe]

I just checked the Haynes manual for spark plug maintenance. It calls for removal, cleaning and regapping at 4,000 miles and replacement at 8,000 miles. Sounds very conservative to me.

[racerrad8]

Not sure why you would want to go colder unless you are building higher combustion temperatures.

If they are showing a little black, that means the bike is running a little rich. The colder plug will amplify the possibility of fouling the plug(s).
We had more than 100K miles on Ramos FJ using these NGK Iridum spark plugs. I know it got a new set at the rebuild, so not sure what the current mileage is.

There should be no reason to change them every 2-3K unless there are carb/engine issues that dictate the necessity to replace.

Here are a couple of NGK charts about heat range.




Randy - RPM

[Alf]

I use DP9EA-9 BUT

1.- I do a lot of hard riding in very tight and slow roads, where the rpm go up and the speed is not so much between curves
2.- The minimun average temperature in Tenerife is around 20ºC
3.- My FJ has the relay trick done (hotter spark), perfect emulsion tubes (with around 50.000 km. these get ovaled, so the bike runs rich) and is carefully carburated and maintained

Anyway, I use my FJ everyday and I've never had a problem with the colder plug

BUT

In Madrid, my friends, with cold winters and with well cared and maintained FJs too but without the relay trick done, my friends have had problems and they use DP8 plugs

I hope it helps. Regards

Alf

[fjbiker84]

Good info - thanks!  I think the thing to do is return the colder plugs and go with the iridium plugs from RPM next time I put an order together. 

[Schurkey]

I won't buy expensive (Iridium, Platinum) spark plugs for any vehicle that doesn't have feedback fuel injection (includes O2 sensor.)

Unleaded fuel, feedback FI, and "highway" gearing (on cars and light trucks this includes overdrive transmissions) have made spark plugs almost--not quite--"life of the vehicle" items.  My Trailblazer got the plugs pulled at 90K, and they looked so perfect that even though I'd already bought replacement plugs, I tightened the gaps about .002, applied anti-seize to the threads, and screwed the original plugs back in.  The original plugs didn't get replaced until about 160K, and they looked worn but not horrible even then.  Amazing, to me.

A carbureted bike has very different operating conditions, though.  There's a larger range of cylinder pressure, there's a larger range of operating RPM, the ignition systems are often weaker, and with two of the four plugs firing in reverse polarity compared to coil-on-plug or distributor-equipped vehicles.

My point is, with less-precise fuel control, the motorcycle plug is more likely to foul than to wear the electrodes.  No sense installing 100,000-mile electrodes if the plug has deposits in 8,000 or 15,000 miles.