Topic: Modifying spark plugs

[HondaMan]

Ok after today, I think it may have helped the top RPM a bit as well, clutch seems to be slipping again over 8000 rpm.
It was slipping at the beginning of the year, so I adjusted everything.
Had gone away after that, until now.

I took her for a canyon drive in provo canyon to american fork canyon.
Everything is fine, until 3rd and 4th gear at 8k+ rpm's.
1st and second though, no slippage at all.
Mabey just getting to the point where it takes so much more HP/torque to accelerate and the clutch can no longer hold it together.

The motor whirrs up to 10k, but the speedo SLLLLOOOOOOwly climbs up.
I haven't a place to get a 5th gear test at that RPM range....





Mabey it's just my clutch finally giving it's last days(still stocker/original plates), mabey it's just time for some heavier springs. Who knows.



l8r

Try springs first, if you have them, Soos. The clutch is losing oil and slipping: some more tension might improve the grip. Or, a plate (metal plate) might be warped. Both would act about the same.

[schneider419]

my question is when a plug is new, the center electrode is nice and sharp all the way around it's edge. as the plug wears, the spark goes to another sharp edge. if you remove half or more of the grounding electrode, are  you shorting the life span of the plugs usefullness? just a thought.
                             mike

[mystic_1]

and it's a GOOD thought.  Sparks like to jump off of pointy edges, not so much rounded shapes.  Soos stated earlier that his center electrode is becoming worn (rounded off) in just one area.  So, sounds to me like this mod results in the spark jumping from the same spots on the electrodes instead of wandering around the whole area at random, which is logical when you think about it.

Like any other mod, one has to weigh the benefits versus the drawbacks.

mystic_1

[Terry in Australia]

what are you doing flooring it when it was cold??  

I like to "torture test" my bike to simulate a idiot on it.

Ha ha, I nearly pisssed my pants reading that! 

[KeithB]

I don't know...but you would think that a company like NGK with years of experience in this field would have done something this simple if it works.
Just sayin'....

[HondaMan]

and it's a GOOD thought.  Sparks like to jump off of pointy edges, not so much rounded shapes.  Soos stated earlier that his center electrode is becoming worn (rounded off) in just one area.  So, sounds to me like this mod results in the spark jumping from the same spots on the electrodes instead of wandering around the whole area at random, which is logical when you think about it.

Like any other mod, one has to weigh the benefits versus the drawbacks.

mystic_1

The "fine wire" plugs of the 1980s were an attempt to make the center electrode 'always pointy' at the time. It worked well, except they wore off so fast that 10,000 miles was enough time to burn off the whole tip, back to the normal-sized portion of the electrode again.

I don't know...but you would think that a company like NGK with years of experience in this field would have done something this simple if it works.
Just sayin'....

They do: NGK is a subsidiary of ND Corporation. The parent company still markets the "U-groove" ground electrode, (X24ES-U and X22ES-U for these SOHC4 bikes) which yields two parallel sharp edges on the ground side to make the spark a little better for a little longer (and it works, try some!).

I have these plugs, from new to dating back to 1980. To refurb after cleaning, I flat-file the center electrode to sharpen those edges. On the U-groove portion, if I see a rounded edge appearing near the electrode, I bend out the arm a little and sharpen those edges with a modeler's file. They have a nice, fresh-plug feeling when reinstalled, which feels almost as good as new ones. Some of these old ones I have must have 20,000 miles on them by now: I swap plugs every year, just 'cuz.

[Yoshi823]

I have been playing with spark plugs ever since I read an article in an American mag about indexing by changing the washers. But with a tapered thread, they don't use washers...not that my 750F2 uses that type of plug. The standard plug was the NGK D8ES-L, from what I remember.But as I was going to be using Boyer-Bransden electronic ignition and a set of Andrews Performance coils, I wanted to use a better plug, where cost wasn't an issue. So I went to the NGK D8EV gold-paladium plug. I then read another article that suggested that grinding the earth arm to a point would make a differance, so I tried this on my XL250SA dirtbike with a D8EV installed and didn't feel any change to pickup or fuel consumption. So I bought a box of ten D8EV plugs and marked the side of the plug which aligned with the open side of the plug earth arm, and set about which plug would align the open end so that it pointed towards the centre of the combustion chamber, with a preferance for those that pointed more towards the inlet than the exhaust port. What didn't work in one plug hole worked ok in another hole, so it was down to a bit of experimenting. Eventually I settled on the best set.
I then read another article in a dirt bike magazine from the USA that said to watch out for the internal resistor of a typical OEM plug cap going open circuit and so causing delay of the coil energy getting to the spark plug tip. These resistors should be between 5k-10k ohms...anything higher than this can either be corrosion in the internal parts of the cap, or the resistor starting to break down. I have seen some quite nasty corrosion on the springs inside several caps, so they're worth taking them apart to clean up the bits inside.
On all of my bikes I have now removed the internal resistors and replaced them with a suitable length of brazing rod, after I had an experience which I could have done without. I was coming home from a breakfast run down to the coast, and we wern't hanging around. Halfway across a particularly enjoyable fast stretch of road, the engine falterd and I thought that I was out of petrol...but it was ok if I wound the throttle open wide and revved through the problem area, which was about from 1500 to 3000 rpm. The problem was when coming out of slow corners, when all four cylinders chimed in unexpectantly. Once home I didn't suspect the plug caps, which I had checked over the winter, and didn't see that the internal resistors might give a problem. Once I had tried new spark plugs, the fuel filter, fresh petrol etc I got around to suspecting the plug caps. One had gone open circuit, two were ok, the other cap was on the way, this last one being affected by the heat.

[Don R]

You can buy tapered index washers for tapered plugs or flat washers etc. they are color coded for thickness, usually 3 sizes in a set. There is an indexing plate available when you get a cly. indexed you can screw the plug into the index plate and mark it so new plugs can be indexed to the plate. Easier than on the engine. I use a sharpee to mark the ground strap on the porcelan, You can also mark the socket for ground strap location since it's so hard to see the plug.
 I side gap and index the NGK's in my 567" BBC and run em a full season. I think they are 5672-9's