Hey, I go thru about 6 spark plugs a month. i'm using the NGK B9ES mostly. I've tried the BR9ES but the same problem occurs so here it is; I'll be driving down the motorway just fine, speed will be good including good accel. The bike will come home and sit in the garage till the next day. Starting up will be one or two kicks but usually one. Driving, driving then power will start to bleed away until eventually one cylinder gets me home. A change of plugs and the situation is fixed only to re-occur again later.

The plugs seem to get damaged internally since they wont react to a spark generator after removal. Heat and mixture seems to be ok when reading the plugs on both cyl right after a good run.

I'm suspecting bad coils, internally broken HT leads or faulty HT caps. Any ideas on a solution?

Don't know but I had problems with the TPS once so that might be worth a check. Not sure how it would affect the plugs though. I'm using plugs I got from Matt not sure what they are but no problems with them. If I can find the box I'll let you know.
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If the rats eat my wiring one more time....

The plugs will also die if your a bit rich on the main jets.
On my 18 I went up on the mains jet sizes after doing the airbox mod.It was stock (128's) so I went up to 135's but it killed the top plug within about a mile of riding.I went down to 132's and it still did the same but I was able to ride it for a lot longer before it died again.I went back to the stock sizes and have never had anymore problems.
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Harley Davidson is the worlds most efficient way to turn petrol into noise without the harmful side effect of horsepower.

Generally, the only thing that stops plugs firing is a short between the centre and outer electrodes. The internals are a pretty solid unit, so I suspect as Wayne says, there's something going on with the mixture.

Have you tried cleaning the plugs with something like brake cleaner and using them again?

Not sure what could be wrong on the ignition side to knacker them, they've been desinged to run at thousands of volts and the NSR is unlikely to be producing more without having serious consequences with other parts (ie if it was putting out 20 volts, then I suspect the coils would produce more output, but the rest of the electrics would fry...)
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

Thanks guys, I'll try looking at the mix. As you know The MC18 comes with the TA20 carb. When I bought this bike and tore it apart, I found the carbs to be a set of TA21 B's. I suspect that these flow a lower volume of air since the MJ and SJ sizes were both as specified for the MC18; 130, 132, 35. Anyway, the previous owner seemed to have the settings too rich since he removed the airbox, oilpump and left the oil feed nipples at the rear of the carbs open! It did'nt solve his problem though.

I filled the MJ's with lead and etched (via electrical means) the jets to be exactly 125. It solved the top-end richness but the bike is still very heavy on fuel if you putter around. the plugs DO get all coked-up after a slow-slow ride. I can't however use the same method for the SJ's to get them smaller since the wholde thing has an emulsion tube attached to them. Any help?

Alwyn wrote:
I filled the MJ's with lead and etched (via electrical means) the jets to be exactly 125. It solved the top-end richness but the bike is still very heavy on fuel if you putter around. the plugs DO get all coked-up after a slow-slow ride. I can't however use the same method for the SJ's to get them smaller since the wholde thing has an emulsion tube attached to them. Any help?

Er... buy some smaller slow jets?!

What size are they now?
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Andy.
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Alwyn wrote:

It solved the top-end richness but the bike is still very heavy on fuel if you putter around.

18's do like a drink .An 18 with the same mods as a 21 will use 2 tanks of petrol for every 1 tank of petrol that a 21 uses .
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Harley Davidson is the worlds most efficient way to turn petrol into noise without the harmful side effect of horsepower.

Yeah, that does ring true. Steve's MC18R5K would really go through the stuff compared to my 21 on a run, whether it was steady going or hard riding.
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Andy.
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I have asked my local bike guy for smaller SJ's but he's trying to pedal them to me at the eqvalent of $80 a piece. Nowhere else I look seem to be able to help me out and I'm definatly NOT going to spend $160 on something that MIGHT fix my problem,

Andy, is there any trouble with using a B9ES / BR9ES as opposed to the BR9ECM plugs?

Alwyn wrote:
I have asked my local bike guy for smaller SJ's but he's trying to pedal them to me at the eqvalent of $80 a piece. Nowhere else I look seem to be able to help me out and I'm definatly NOT going to spend $160 on something that MIGHT fix my problem,

Andy, is there any trouble with using a B9ES / BR9ES as opposed to the BR9ECM plugs?

Best thing you can do is use another supplier! Slow jets aren't difficult to get hold of, and not that expensive.

As for plugs; I don't know about the B9ES and BR9ES. I wouldn't use them as they are not specified by Honda, and it's hard to diagnose a problem when you aren't using the correct parts... the plug failing may just lay in the type being used!

The overall issue sounds like the symptoms described in another recent post that turned out to be an electrical fault concerning the pick-up coils.
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Andy.
NSR-WORLD.COM

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