spark plugs

[Guest redguzziv10]

I recently experienced an intermittent misfire while driving in the high revs.

On inspection of the plugs i noticed one is starting to "blister" on the ceramics, just below the spark gap.

Can anyone tell me what is causing this ie. will it happen again after i change the plugs.

are these NGK iridium plugs worth paying the extra for as well?

I know i am advertising my ignorance on all things techy here, but advice would be gratefully received.

BTW. the bike has only done 6000 miles and is basically stock, except for G Force cans.

[jrt]

Sounds like you are running lean- a very common problem. You can compare your plugs to those on this page but give them a little latitude for individual variation. The fix is to richen the mixture- are you comfortable resetting the TPS? Also check your valve clearance and make sure it isn't set to 'American' specs.

Iridium plugs are a waste of money, in my opinion. With a low tech engine like we have....use a plain ol' single electrode spark plug.

It's a good thing to ask questions. I didn't one time and I fried the electrical system on a Subaru. We all have a lot to learn.

[Guest redguzziv10]

Thanks for that JRT.

it looks as though i may be running a bit lean, according to the chart. I'm off to our national Vee Twin rally this weekend, so maybe i can ply someone with drinks to show me how to adjust it correctly.

i can probably do it myself in my unique caque handed way... but i want to keep the bike running for a few more years yet

[Guest ratchethack]

I recently experienced an intermittent misfire while driving in the high revs.

On inspection of the plugs i noticed one is starting to "blister" on the ceramics, just below the spark gap.

Can anyone tell me what is causing this ie. will it happen again after i change the plugs.

are these NGK iridium plugs worth paying the extra for as well?

I know i am advertising my ignorance on all things techy here, but advice would be gratefully received.

BTW. the bike has only done 6000 miles and is basically stock, except for G Force cans.

58560[/snapback]

What Jason said. Do a search on iridium for the discussion. Generally speaking, an intermittent misfire isn't attributable to plugs unless the plugs are either badly burned or badly fouled. I don't know about "blisters" on the ceramic "tower", never heard of this before, sounds like a fluke. Unless you're also getting signs of being in the wrong heat range (see Jason's link) I wouldn't worry about your plugs. Keep in mind that a little carbon fouling on V11's is normal, particularly on the right-side plug on the "shadow side" of the flame-front travel.

 

Many have posted on a pesky, very occasional stray "misfire" that for the most part doesn't seem to occur in power-on conditions. I've got this but have tuned it nearly all the way out by setting the valves to .006" and .008" and keeping the TPS in the right range as Jason suggested. Some have speculated that the errant pulse drop is due to a firmware fault in the ECU. The strange thing is that it only seems to drop one pulse, then it's OK. If your idle is set too low, and/or if your TPS isn't set properly, it can be enough to cause the engine to conk-out. I've just learned to live with it.

[Guest redguzziv10]

Don't you just love 'em

And i thought changing from my Mk4 Le Mans would mean less spanner time.

[jrt]

look at the 'spark plugs' thread (Nogbad was last to post on it) in this Tech Topics. I didn't remember it, but someone posted a picture of there (just fine) plugs. Just fyi.

Regarding the TPS- it is easy to adjust, but it is also nice to have someone around to point at stuff and help drink your beer. You can do twice as much damage in half the time that way.

[Guest aironepony]

Sounds like you are running lean- a very common problem.  You can compare your plugs to those on this page but give them a little latitude for individual variation.  The fix is to richen the mixture- are you comfortable resetting the TPS?  Also check your valve clearance and make sure it isn't set to 'American' specs.

Iridium plugs are a waste of money, in my opinion.  With a low tech engine like we have....use a plain ol' single electrode spark plug. 

It's  a good thing to ask questions.  I didn't one time and I fried the electrical system on a Subaru. We all have a lot to learn.

58563[/snapback]

 

An excellent plug guide; many thanks. My left plug looks like "13" and the right plug like "20"

 

Is Ok innit?..............

[jrt]

I dunno. I just accidentally ran across that page. They sound good to me, and if you're happy with them......

[belfastguzzi]

It's  a good thing to ask questions.  I didn't one time and I fried the electrical system on a Subaru.We all have a lot to learn.

58563[/snapback]

Yep. You only needed to ask and she would have told you that she'd prefer bacon and egg, maybe even a mushroom.

[dlaing]

An excellent plug guide; many thanks. My left plug looks like "13" and the right plug like "20"   

 

Is Ok innit?..............

58614[/snapback]

On our air cooled twins, the two plugs should be close to identical, categorically.

I think your situation indicates that the right is running too hot.

Probably because of air bypass screw or throttle body imbalance.

Check it out before you burn your right exhaust valve or cause faster wear on the right side.

I may be paranoid, and the difference is acceptible, but I doubt it and I would check it out soon.

[Guest Nogbad]

On our air cooled twins, the two plugs should be close to identical, categorically.

I think your situation indicates that the right is running too hot.

Probably because of air bypass screw or throttle body imbalance.

Check it out before you burn your right exhaust valve or cause faster wear on the right side.

I may be paranoid, and the difference is acceptible, but I doubt it and I would check it out soon.

58645[/snapback]

 

I agree with that. I doubt it's the bypass screw as this passes very little extra air under normal loads. Most likely its unbalanced throttle bodies as DL says. Check soon as that plug looks overheated. Look carefully at the plug again. If you can see little blue/black glassy specks on the ceramic centre, that cylinder is running much too hot and you are in danger of valve damage.