weird spark plug gap

[cmn1771]

first let me say that my bike runs great but the spark plugs have 16000 miles on them so i thought id change them. the new ones are NGK B8ES. i gapped them to .029 in.

i measured the old ones were NGK BP6ES and they were .038 in. iv never seen a gap so wide in a motorcycle.


i assume these old ones were the originals. just wondering if anyone else has ran across a gap so wide and the bike still run good?

thanks
matt

[Nessism]

The gap on your old plugs spread with combustion cycles and heat. The fact that the plugs fired at such a wide gap is a testament to the quality of the stock ignition parts Suzuki used. For some reason some people like to bash them but I'm not one of them.

[cmn1771]

The gap on your old plugs spread with combustion cycles and heat. The fact that the plugs fired at such a wide gap is a testament to the quality of the stock ignition parts Suzuki used. For some reason some people like to bash them but I'm not one of them.

oh ok. thats logical. thank u

[bwringer]

No idea which bike you have (that's a hint), but who knows where the BP6ES plugs came from -- they're not original.

Sometimes people will screw in any old plug that fits, and sometimes a shop will sell you whatever they have laying around. And sometimes people get bizarre ideas about solving carburetor problems with different spark plugs. Never understood that line of reasoning, but it's sadly common.

And I agree with Nessism -- the stock ignition components are a lot more robust than most people think. Ignitions get the blame for a lot of unrelated stuff.

With all the above said, it's also worth remembering that plugs erode at something more than twice the "normal" rate on a GS. For one, a motorcycle engine spins a lot faster on average than a car engine. But the main cause is the GS "wasted spark" system means each plug fires twice as often as it needs to.

In order to make the ignition system a lot simpler and smaller (you don't need a distributor or the associated gearing), it always fires two plugs at a time, 1-4 and 2-3. So, for example, as plug #1 is starting the combustion cycle, plug #4 is ending its exhaust cycle. The plugs fire at the same time, so #1 goes "bang" as expected while #4 makes a spark that doesn't do anything at all, since any gases in that cylinder have already been burned.

[trippivot]

you got lucky the projected tip didn't crack the piston.


B P 6 es? or B R 6 es? \


.029 is still too wide but they'll run from .015 to .045

[mike_of_bbg]

For some reason some people like to bash them but I'm not one of them.

Not sure who those people are, but the only bad things I see about Suzuki ignitions around here are ignitors going bad. That's certainly understandable after 30 years. Although the Dyna options are great and apparently very reliable at much lower prices than stock parts (where they're still available), we'll have to see how well they're doing in 2041...

[cmn1771]

No idea which bike you have (that's a hint), but who knows where the BP6ES plugs came from -- they're not original.

Sometimes people will screw in any old plug that fits, and sometimes a shop will sell you whatever they have laying around. And sometimes people get bizarre ideas about solving carburetor problems with different spark plugs. Never understood that line of reasoning, but it's sadly common.

And I agree with Nessism -- the stock ignition components are a lot more robust than most people think. Ignitions get the blame for a lot of unrelated stuff.

With all the above said, it's also worth remembering that plugs erode at something more than twice the "normal" rate on a GS. For one, a motorcycle engine spins a lot faster on average than a car engine. But the main cause is the GS "wasted spark" system means each plug fires twice as often as it needs to.

In order to make the ignition system a lot simpler and smaller (you don't need a distributor or the associated gearing), it always fires two plugs at a time, 1-4 and 2-3. So, for example, as plug #1 is starting the combustion cycle, plug #4 is ending its exhaust cycle. The plugs fire at the same time, so #1 goes "bang" as expected while #4 makes a spark that doesn't do anything at all, since any gases in that cylinder have already been burned.

its a 1980 gs550e. manual says gap them .024 - .031 in.

[Joe Nardy]

Does your bike happen to have high output coils? I know the Accel Super Coil instructions specify a larger plug gap, something like .036-.040.

Thanks,
Joe

[cmn1771]

Does your bike happen to have high output coils? I know the Accel Super Coil instructions specify a larger plug gap, something like .036-.040.

Thanks,
Joe

not to my knowledge.

it started fine and idled fine. i was about to go for a ride when it began to rain. si i just put it back in the garage. ill try to do test ride this evening.

[cmn1771]

well, i was able to do that test ride today...

still runs great! i do notice better acceleration in 6th gear.


its so freakin fun to ride

-matt