Vibration! A cure for bad vibrations, Spark Plug Caps!!

[FIZZER6]

Re: A cure for bad vibrations, spark plug caps!!

Just like DPaul said, your looking into the high tension lead (HTL) from the coil. There is a spiral wound multi-strand wire in there. I have found that when the screw in the plug cap pushes the core off to one side, engine vibrations increase. I have also found that screw in the cap can break the wires off.

If all is well you twist the caps on the HTL and the wire snugs into the cap AND DOES NOT SPIN FREELY. If it spins freely, trim the wire and fan it out. Screw the cap on. It should screw down and come up snug.

- While the HTL is removed from the cap, measure the caps internal resistance from the screw to the plug lock by sticking probes into each end of the cap. Should be around 10k ohms.

Thanks for the clear up! Just to confirm:
1. HTL = High Tension Lead. This is where the multistranded wire can get bunched off to one side? Does it stay attached the connector end or pull apart without breaking?

2. The "Self Threading Cable Connector" is attached to the High Tension Cable and that connector is actually threaded (screwed) onto the Phenolic Resin Body?

3. To do the "will it turn" test, should I grab the Self Threading Cable Connector and twist it to see if it spins freely? If it does then I would take apart, spread the wires in the high tension cable and reinsert?

I understand why you would want the wires to be spread apart instead of pushed to one side, I'm just not sure how they get like that if you have never messed with them?

This is something I want to do the next time I have a free evening.

 

[dpaul007]

Re: A cure for bad vibrations, spark plug caps!!

Thanks for the clear up! Just to confirm:
1. HTL = High Tension Lead. This is where the multistranded wire can get bunched off to one side? Does it stay attached the connector end or pull apart without breaking?

2. The "Self Threading Cable Connector" is attached to the High Tension Cable and that connector is actually threaded (screwed) onto the Phenolic Resin Body?

3. To do the "will it turn" test, should I grab the Self Threading Cable Connector and twist it to see if it spins freely? If it does then I would take apart, spread the wires in the high tension cable and reinsert?

I understand why you would want the wires to be spread apart instead of pushed to one side, I'm just not sure how they get like that if you have never messed with them?

This is something I want to do the next time I have a free evening.

1. Yes

2. Close, you just have it backwards. The self threading cable connector is attached to the resin body and screws into the HTL

3. You won't be able to actually grab the STCC, you'll need to grab the HTL with one hand, and spin the resin body clockwise on the wire. There is a rubber boot where the two meet that you can push up and out of the way to make it easier to turn. If it spins freely and isn't tight, turn it counter-clockwise to unscrew the PRB from the HTL and perform the steps in the OP.

Trust me, this will all make sense when you actually do it. :thumbup:

 

[lawlberg]

Re: A cure for bad vibrations, spark plug caps!!

So I've read through this a couple of times and can't quite figure out the exact reason why this works - just that it does. I'm guessing it increases the quality of the connection, increasing the quality or consistency of the spark.
My question is - does a bad spark or inconsistent timing of the spark lead to vibrations?

 

[FIZZER6]

Re: A cure for bad vibrations, spark plug caps!!

So I've read through this a couple of times and can't quite figure out the exact reason why this works - just that it does. I'm guessing it increases the quality of the connection, increasing the quality or consistency of the spark.
My question is - does a bad spark or inconsistent timing of the spark lead to vibrations?

Yes, it is absolutely because it increases the quality of the connection. With spark plugs that fire at very high voltages, extra resistance in the path to the spark plug will adversely effect spark timing (by milliseconds) and quality of the arc. It doesn't take much of a resistance increase to cause the voltage pulse to find another way to ground, this is when you get misfires. Even without misfiring the extra resistance can cause the cylinder to fire at a less than optimum time which would increase vibrations, decrease fuel economy and performance by some degree.

 

[TownsendsFJR1300]

Re: A cure for bad vibrations, spark plug caps!!

Just as a side note, Yamaha and most Japenese manuafactures have been using this design (not the exact same cap) literally for decades.

My first 1969 yamaha AT1 125, 1975 RD350, 2 strokes had the same style cap.

The only main difference I see is that the FZ have very short cables (more compact) vs the older bikes and its much easier, (especially when removing) to have the cap loosen from the wire.

 

[FinalImpact]

Re: A cure for bad vibrations, spark plug caps!!

Another factor to keep in mind is we are dealing with TWO plugs per coil in this waste spark system. From the coils output to the plugs tips and everything along the way impacts 2 cylinders!

I've done a fair amount of reading and don't clearly understand how a brass conductor against a copper wire can fail to make a connection voltage wise. So its likely not about the voltage drop or Resistance drop as both the plugs and the caps have built in resistors of about 15,000 ohms which is HUGE compared to the cap & wire contact. From this it must be about capacitance. In this aspect the last coil discharge impacts the next or current coil charge efficiency. This is a transistorized coil ignition so it has 12 volts to one side of the coil always. Charging it and discharging are done by a transistor clamping the coils input to ground to charge it with joules of energy. In that regard its pretty simple. However I think its the "PAIR" of plugs being driven by opposing ends of the coil that makes this connection so sensitive. Remember one HTL has positive polarity and the other negative polarity with respect to what is discharged to the plugs but that doesn't explain why this subtle change makes such an impact performance wise. All I can speculate is that capacitance plays a significant role with respect to waste spark as the energy delivered crosses the DC Zero point. In this realm, DC voltage is blocked by capacitance so it "may" (I'm using this term loosely) impact the coils effective energy during charging. So one cylinder in the pair has the timing of the spark out of whack or the energy lessoned.

In short, less energy OR the wrong time creates harmonics we feel. We feel this not as a complete misfire but as a less powerful stroke. Essentially any given power cycle should accelerate the crankshaft to the same velocity for AFR applied. When it doesn't it creates harmonics that are transmitted throughout the engine and frame.

// all just guessing based on reading.

If you're board, here is some things I've learned about cages.
Modern cars use the crankshaft position sensor to detect misfires. The ECU calculates the expected timeline for the crankshaft to be at its next location and when its NOT accelerated to the proper velocity it stores that data and what cylinder is associated with it. In the states, I believe federal law dictates that a cylinder can not misfire consecutively for 200 times without setting a P030# (# is cylinder no.) cylinder misfire error as this translates to unburned hydrocarbons. This is based upon literature from Ford, Toyota, and Mazda who speak to consecutive misfires and the magic number is always 200 misfires.

However, Toyota unlike Ford and Mazda, have an amplifier outside of the ECM which fires the coils. The perk here is this amplifier module also looks at the ring back signature of ignition coil collapsing (the electronic spike produced by a magnetic field collapsing; its what spark from a coil does). In short, if the signature doesn't match what is expected it can tell a specific plug did not fire. Toyota also measures crankshaft velocity to determine misfires. But they get the added benefit of knowing if the spark plug had energy delivered to it. Thus some of the Toyota system can tell if it was Fuel issue (injector) or spark issue that contributed to the misfire.

 

[TownsendsFJR1300]

Re: A cure for bad vibrations, spark plug caps!!

deleted post..

 

[lawlberg]

Re: A cure for bad vibrations, spark plug caps!!

Just did this today - and changed the plugs -

I had a little corrosion on #1 - similar to what was shown in a previous picture here.

Rode the bike - so much less vibration it's great - though still some. I'll need to do a TB sync sooner or later, but finishing up the seat cowl and doing my plugs was a good day!

 

[FinalImpact]

Re: A cure for bad vibrations, spark plug caps!!

Just did this today - and changed the plugs -

I had a little corrosion on #1 - similar to what was shown in a previous picture here.

Rode the bike - so much less vibration it's great - though still some. I'll need to do a TB sync sooner or later, but finishing up the seat cowl and doing my plugs was a good day!

Q? Were any of the cap to wire connections loose?

If they were CR9EK plugs, was the gap worn over spec? Just curious which item contributed to it running smoother. Tks!

 

[lawlberg]

Re: A cure for bad vibrations, spark plug caps!!

I trimmed and re snugged the caps - they weren't super loose - but they definitely weren't tight.

I didn't gap them - after, but they all looked about right, nothing super filthy or gummed up either.

 

[DavesFZ]

Re: A cure for bad vibrations, spark plug caps!!

Edit: nevermind, missed the last few posts with more info.

 

[DavesFZ]

Re: A cure for bad vibrations, spark plug caps!!

I'll need to do a TB sync sooner or later

If you are ever venture over towards Toledo, I live about 30 miles north in Michigan and have a carbtune sync tool you are welcome to use.

 

[DavesFZ]

Re: A cure for bad vibrations, spark plug caps!!

Wow, just put in 4 ngk iridiums and shortened the cap wires and it is much smoother with the vibes. Strangely the Leo Vince exhaust sounds quieter and smoother to my ear as well. All 4 caps were spinning freely but I've only got 5000 miles on it. Thanks for giving me the courage to do this!

Eta: I am a novice and this took me 1.5 hours start to finish from the side of the bike. I dropped the radiator a few inches to make the necessary room. :thumbup:

 

[lawlberg]

Re: A cure for bad vibrations, spark plug caps!!

If you are ever venture over towards Toledo, I live about 30 miles north in Michigan and have a carbtune sync tool you are welcome to use.

Thanks a lot man! My roommate is from Temperance (I'm guessing a few miles south of you) so there's a good chance we'll wander out that way before the season is over!

 

[rankinx]

Re: A cure for bad vibrations, spark plug caps!!

Just did it on mine this morning, and, what a difference!

Cable 2 3 4 was loose. I had to cut a bit of cable on the 2nd one because it wouldn't be tight.

I thought the vibration over 6k was normal, it's been doing it ever since i got the bike. ( bought it used last spring )

I fixed whatever problem i didn't know the bike had, runs smoother now.
I looked probably like a total dickhead this morning while trying out the bike in the street revving the bike like a maniac though hahaha.

Thanks for the tip, i should have done it when i replaced my spark plugs 2 months ago.

 

[FinalImpact]

Re: A cure for bad vibrations, spark plug caps!!

Just did it on mine this morning, and, what a difference!

Cable 2 3 4 was loose. I had to cut a bit of cable on the 2nd one because it wouldn't be tight.

I thought the vibration over 6k was normal, it's been doing it ever since i got the bike. ( bought it used last spring )

I fixed whatever problem i didn't know the bike had, runs smoother now.
I looked probably like a total dickhead this morning while trying out the bike in the street revving the bike like a maniac though hahaha.

Thanks for the tip, i should have done it when i replaced my spark plugs 2 months ago.

This is very interesting when no other changes are made; i.e. replacing the plugs. Thanks for posting!

 

[DavesFZ]

Re: A cure for bad vibrations, spark plug caps!!

I, too, bought mine used. Mine only had a few thousand miles on it and I thought the fz6 just rattled like a beast above 6000 rpm normally. Now that I changed this and lessened those vibes, I like the bike much more. I bet the previous owner wouldn't have sold it to me if he did this himself, because he mentioned the vibes sucking. Seat vibes are totally gone now, bars are significantly less, but still have high frequency vibes in the foot pegs.

 

[dpaul007]

Re: A cure for bad vibrations, spark plug caps!!

Very cool to see this working for a lot of people! Rode the bike in to work today. First time since doing this and it felt pretty smooth; also noticed a reduced noise/drone from my LV pipes, same as DavesFZ.

Once again, thanks FinalImpact! I'm going to go ahead and throw my vote in to sticky this thread!

 

[FinalImpact]

Re: A cure for bad vibrations, spark plug caps!!

Very cool to see this working for a lot of people! Rode the bike in to work today. First time since doing this and it felt pretty smooth; also noticed a reduced noise/drone from my LV pipes, same as DavesFZ.

Once again, thanks FinalImpact! I'm going to go ahead and throw my vote in to sticky this thread!

I revised the OP and hopefully clarified a few things making it easier to understand. And by request, Its' now Stuck! :thumbup:

Thanks everyone!

 

[ozgurakman]

Re: A cure for bad vibrations, spark plug caps!!

Hi! my bike's #2 and #3 spark plug caps' resistors are 9k on ohm-meter... I measured againg and again, nothing changed... their resistance is 9k ohms altough #1 and #4 are at ~10k ohm.
Could I need to change that caps? (sorry about bad English)