1982 XJ650 Maxim Build

You're ready to rock and roll............

 

Got the primer wet sanded and the tank dipped today, need to pick up the gloss top coat and do that tomorrow and it will be done.

IMG_1476 by Justin Schwab, on Flickr

IMG_1475 by Justin Schwab, on Flickr

 

Carbs re-installed into the bike and all the cables hooked back up. I tell you what I think the hardest part of the whole carb removal/cleaning/re-build/re-installation process is getting the damn airbox boots shoved back into the box for removal and back on for install

IMG_1477 by Justin Schwab, on Flickr

Onto the next issue. I bought new plugs for the bike because why not they're cheap, right. So I saw on here and other places that the correct plugs are BP7ES. Well I took the old ones out and they are BPR7ES and the plug tops are different and my plug boots do not plug onto the new plugs. So which ones wrong the plug wires or the plugs?

IMG_1478 by Justin Schwab, on Flickr

 

So I just looked it up and the top part should screw off the spark plug. Never done that one before. Still question remains which plug is right?

 

The genuine plug is BP7ES.
Remove the plug top terminal and install it.

BPR 7 ES is a built-in resistor of 5 kΩ in BP 7 ES for noise reduction. You can use both.
The spark has high voltage and low current, even if there is resistance there is quite little influence on the strength of the spark.

 

the resistor plug may have been used if the plug caps are resistor and po went with non resistive caps



Pick-up coils:
1982-84 XJ650 Maxim: 650 ohms +/- 20% = 520 ohms to 780 ohms acceptable range
Ignition Coils:

Primary side (input from main wiring harness):
2.5 ohms +/- 10% = 2.25 ohms - 2.75 ohms acceptable range

Secondary side (spark plug wires, without their end caps):
11K ohms +/- 20% = 8,800 ohms - 13,200 ohms acceptable range


Spark plug caps:
5K +/- 20% = 4,000 to 6,000 ohms per cap acceptable range

Spark plugs:
0 ohms per plug

 

should be non resistor plug
ohm out your combined spark plug wires and caps if you get 20K go to non resistor plug. if combined you get 11k go with resistor plug



the top does screw off and save them if you need to replace the plug caps you will need them

 

While the resistance won't effect the strength of the spark, the extra resistance will effect the duration of the spark (spark duration is a tuning tool on these machines, in part because of how TCI functions). While the bike will run with incorrect resistance, it won't run quite as well as it should.

 

I measured the discharge waveform of register plug and non register plug with oscilloscope using stock coil, cable, TCI. As a result, I found that using a resistor plug reduces the duration and maximum voltage by about 10%.

But actually I was not able to feel the difference on ride.

I have put a register plug in GPz400F which is specified to use non register plug. At this time, clearly the condition of the engine went bad. I think that if the design of the ignition system of the stock is poor, it may be affected.

I think that it is best to follow it if it specifyied a non-register plug at genuine, but if you mention about XJ, I think that there is no particular problem even if register plug is inserted.

 

I'm not sure that this is true? Increased resistance should lower the peak voltage because it "spreads out" (or "slows down" the RATE of discharge) the available voltage over a longer duration of time, for example (disregard figures used, they are ridiculous and just to make it easy on the math):

non-resistive plug: total energy of 100kV discharged over 5 seconds = 20kV per second average
resistive plug: total energy of 100kV discharged over 10 seconds = 10kV per second average

Are you sure the duration was reduced? I can understand the total voltage reduction.



http://www.ultralightnews.com/enginetroublshooting/resistorcapsandplugs.htm

 

It is interesting data. Certainly in theory I might be wrong.

I looked for the measured data, but I could not find it. I'll measure it again and report the result.

 

Maybe a dumb question but how do you measure the plug wires? The end attached to coil doesn't seem to come off.

 

each coil has 2 spark plug wire measure from end to end .you can leave the plug caps on they unscrew .

 

So I measured the wires from end to end 1-4 and 2-3 on separate coils. I didn't get anything like what you said, I got 31.5K on 1-4 and 10M on 2-3 does this mean my coils are bad?

 

did that include the spark plug caps?
trim back the wires about a 3/8 of an inch on each end and retry

31.5k and 10M is bad coils. and by M you mean megohms ?

 

Yeah that was with the caps on and yes 10M is megaohms

 

the caps unscrew so take them off and remeasure, the resistors in the caps could have failed

so you will be looking for 11k on the coils and 5 k on the caps also test the primary side of the coils

way back when M was equal to K

 

Pulled the caps off and measured to coils directly from the wires.

Both coils secondary measure 11K
Also measured primary on both reads 2.5

Measured the plug caps and 2 and 3 both read 5K

1 cap reads 8.6K and 4 cap reads 11.8K

Put the caps back on 2-3 and measured 21K through everything, maybe corroded connection is why I got bogus before. Still my 1 and 4 caps need to be replaced correct?

Do we know the correct NGK part number for the resistor caps that fit #1 and #4 plugs?

 

yes sounds like wrong caps or resistors are failing our supporting vendor sells the correct after market nkg caps .
he also sells reolacment resistors for the oem caps but you are better off buying the nkg unless you are going for factory restoretion

www.xj4ever.com or this link
XJ4Ever - Supporting Vendor look under electrical

or just start a conversation with member chacal he is xj4ever

to many choices for me to give you a part number