www.zxrworld.co.uk

I finally got round to the stick coil modifcation the other day on my other zxr 400, this is putting the later stick coils back into the zxr 400 instead of using the two coils and the crappy HT leads. This provides a better voltage therfor better spark.

Heres a wee piccy, its pretty large:



It starts on the coldest of mornings with a tiny bit joke. I havent ridden it yet as it has no MOT and i have been doing a bit of work on it to get it all ship shape. But i will let you all know how it feels to ride it and see if it makes a difference to the hot start issue. Will then put this onto my project 400

I'm

mad ive never seen anythin like that before. So they replace the coils totally? and sit right on top of the plugs?
that would be great in getting the coils outa the way from the ramair box.
please, please for more info!

interesting!!! whats that all about then?

thats really smart! where did you get the plug cap coils from?

surely all you do is rewire from the two smaller wires that go into the coils directly to the newer ones?

weird, just had a quick google, and it seems these things have been the norm for bloody years on a fair few bikes...
so do we have to match the voltage etc... or could one just go with say a zx10r setup?

They are coil sticks from a zx6r C2H, i would imagine the B's are similiar. The J model zx6r sticks look too long. With these you only have to trim a part of the rubber off the top to make a good seal (the rubber bits just slide off the coil).

Most coil sticks will do, but the ZX12R ones are too tall (they look it, i havent fitted the airbox with these in yet), not tried zx10r ones (i have a zx10r but havent tried the fit yet). I used a wiring harness from a zx12r and also have another from a zx6r, i bought them a couple of years ago, to do on my project 400.

The coil sticks need to connect to each other Rob on the same coil circuit, so its fairly similiar, the diagram is here:



I am due to convert the project 400 wiring so will make a proper wiring diagram of what connects to what if you buy the wiring harness with them too.

I actually have some of the zx6 ones waiting for my engine. They fit nice. The advantage is not actually the voltage. Its to do with dwell time and heat. If you run them on waste spark, there is little difference. If you run them sequentialy then as the coil only has to fire half as much it has a larger available dwell time up high rpm's. As at high rpm the available window for dwell is less that optimal. It is a great conversion , but to take best advantage it is best to run sequentially. I am working on a sequencer to alloy this on the 400. As for these if you just need to make sure the dwell is not to long at low revs as they will over heat. and that the dwell is long enough up high. this can be checked on the CRO. Mine are mitsubishi units. If they are the same I will test them for you on the ignition test rig and give you the data results. you may wish to direct some air over them to help cool them just incase they are a little high on dwell.........the reason dwell is a problem is that an inductor (coil) is the inverse principle of a capacitor. therefore the current increases exponentially and at ful charge it just keeps flowing untill turned off. hence to long a dwell time will overheat them. if this is the case you can add a series high watt resistor of the correct value. But this increases the required dwell time up high. Anyway enough rambling I will check for you. As those coils are expensive and I would hate to see them burn out. nice mod anyway..

cheers

regards TK400

Thats pretty much what i meant, except i thought you would have connected the coils in parallel to the control wires and not in serial, but it does the same thing

Must say im tempted just for the sake of it.

I remember reading about plug cap coils on the GSXR's years back.

If you conect them in parralel you will halve the resistance of the coils and therefore double the charge current. This will overload the transistors in the CDI. Be carefull of that. Series and parralel resistance rules apply to the coils. Ie serial is addition relationship Rtotal = R1 +R2 where as parralell is 1/Rtotal = 1/R1 + 1/R2 so with R1 and R2 being of equal value Rtotal = 0.5xR hence half the value of one coil. there are other reasons for the serial configuration but this is the primary one.
I only stress this as it is good to understand or else CDI or coils may die...LOL...

cheers

regards TK400

That is a good point actually, not one i considered!

embarrasing actually condiering i now have BEng Honours (electronics) after my name

tk400 wrote:Series and parralel resistance rules apply to the coils. Ie serial is addition relationship Rtotal = R1 +R2 where as parralell is 1/Rtotal = 1/R1 + 1/R2 so with R1 and R2 being of equal value Rtotal = 0.5xR hence half the value of one coil. there are other reasons for the serial configuration but this is the primary one

couldnt agree more!

are you speaking English?

gem

Thats Ok rob...sparkies are pretty thick over here too......lol.....

just kidding mate im mechatronics so I got a hand in all pots.....excuse the pun...lol

cheers

regards TK400

When

tk400 wrote:just kidding mate im mechatronics so I got a hand in all pots.....excuse the pun...lol

thats quite funny actually