SV650 Scitsu Application

Does anyone use a Scitsu tacho on their minitwin, I am trying to confirm if the SV (carb model) runs a wasted spark system?

Thanks for any advice

AJ

[flymo]

cant be a wasted spark as it has two ignition coils, one for each cylinder.

I had a FZR400 race bike that did have wasted spark, two ignition coils for 4 cylinders.

So, you need a Scitsu suited to a single cylinder (only pick up from one lead) with no wasted spark.

I think thats the 'White' version tacho.

I don’t know, I think it IS a wasted spark system … I think it has two coils as it would be impractical to have one, not coz they fire at different times …

At the end of the day, there is only one pickup and it is on the flywheel (so gets triggered once per rev), not the cam (1/2 speed of crank, so 4-stroke)!!

Unless the CDI does something clever I can’t see that it is NOT a wasted spark system. But unfortunately adjblade, I too am only making an educated guess and can’t categorically confirm or deny … soory

[flymo]

Originally Posted by Blue_SV650S

I don’t know, I think it IS a wasted spark system … I think it has two coils as it would be impractical to have one, not coz they fire at different times …

At the end of the day, there is only one pickup and it is on the flywheel (so gets triggered once per rev), not the cam (1/2 speed of crank, so 4-stroke)!!

Unless the CDI does something clever I can’t see that it is NOT a wasted spark system. But unfortunately adjblade, I too am only making an educated guess and can’t categorically confirm or deny … soory

But blue there would be no point in having two coils. The idea of wasted spark is that multiple cylinders can share a coil. On my Yam each coil had two cylinders each so that meant that one of the pair would fire a spark on the exhaust stroke, wasting it.

Some twins only have a single coil that fires both plugs at the same time, again one on the exhaust stroke for one cylinder.

On the SV I cant see any reason why there would be two coils other than to dedicate one coil to its own cylinder.

[flymo]

AdjBlade, as you know though these tacho's are expensive so probably best to call the man from Del Monte and get it from the horses mouth.

Out of interest, are you adding one for any particular reason? or just a fashion statement ........come on be honest.

Er, I understand the concept of wasted spark … and it is there for simplicity of the electronics

As there is only one pickup and it is on the crank, you are either going to have to alternate the firing between each cylinder/coil every rev, or to fire both every time and just 'waste' it … I don’t care if it is physically 2 coils, it has to be easier to simply waste it

Agreed as it has 2 coils and an CDI/ECU, it could be single spark, but I am not sure having 2 coils is conclusive enough evidence to determine that.

Anyway, look in the blurb at the front of the ignition chapter in the manual, it might say as a comment in there if it is wasted spark …

Oh and thinking about it, it HAS to be a wasted spark system

Else how would you be able to set the cams up when rebuilding an engine .. think about it!

[flymo]

Originally Posted by Blue_SV650S

Oh and thinking about it, it HAS to be a wasted spark system

Else how would you be able to set the cams up when rebuilding an engine .. think about it!

I'm with you dude....... Having had 10 minutes to let this sink in. I think the only benefit to having a wasted spark but still retaining two coils is to keep things simple, the ignition timing can run at engine speed rather than half engine speed.

[flymo]

Originally Posted by Blue_SV650S

Er, I understand the concept of wasted spark … and it is there for simplicity of the electronics

Sorry, wasnt trying to teach you to suck eggs , was thinking (typing) out loud

I have one of these on my bike, If you phone them up they will be able to tell you what tacho you need. The pick up lead runs off a single coil to get the correct reading so it will be a wasted spark design, it does also have 2 coils though. I'll go get the instructions and box tomorrow from the garage and tell you which one it is if you like.