Wasted spark

[speed_triple_gav]

Can anyone tell me if the 3 cylinder T3's run a 'wasted spark' ignition system like most 4 cylinders (ie. there's a spark every turn of the crank).

As there is only 1 TDC mark for each cylinder on the crank, surely this is the case?

The reason I'm asking is I'm now paranoid that I've put the cams back in with the engine out of sync.

Really don't want to take it apart. Again

Cheers,

Gav

[deanzywicki]

Gav,
I was wondering the same thing. When I thought everything back together, but in reality the cam chain was off the crank sprocket. I was pretty sure that I had only turned the crank a little bit and rolled it back to TDC on 1. I had this nagging thought that Maybe I had turned it past 1 revolution as I was wondering why the cams weren't moving. Then I started thinking, how do you know when it's at TDC for the intake or exhaust stroke? Curious minds are dying to know.

Dean

[roadrunsl]

I don't know about the sparks, but there is only one way to put correctly crankshaft and camshafts together, as it says in the manual:
T1 mark on crankshaft has to line up with the center of the pick up coil and the two arrows on the camshafts sprockets pointing towards each other and level with the gasket surface.

[daytona 750]

it doesnt matter if the crank is 360* out or not, as it is the position of the cam shaft that dictates what stroke the cylinder is on, all you need to do is ensure that cylinder 1 is at tdc, and that the arrows point to each other, and your engine is setup right.
i hope that makes sense, it does to me, but its sometimes difficult to explain these things when in reality it is a very simple idea, that comes across as a not so simple one.

[speed_triple_gav]

I know for every 2 turns of the crank there is a full engine cycle. Therefore the pistons reach TDC twice (obviously on combustion and then exhaust)...

I'm told on cars with distibuters the spark is every other rotation of the crank and usually on 4 cylinder bikes with shared coils the bike sparks on every rotation with a useless spark on the exhaust stroke.

My question really is how does the pick up know which one is which?
If it fires every turn then no problems obviously but if it fires every other rotation you don't want it firing on the wrong TDC.

I may just be being very thick here (it's quite a common occurence).

[daytona 750]

i guess it MUST fire every rotation, as there is no sensor on the cams, so it would not know which stroke it is on

[ozjimmy]

With a car the dizzy is driven from the crank at 2 to 1 ratio. On a bike the rotor is directly on the end of the crank, so yes it fires every rotation. It's not a wasted spark, just a pre spark check.

[speed_triple_gav]

Thanks chaps. That's reassured me.

I need to rest my brain now.

[Lushy]

As you probably know Gill instrument had a hand in the ignition system for the triumphs. Here is thier idea of wasted spark.

http://www.gill.co.uk/products/digit...wast_spark.asp