Flywheel / Alternator Tech

[Kato]

Because I've been asked about this a few times recently I thought I'd have a go at writing a bit of guide, there is often talk on this board of engine swaps, mostly people looking to transplant a 900 motor into their 600's, this is not usually a problem if you can find a 900 motor of the correct variety, the 1 question I get asked most often is
"can I use an injection engine with carbs"
The answer is YES, you just need to swap a few parts around, it’s not all that tricky to do, there are a couple of gotcha’s but also advantages the later motors use the 3 phase alternator, much better than the old single phase ones that keep cracking, a little wiring mod will be needed later but it’s not hard to do

1. Flywheel
2. PickUps
3. Case Oil seal for the wires

And thats pretty much it, the first task is to remove the clutch slave cylinder then take off the side case to reveal the flywheel assembly.

Remove the nut from the crankshaft and the flywheel will pull straight off, taking note of the alignment marked by the dot on the flywheel,

Now remove all the allen bolts to separate the alternator case from the flywheel, then flip it over to remove the sprag gear, this can be done by putting back a couple of the allen bolts just loosely on the wrong side and gently tapping them through the sprag will eventually come out, be patient it’s a tight fit.

I’m putting this one back together with a light alloy flywheel from CA Cycleworks, you don’t have to use one of these but it might be cheaper and easier then sourcing the correct part from the dealer, of course the advantage is your engine is going to pick up revs a bit quicker, or you can just swap the parts straight from the smaller engine.

Looking at the two flywheels there isn’t that much difference, I apologise for the crap photo, note the trigger on the alloy one, the main difference here is that the steel one on the left is just over 1lb or for those of you that speak French 534 gms heavier than the alloy one, a not so insignificant saving in rotating mass and in my opinion well worth the effort, when putting the assembly back together there is a little dowel that lines everything up, I only mention this because the last time I asked the question “is that a spare one” pointing to said dowel on the bench the was an eruption of expletives followed by much dismantling, more swearing and a lot of low flying spanners, use the dowel to get the sprag lined up and then with 2 or 3 of the allen bolt evenly pull the sprag into the flywheel, you'll need to take the bolts out after to put the alternator caseing on


So the flywheel assembly is back together and looking like these

It’s time for the most important part of the job............


The two assemblies in the picture are essentially the same, the only difference being the one on the left is fitted with a Corse lightweight alternator, to feed my fetish for all parts not really necessary for a road bike and probably not a good idea if you ride in the dark as they do not push out the power of the standard one, your lights won’t like it, that aside they are fairly easy to source S/H the problem is they never come with this bit and will never fit without it and of course you cannot buy that part seperately from Ducati