The seals are Ok, it's the spacer for the flywheel that's the sticking point. At the end of the article the bike shears the flywheel

a bit of digging and this seal "should" do the trick (no guarantees...just did some sleuthing)

https://www.google.co.uk/search?client= ... PfarPlgMgC

Nice ... Close but no cigar
The seal has a locating lip on the outside but I had a few made up

Loving the build, will be something special.
Regarding the flywheel is the sleeve to space the flywheel out from the casing, is it a larger taper needed or different angle of taper.
I ask as couldn't you use a different taper, possibly the gsxr1000 that Mike at gforce used.

Yes the sleeve was to space the T'cat flywheel away from the cases. It has the same taper inside and out with a slot for the woodruff key

Ye thought that was the work around.
Have you run it that way yet, what do you think the chances are of it holding up.
Ive fitted the gsxr1000 wheel to my gsxr4, that's involved altering the taper in the wheel (regrind) and using a katana 400 side case that has had a new end plate machined to hold the Genny that used to fit under the wheel on the main cases.
I feel your pain, the complexity of the work around can be tiring and a small thing can take months.

It's the first engine I've built from scratch and to be honest I'm a bit scared to try it. I think I want somebody to go through it first. I didn't change the the crank shells. They'll probably be Ok but .. well its something to worry about.
I think the flywheel will be Ok the bolt tourqued up Ok and the woodruff key will stop it slipping. There's nothing touching it so theres no drag other than its own inertia. The problem is you have to add about 1mm of material rather than take it away.

That key holds nothing mate, they are purely for position, if it goes it goes.Doh!

Ok .... well fingers crossed then.

this is a great post about the 660 conversion,i can add some of my own findings,the liped crank seal is not necessary,i have used a normal type seal with no problems,i also mounted a trigger wheel to the back of the 3he flywheel to get around stock ignition type pickup,but im also running an after market ignition system with fuel injection,also the fzs 5dm conrods are about 1mm longer than the fzr 3he ones,i had to use the conrod bolts upside down to clear the bottom crankcase,also had to grind a bit out of the 4jh cases on the lefthand side,for crankshaft clearance,im running a low compression motor,with 4tv pistons,3mm copper head gasket,to get around yamahas poor gearbox ,pressed on 2nd gear,i had three pegs made to lock the gear to the shaft,this worked ok but the gear kept breaking so i managed to squeeze a honda cbr 600 f3 gearbox in the yamaha cases,this engine has been dynoed at 316hp with turbo so i can say that yamaha crankshafts are well over enginered for the stock 80ish hp