A/C 71- 73 Center seal ?

[wankel303]

They left an un-machined area or chunk off of one end to use in the chuck that became waste.  The stepped version doesn't create any waste.

The manufacturers of these seals do a fantastic job of machining on them.  I am always impressed at the fit they get when it's all together. 

The only debate I have had regarding the stepped version is that it creates more crank volume in one cylinder than the other. Some claim that itty, bitty little bit makes a difference while others deny that has any effect on the performance of the engine.

 I have not seen any difference in performance between stepped and non-stepped center seals personally.

[Cheetah73]

They left an un-machined area or chunk off of one end to use in the chuck that became waste.  The stepped version doesn't create any waste.

The manufacturers of these seals do a fantastic job of machining on them.  I am always impressed at the fit they get when it's all together. 

The only debate I have had regarding the stepped version is that it creates more crank volume in one cylinder than the other. Some claim that itty, bitty little bit makes a difference while others deny that has any effect on the performance of the engine.

 I have not seen any difference in performance between stepped and non-stepped center seals personally.

The only thing that doesn't seem to make sense is why don't they try to bring the tolerances around the center and the crank itself a bit closer. It seems they could make them a little smaller in the I.D. but alot of folks say the fluid lock still takes place just as well. In 74, cat made a one-piece disk permanent and it has a much tighter clearance between the I.D. and the crank itself. Which way is better? Just speculating...

[wankel303]

The 74 T1D is a different bird than the previous T1s.  It's interesting to see the improvements/evolution when you put a T1D next to a T1A.  Some are little things, like the supposed improved chrome alloy used on the cylinders ( I say "supposed" only because I have T1D with peeled chrome at home), different exhaust manifolds, and different cylinder head squish, while others like the CDI ignition and the center seal are more blatant.  Even little improvements like the different Nippon Denso external coils used by the 73 T1s make ya wonder how many issues these early Kawis had out of the box. 

It'd be nearly impossible to tell if the clearance between the ID of the center seal and the OD of the crank has any impact on performance at all.  Tell ya what though, the T1As sure do seem to have more snort than the later T1s!  Maybe it's more size and weight of the sleds the motors are sitting in, maybe a more free-flowing exhaust, maybe the Tilly instead of the Walbro, and maybe it IS indeed the motors and/or clutching.  Who knows!? Even so, the T1s were laid to rest when T7 appeared on the scene.

[Cheetah73]

And in the end, maybe kawasaki got tired of all the issues cat was trying to make them improve on and/or cat got tired of engines that didn't hold up. I suppose Cat got together with the kawi R&D over the years and said, we are having issues with this and that, and we need you guys to improve these. Must have happened many times over and in the end I guess the relationship must have went sour and arctic decided to switch over to suzuki for 76. Or was it kawi that dumped Cat as a buyer?
Then kawi started making their own sleds after aquiring sno-jet and also picked up john deere as a buyer.
I don't know the real facts but merely speculating on what I have seen happen over the years. Makes for some interesting reading