Zephyr 1100 engine info questions

[Gosling1]

Hi all - looking for some advice from anyone here who has done work to a Zephyr 1100 motor.

What I am specifically seeking advice about - is the bore centres of an 1100 motor, and if they are compatible with MkII 1000 bore centres from the 79-80 models. Also - the diameter of the exhaust port at the header mounting flange surface (i.e. where the exhaust gasket fits).

I am trying to establish if I can use a 4-2 Black Widow exhaust header system - built for a Zeph 1100 motor - on an older Z1000 MkII motor. Even some basic info like the centre-to-centre dimensions of a Zeph 1100 head gasket would be invaluable.

cheers
Dave

[hugojose]

I can tell you this.

The Zephyrs were marketed as 'retro', and although the Zephyr 750/550 engine were the real old workhorses; same engines from KZ/Z/750/550 of late '70s and early '80s. The Zephyr 1100 engine was not related to the early Kawasaki air cooled fours 900/1000/1100.

Those early big air cooled engines were not deemed modern enough for the '90s. Thus the Zeph 1100 bottom came from the liquid cooled 1100 of that time, the ZX11 in the US, and probably the GPZ1100R in Europe. Thus the bottom end is more of an evolution of the liquid cooled GPZ900R of '85. These liquid cooled engines had the camchain on one end, not the center. The top end was back engineered into air cooling using two plugs/cyl and as far as I know shares nothing with the early air cooled engines....this is not to say the exhaust would not fit, but the chances are slim.

The bore and stroke of old air cooled 1100 was 72.5 x 66.0 mm. It was a bored out 900, same stroke.

The bore and stroke of Zeph 1100 is 73.5 x 62.6

.....the question may be answered in the KZR (KZ rider forum in the US), they know a lot about the old bikes and the Zeph 750/550. There is very little info on the Zeph 1100 though, as if considered completely an odd ball.

[hugojose]

...actually, adding to my previous post. was visiting the KZR forum, and coincidentally somebody was asking for
the old Z900-1000 port spacing to see if would fit some old rusty exhaust.

Somebody answered, and I quote;

"On a Z1 head measured with a vernier caliper...
1 - 2 and 3 - 4 = ~94mm.
2 - 3 = ~125mm."

….my guess, and I repeat my guess, would be the old 1100 was probably same.

https://www.kzrider.com/forum/2-engine/ ... rt-spacing

If this helps.

[Gosling1]

thanks Hugo, appreciate your reply. Yes the smaller Zephyr motors (even up to the ZR7 of 01/02) - were basically identical to the 550/750 motors of the early 80's. I know that exhaust systems fit from the Zephyr models to the earlier ones.

I have heard about the bottom-end being based on the ZX1100 motor of the day, but given the massive differences between the 2 motors, I struggle with the entire concept really. The crank may be based on the same design parameters - bearing sizes etc - but the crank-web spacing is completely different to cater for the centre cam-chain.

What would be ideal - is to measure up a Zephyr 1100 head gasket. That will immediately identify the cylinder bore centres. I can't see them being that different to the earlier motors but need to be 100% sure before dropping a couple of hundred pounds (in your money ) on a replacement exhaust system.

cheers

[hugojose]

According to microfiches on the on-line supplier, the gaskets were completely different. The old air cooled 1100 was a two-piece affair, separated at the center. The Zeph 1100 was a single piece. Surprinsigly, the much older engine gasket is still available. The Zeph's is not.

….I only know of one forumer, who rebuilt a 1100 engine. He posted the whole process in the old forum. His name is Scott...going by the name s_in_fl, from when he lived in FL, USA. Now he lives in Texas and as far as I know he still owns the 1100 an occasionally pops in this forum. You may want to drop him a line see if he responds. He may still have the old gasket. (I still have the old 750 gasket from when I changed valve seals)

[750R]

The Crankcase ist not from the ZX1100 but from the watercooled ZG1200Voyager many parts are identical here.
Head an Cylinder-gasket are still avilable as i know - bought two ones in the last year

[hugojose]

Thanks 750R.

Gosling does not want to buy one. He only wants to know the distance between bore centers.