Mystery framed project racer

[a4beanie]

Purchased this frame, engine and boxes of bits 2 yrs ago but only just started to piece it together to see what I actually have!
It came with a 1975 z1b engine, bottom end completely rebuilt with a standard crank,as original crank had alternator end cut off.
Barrels are bored to 73mm, I have the old pistons but no rings.
I think it has come from the states as frame stamped SPB #### KZ1.
The Wheels are just a set i had from my old ktm supermoto just to roll bike about but it came with some period 18in CMA alloy rims.
The biggest headache will be sourcing a tank,looks like something along the lines of a moriwaki or xr69 tank will be close.
Looks like I will be having many hours of fun building this through the coming months/years!
[image][/image]

[chrisNI]

That’s got potential…

[Philippe]

Hi a4beanie

that looks like an endurance racer. It seems to be a very special project, good luck with it!
Keep us informed please.
GrtZ
Philippe

[Z1streetfighter71]

You might get lucky with a Zr1100 tank, looks like the same shape frame, if you know anyone with a zephyr 1100 to throw you dimensions?

[moizeau]

That frame looks a lot wider than the Zeph11. If I get chance later I'll whip the tank off and have a measure.

[Ultim8pc]

Very nice project you have there. Be interested to see what you do with it.

[Mathh]

Great looking frame and great looking bike , even with those wheels. I love endurance racers because of the very interesting technical solutions which are always very visible. Over the last 8 years (!) I have been building one myself from scratch, although not a Kawasaki. Mostly Oldskool but with some modern parts.

[Andy M]

Any idea what the frame is ??

[weaver]

Sparton?

[Big Fluff]

73mm bores on standard block is max and are prone to excessive oil consumption.
Nice project for sure.

[a4beanie]

Thanks for the comments, i have searched for frame builders to see if I can find anything similar and my conclusion is the frame is a custom one off closely following the lines of a moriwaki/spondon big tube, I was told that back in the good old days frame builders would make foreign orders on weekends or after hours for racers to their specifications,it could be one of these but having numbers stamped on headstock just confuses me.
Heres an image of a moriwaki z1 frame that closely follows my frames lines.

[Z1streetfighter71]

Looks fairly close and a Gpz1100 rear end on it too by the looks of things and that 75 engine looks like it has a MK2 alternator cover, have you peeked inside yet?

[a4beanie]

Looks fairly close and a Gpz1100 rear end on it too by the looks of things and that 75 engine looks like it has a MK2 alternator cover, have you peeked inside yet?

I have checked the state of tune of the engine, it seems the bottom end has been fully rebuilt by previous owner for road use, I have the race crank boxed for future builds!!
Cylinder head looks to have had port work done and has been rebuilt and ready to bolt on once a suitable piston kit is sourced, the 1015cc barrels are on maximum oversize at 73mm so I have the option of finding rings for the unknown pistons or getting it resleeved to 1075cc.
Cams are unknown but someone may recognise the markings but I do have a new set of APE K410 to use.
The original cam cover looks to have oil feeds to give extra oil to cam journals,but again standard cover included.

[zed1015]

Cams are D grind Kenny Harmon ..
With the pistons being cast and with the two rows of oil holes they may be from a Hodna.
I had an ex race motor with almost identical pistons and they were two sets of OEM ART CB500T pistons which was a common mod before aftermarket performance pistons were readily available.

[chrisu]

73mm bores on standard block is max and are prone to excessive oil consumption.
Nice project for sure.

Not necessarily true. My 1105 Z1 does not use oil.