Z750 Twin Forum

Michael - the frame will be seriously modified ! But here we are in my field of expertise [ see my Porsche 550A Spyder replica chassis ] - space frames / structures. If you look at the Norton - the main frame diamond [ top ] will be very similar. Imagine that joined on to the lower OEM KZ750 engine cradle. At the moment my plan is to use a set of BSA Bantam forks [ !! ] modified to look like old girder forks and also with additional strengthening / springs etc.

I will draw a rough proof of concept [POC] sketch in the next few weeks before actual work begins.

Do any of my German cousins know about the Boardtrack event at Bielefeld ?

Hi TJ,

that is really the next project !

I was thinking about a Board Tracker as well, but only for a short period of time
Using a slim 19"-rim in the rear, same tire size as the front tire.
For the old style look a drum brake in the front would be needed.
Mounting a standard tubular steering bar, but to turn it upside down for a low hand position.

Well, I didn't even started this project, too many others are waiting

Good luck,
Michael

BTW: I don't know the event in Bielefeld, but we have some members more or less close to it.
Maybe they know anything about that event.

The 550 chassis picture didn't load previously

Wheels are XLR 125 Honda Trailee. 21" front and 18" rear. I have the option to have a 19" / 21" rear rim laced - but the rear rim is alloy and the whole thing excellent condition. I have found a tall profile 18" tyre that will work. If it doesn't look right, then I'll have to get a new 19" / 21" rim laced on.

YES - drum brakes for the look ..... but I doubt if 125cc Honda drum brakes will stop the KZ with 40DCOE Weber ! SO - drum brakes for looks - and either a trans [ gearbox sprocket ] disc or caliper operating on the rear sprocket .... for self preservation !   

The bars from one of my old BMW Kays doesn't look too bad turned upside down.

The Glemseck fuel cell will work OK in the triangular shape behind the engine. I'll get patterns made over the weekend.

Cafe Creme - the Boardtracker - The parts start arriving ! The Honda XLR 125 wheels and the new front tyre arrived this week. The rear tyre should be here on Monday

POC time .......... yes - the Bantam forks will work with the XLR front wheel. The wheel spindle slot just needs opening up a tad to take the Honda spindle [ which just needs shortening ] and tyre clearance is OK. 

I think the fork legs need to be a couple of inches shorter [ cosmetics ] - AND I wanted to get that Motobecane "banana" fork look. Again, what worked in my head looks like a goer. Unfortunately I ran out of sufficient garden hose [ !! ] to mock up the complete banana shape - but at least you can see where I'm going with it ..... bit of imagineering required. 

Who needs cad-cam !

I'm going to use a couple of seat springs [ see pix ] at the top to give the illusion of suspension, and to a degree they will add some additional springing. ALL parts are available to refurb the Bantam forks - and not expensive.

Hi TJ,

nice idea !

With the expected "strength" of that fork I wouldn't fit any more brake power to the front wheel than the drumbrake of that little Honda
Probably you have to support it with your shoe soles (and a good rear brake, of course).

Some examples of Springer forks can be found here:
https://www.wwag.com/cgi-bin/WebObjects ... e=%2151491

In your mock-up, isn't the "bananatube" on the wrong side of the fork ?
I expect to have the "bananatube" and the extra springs in front / at the frontside of the fork.

The upper part of the triple tree needs extra guides / bushings, to support a parallel motion and to keep the springs in place.

Just my thoughts

Cheers, Michael

Thanx for the link Michael - very useful ! And of course I appreciate your continued feedback.

Ref; the "Banana" fork ..... I have the idea in my mind for the Motobecane style - very elegant.

One of the reasons for the additional "girder" tubing is of course to strengthen the Bantam forks - I doubt if they would support the weight of the KZ lump - forget the braking !

I intend to run a small disc on the gearbox sprocket [ trans brake ] or if that is not possible - on the rear sprocket with a small Willwood caliper hidden in the tubing. I KNOW rear wheel braking is nicht gut, but this will not be a long distance tourer ! 

I would also like to incorporate a hand gear change - again just for the period look. I will probably link that up with a normal foot change to be practical.

Yes, at the top end of the additional fork leg there will be a sliding pillar inside the barrel springs to locate the vertical movement and also to provide the top fixing.

MUCH simpler would be a 1/4 eliptical spring [ like some Indians ] over the front. I will mock up both styles to see which is best. Cosmetically I want to try to incorporate the "Banana" styling cue ............

Hi TJ,

these are three different versions of front forks.
I can't see that any of those will work if you use the Bantam USD teleskopic fork.
I can only imagine the Springer lookalike version to work with that.
The "banana tube" can be shaped as you like, but the "guided" direction must be in parallel to the fork movement.
Any construction that moves in a section of a circle will not work.

Don't make it to complicated, just for the oldstyle look of it.

Cheers, Michael

Ouh, I love it!

so weird ideas, so crazy ways to mock-up.

As you say, TJ: Who needs CAD-CAM...

I am so curious how the result will look like. Go on!

Carsten