HT ZBOX F-50 install into Cruiser


New Member
Local time
4:18 PM
Jul 15, 2008
Perth, Western Australia
Hi All,

I stumbled across the site a few weeks ago and thought it looked like a fun project to make my own motored bike to ride to work on, so ordered the kit and searched around for a suitable bike to transplant the engine into. Found a $149 triangular framed cruiser with rear hub brakes that would do the job at a local bike shop so brought it home and got to work when the kit arrived.

I spent a lot of time trawling the forum for tips and info and here's what I've done to 'optimise' this install:-

1) Loctited every nut/bolt on the bike/engine/carby (except the ones that need to move for adjustment ie. fuel mixture etc)
2) replaced all the mounting studs with hi-tensile bolts of correct length
3) made a custom front mount out of an exhaust clamp and steel plate
4) replaced the head studs (torqued to 12ft/lb), intake manifold and exhaust studs with hi-tensile bolts
5) bent the exhaust to make it fit
6) bent the chain tensioner to align it with the sprockets
7) ground down the square edges on the front sprocket with the dremmel
8) lubricated all the cables
9) installed an o-ring in the intake manifold where the carby attaches
10) trued the wheels
11) sealed the magneto housing with hi-temp silicon
12) replaced the engine case bolts with hi-tensile ones
13) installed a fuel filter and wired all the fuel line joins so they don't leak
14) modified the rear hub brake arm to fit over the sprocket
15) lightly greased the gears with lithium grease
16) greased the clutch mechanism
17) taped up the carby cable with silicon tape to stop air leaks
18) replaced the spark plug with an NGK B6-HS gapped to .028 (about 6.8mm) slightly wider than as it came

there's probably more, point is I used the resources on the forum and took my time to make sure the bike is reliable once run in

All is left to do is to mix up some fuel and go riding (hopefully tonight!)

Pics below












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that is a very nice build. it is easy if you can read. i am floored by questions like, my tire is low should i put air in it? and others that seem to indicate this person should never be let out of doors. now lets ride.
well it started up first go and I ran it for about half an hour on my bicycle trainer (supports the rear wheel and provides resistance via the wheel rim rollers) as it was raining out.

It quite quickly loosened up and got easier to start - is that normal? Seems like it has less compression now than when it was unused.....but it did run better by the end of half an hour on the 'dyno' I must admit.

Only thing I noticed at wider throttle openings it seems to drink more fuel than the flow can keep up with and I had air bubbles appearing in the fuel line. Maybe its the filter restricting the flow but I wouldn't think so as its a Motorcycle filter I used which is designed to work on much larger capacity engines. Any ideas?

Otherwise ran well - the engine rattles more than I thought it would but as I've not got anything else to compare it to, I wouldn't know if this is normal or not yet. Am building another one with a mate so will see what that one turns out like.

very clean build, I especially like the engine mount. how long did it take to put together? Are there any hurdles you encountered, also what kind of speed to you see in its stock form (44tooth?)?
Took about 10 hours because I was working slowly and there were a few trips to the shops to get bits and pieces for the build. main hurdle was fitting the rear sprocket over the coaster hub (bending the brake arm) and bending the exhaust to make it clear the frame - that took a bit of effort with the exhaust sandwiched between wood blocks in the vice.
I figured out why I had a loss in compression after the first test run....the head bolts were quite loose. I was suprised at how quickly they lost their tension - I guess its because of gasket compression and the bolts stretching a little. Hoping that they'll settle down and not require retorquing every 2km going forward. Fuelling seems to have sorted itself out now too as had a run around the block tonight and it went well.

I also put a piece of Neoprene rubber (wetsuit material) inside the gear casing to insulate the noise coming from the well and doesn't hit the clutch plate so all good. I see on the forum some people use card board as well.

Not sure on the top speed yet, because I have been keeping it around 20km/h as recommended during break in.
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when you say replace bolts with high tensil ones.... i dont know that term... is it something that can be found at a normal hardware/home improvement store or do you have to go to a bike shop the way that is a super clean machine
High tensile strength bolts I am referring too - the metal is harder and stronger than softer metal bolts. Some home improvement stores have them, others may not. I got them from a specialist bolt shop as the size is quite specialised - 6mm x 100mm 1.0 thread pitch.
Love the build and the pictures are great.

I'm having real issues with the motor mount. I can see what you did for the front but could you post a picture or more for the rear mount?

I would greatly appreciate it!!!!