HT ZBOX F-50 install into Cruiser

Discussion in 'Frame Mounted Engines' started by Wilmo, Jul 16, 2008.

  1. Wilmo

    Wilmo New Member

    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












    Last edited: Jul 16, 2008

  2. stude13

    stude13 Active Member

    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.
  3. Wilmo

    Wilmo New Member

    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.

  4. mbatl

    mbatl Guest

    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?)?
  5. Wilmo

    Wilmo New Member

    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.
  6. Wilmo

    Wilmo New Member

    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.
    Last edited: Jul 18, 2008
  7. frankz

    frankz New Member

    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
  8. Wilmo

    Wilmo New Member

    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.
  9. adumas

    adumas New Member

    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!!!!
  10. Wilmo

    Wilmo New Member

    There is no modification to the rear mount, its as it came with the kit, that is a 25mm seat post tube so the standard mount just cups it nicely.
  11. Stink Bike

    Stink Bike Member

    It will get easier to start after you have done the 500k run in.
    If it seems to be starving for air try loosening the petrol cap.If that fixs the problem you may need to drill a small hole in the cap to allow better air flow.

    To reduce engine vibrations cut a sparkplug lead into 1/4" lenghs and jam it in between motor fins.This stops a lot of vibration and noise.
  12. djase10

    djase10 Guest

    A very tidy build you have there mate.
    mud guards round it off nicley =good1.
    Regards Jase
  13. fatboy67

    fatboy67 Member

    Very nice build.
    Hey I like the mud gaurds I want to get a set did you get them here in Aus??
    I want to get a set.
  14. Wilmo

    Wilmo New Member

    Mudguards came with the bike. Its an Indi 'Cruz'.
  15. mbatl

    mbatl Guest

    How is the bike running? Any cool riding stories to share?
  16. Wilmo

    Wilmo New Member

    Its going really well! Now I've done 150km's on it, and the head bolts have settled down, needing less frequent tightening to the proper torque spec. Had to replace the fuel line, as fuel makes that clear china spec line (in my pics) brittle and it fails with the vibration. Don't use it! Also removed the o-ring in the inlet manifold where the carb mates to it, as I discovered that the fuel softened it. Still seems to run the same without it with no air leaks.

    The thin metal exhaust 'mount' that you strap the exhaust to the frame for support fractured from the vibration at the bolt hole. So I bought a galvanised steel gutter strap (for fixing a gutter down pipe on your house to the wall) and bent that up to use instead, and that is working much better. Much thicker metal and about three times the width. Also isolated it from the exhaust and frame using silicon 'rescue tape', which can withstand temps of 400 degrees celsius, and that dampens the vibration.

    Had to play with the needle position to get the carb tuned perfectly, but now its pretty good. Also repositioned the chain tensioner and tightened it up (using lots of loctite) and that is also fine now. Now the teething troubles have been sorted it seems like its going to be fairly reliable, touch wood!

    It cruises very comfortably at 25km/h, sits on 30km/h reasonably well, and I've had it up to 35km/h for a brief stint recently, where the motor just comes into its power band. Sounds like its working hard there though and you probably don't want to run it hard like this all the time. I'm careful not to let it over rev without fuel (closed throttle) when going down hill, and just pull in the clutch lever and coast down hills. Its good insurance.

    Most people I see on the street have never seen a motored bike before and I get some amazing looks. One of my wife's friends whom I see pushing her baby around in a stroller occasionally just laughs when she sees me! :-( Kids in the street just stop and go 'wow' and wave! I rode it into town the other day for the scrutineering of the Australian Safari competitors (off-road motorbike desert race) and a couple of the service guys (I am one too) were very impressed and were going straight home to look up! Funny how my 3hp motored bike drew more interest than the latest KTM 690 Rallye bike fully kitted up!

    I'm lovin' it!
    Last edited: Aug 19, 2008
  17. Keep a close eye on those fenders, and mounts. The same tends to happen to the fender mounts that happened to the muffler mount from vibration, and can lead to a nasty wreck....
  18. BoltsMissing

    BoltsMissing Active Member

    Credit to ya mate, nice clean build.
  19. arceeguy

    arceeguy Active Member

    That is a very professional build! Kudos mate!