My Zbox 48cc HT Build!

Discussion in 'Frame Mounted Engines' started by kjparker, May 7, 2008.

  1. kjparker

    kjparker Member


    Here goes the story of my Zbox 48cc HT Build! I was spurred into action by seeing Impressions build, and finding out that the prices had dropped considerably since I last looked!

    I ordered my kit from Zbox at 6:15 am, and got the email from Warren at 6:30am with the con note number and despatch information. Cant beat that service! Irrespective of the product, thats customer service if I ever saw it!

    Kit arrived today, and it's as expected, all appears to be in order.

    I'm not in a super rush to get this together, I'm going to take my time putting it together, doing it right the first time!

    The bike that it's going to go into is a Giant Upland SE mtb, was a great bike to ride, very comfortable. I dont have it with me at the moment, it's at the bike shop being serviced, and having the bottom bracket and headset serviced as well, so that I know I have a solid starting point!

    I started by puling the engine out, and removing the cover for the sprocket, and the magneto to check for irregularities, all appears to be fine! I didnt have any trouble at all removing the screws that held it, Impressions motor must have been the exception, rather than the rule! I also wrapped the chain around the sprocket, and whilst it seemed to fit ok, I might take the dremel to it a little, and round off the sharp edges a little, but I reckon I could get away with it as is. I will post some pics of it and get other peoples opinions before I attack it!.

    I have also read that it's a good idea to put an o-ring in the carby where it fits to the intake, is this something I should be worrying about?

    My intention so far is as follows:
    • Replace all studs with high tensile hex bolts
    • replace all external screws with hex bolts
    • Permatex the magneto housing gasket, and seal the hole where the wiring exits the casing to stop water ingress
    • Loctite all bolts (what colour loctite should I use, I have read of different people using different colours!)

    I'll add to this list as things occur to me.

    Now the pics thus far! I'd be interested in peoples opinions and suggestions on the build!


  2. fastboy9

    fastboy9 Member

    Sounds like your know what your doing! I would definetely reccomend those upgrades you have spoke about, prevention is always better than cure! I'm using red loctite, only because thats all I've got, and it seems to be doing the trick fine. I like the big Z on the clutch cover! Also I would highly recommend replacing the exhaust nuts with nylon thread locking ones, I've put two on (the size is M6 or 6mm). And putting a split washer on it too. The exhaust will just rattle off otherwise. Also try and get hold of some strong rubber that can be used in between the mounts and the frame, this will make it a smoother ride and will be easier on your frame.
    Good luck with the build! Looking forward to seeing the result!
  3. impression

    impression Member

    hey glad to see you got it :D

    hurry up and get it ready for the Sydney meet :D

    Will_Start was a tremendous help with my build and he's not too far from you ;)
  4. kjparker

    kjparker Member

    Thanks for the responses guys:

    Fastboy9: Thanks for that, It's my first build, however I have done a lot of reading!

    Impression: I'm working on it, but I'm not going to rush it, however having said that, for the meet, the bike should be fine!

    Ok, now, some more plans!

    • Re-inforce the seat tube by pushing an additional seat pole down there for where the engine mount goes
    • investigate having the engine mount studs drilled and tapped to 8mm (maybe)

    I really should stop reading the forums, I keep finding more work to do! :)
  5. fastboy9

    fastboy9 Member

    yeah great idea about the 8mm studs, they definetely have to be replaced! I just spent about 7 hours drilling out and tapping a sheared rear mount, the stud sheared flush to the engine block!!
  6. impression

    impression Member

  7. kjparker

    kjparker Member

  8. BoltsMissing

    BoltsMissing Active Member

  9. kjparker

    kjparker Member

    Well, I just got off the phone to my local machine shop. It's going to cost me $30 AUD to have the mounting studs re-drilled and tapped to an 8mm thread. I have always thought prevention is better than cure, so I'll be getting it done now before I have any stud breakage!
  10. will_start

    will_start Member

    Good pics KJP,
    see you at lunch.

    I want to know if the petrol cap of Impression or kjparker leak.
    we were told by Warren the new Zbox caps should not leak.

    check this link.

    Impression you have a new Zbox, does it leak ?

    When I say leak, you get petrol spilling around the cap,
    enough to soak up a whole tissue.

    The motor has no grommet at the eletrical area,
    you should see if a hardware/auto store has one the right size,
    that killed my first magneto when I did an engine degrease.

    also don't use the kill switch, buy a toggle switch,
    I got a water-proof one from JCar.
    this link holds info on doing it.

    Just in case you were running out of things to do.
    Last edited: May 8, 2008
  11. impression

    impression Member

    Will_Start > The Tank lid i guess is better than the old one, but i still get some leakage from it though, only enough to smear around the tank and give it a nice "shiny black look". I Had to turn my bike upside down once when i had fuel in the tank and i lost prob 100ml's or a bit more and didn't even notice.

    With the included kill switch i have something that might interest a lot of people, i think i've hinted at what it was to Will_Start yesturday but we'll see how we go later on ;)
  12. kjparker

    kjparker Member


    A bit of progress today, no pics however.

    I took the engine to the machine shop, and spoke to them about getting the mounts re-drilled / tapped, they looked at it, and were very reluctant to do so, as ther wasnt enough "meat" to safely do so on one side, and the thickness of the casing on the other isnt known! Fair enough I guess.

    I went and bought some high tensile bolts though and hopefully I wont have a problem.

    I got the o- ring for the carby as well, might also look into sleeving the inside of the carby with the beer can trick as well, cant be too carefull!

    Managed to permatex up the magneto housing, hopefully I wont have a drama with water now!

    I took the clutch coever off, and noticed that I have two gaskets there??? Is this normal, or do I now have a spare?

    I get the frame tomorrow, so I should be able to investigate the mounting options then!

    More pics to come tomorrow nite after I have fitted the engine!
  13. impression

    impression Member

    looks like you have a spare.

    looks like you're also doing all the little extras that we found out first off before you start. that's awesome, I was impatient and just wanted to go :D
  14. will_start

    will_start Member

    patience is a virtue or some carp like that.

    PK your ride is going to be solid,
    can't wait til we go for a ride around the City.

    and you have yum chocolates,
    you need to bring a boxful to our day in the sun :rolleyes:

  15. kjparker

    kjparker Member

  16. will_start

    will_start Member

    a race to relaxation...

    kj, I wonder who will go faster in a race between the three of us.

    although I don't like the concept of racing these bikes,
    as it will be pushing the engine to extreme's, that could cause failure.

    maybe we should have a time-trial on The Day,
    to see whose bike takes the track quickest at the most comfortable speed.

    A race does sound fun ?
    hmm, we'll see, maybe we could have a most relaxed rider event.

    now i'm rambling.

    i was going to mention chatzy last nice,
    as you were both on.

    its used by the dudes here, on Sat morning.
    this can change, dependant on the post
    check General chat for updates.

  17. impression

    impression Member

    hehe, my bike doesnt like going @ slow speeds it gets jerky if i'm going any slower than about 15k's, weird :)
  18. will_start

    will_start Member

    i have felt such jerky actions,
    is it the chain tensioner that needs adjusting.

    its not the best if you always have to do 20km per hour.

    in trafficked areas you need slow control as well as fast,
    people can't always see/hear you to jump back.

    at the moment, I need to really rev my bike to keep it
    running at all. I think the tank boogers are building up
    and need some attention.
  19. kjparker

    kjparker Member

    One door closes, but another one opens....

    Well. Today didnt start out good. I picked up the frame, and found that the tubing was way too big, on both tubes. Not going to happen

    On the way home it got me thinking though. On sheldon browns website, I saw he had put suspension forks on a road bnike from a mountain bike.

    I have a spare pair of suspension forks. I also have a spare road bike frame.

    Just to see if it would all fit, I tried the mtb wheels in the road frame, after cold setting the frame slightly in the rear, the mtb wheel fitted! I also cold set the forks as well, even though I'm going to change them, to see the front wheel go in.

    After that, I test fit the motor! It fitted! I had to space out the rear mount with some washers, but it bolted up!

    Now the problem. The cracks only clear the engine by a few mm. I wonder if I can grind a couple of mm off the back of each? giving enough clearance that way. Thoughts?

    I also intend to fit a set of flat bars, and to also run it as a single speed. if it's going to be an oddball bike, why not make it real odd! :)

    Pics of the frankestein bike shortly!


    I might use some fixed forks I have for now, keeping the suspension bike intact for now. PIcs following of both!
    Last edited: May 11, 2008
  20. kjparker

    kjparker Member

    ok, I noticed that the tube on the forks isnt long enough, so the road forks will need to stay for now, until I find some MTB forks with a long enough stem.

    I fitted the handlebars to see how it sits, and it looks like it will have a nice riding position, surprising enough, and given it was a racing fame, is relatively light!
    Last edited: May 11, 2008