Refurbing bike, spark plug

Discussion in 'Electrical' started by aceofspades, Mar 29, 2016.

  1. aceofspades

    aceofspades New Member

    got a motor bike. The spark plug it came with doesn't match the standard replacement. Is virtually the same as champion marine so I got one and gapped it at .42. However the post is larger and doesn't use screw type. Should I just file it down. The post screws off but that doesn't really help.

    Also I got replacement intake for speed bottle but the stock is 2 bolt. I just drilled the stock one and jb welded the tube on or should I jb weld the brass fitting. Will the heat melt the tube? I guess I'll figure it out once I ride it around lol

    Also it doesn't have non drive side pedal, probably because it didn't clear. Might try and find a new pedal bar. How do I get it to clear.

    Finally how do I install a pull start.

    I put a rocket racing CDI, will it handle a 6v light bulb?


  2. HeadSmess

    HeadSmess Well-Known Member

    spark plug, mark hug...

    as long as it threads in, without having the longer "E (ngk)" thread, it will get you going. get an ngk br5(6,7)hs, or borrow something from the lawnmower/line trimmer etc...

    no probs if you file the nipple to size, if its a solid, non screw one. might even hold better than normal, the boots dont really cling on that well anyway.

    manifold shouldnt be getting that hot, though really its better to at least try using electrical solder rather than jbweld ... steel and brass both solder very nicely as long as theyre clean (file, steel wool, pool acid, etc) though of course its no good if its an alloy manifold. better yet, dont bother with "boost bottles".

    getting the pedal/crank to clear can be a nightmare if it doesnt fit but the engine should be fine, even on a skinny cranked racer. i would just take the magneto cover off if it is hitting, but you could always try and find a longer bottom bracket axle (ebay). dont even contemplate cutting, bending or similar... can grind a few mm off the back of it, but no more. can try repositioning motor, some frames they sit low, most frames they clear the cranks altogether.

    pull start is even wider. why you want pull start anyway? something else to go wrong, dumping the clutch works fine. (break a starter cord and you cant start at all)

    cdi doesnt take any light, only certain magneto will do that and they burn out and arent readily available anymore, but there are aftermarket coils for 12v...
  3. 45u

    45u Active Member

    I would not run a boost bottle as they do nothing but look good. Talk to anyone who races RC cars and trucks and you will see. I use to race them.
  4. HeadSmess

    HeadSmess Well-Known Member

    while i also agree they serve no purpose (unless designed correctly) talk to anyone that races nsr250's, kr250's, yz250's, um.... quite a lot of production 2 stroke motorbikes and quads and other things with twostrokes...and they will gladly show you the factory fitted "boost bottles"... they dont call them that, but thats what they are. big (tuned) resevoirs on the intake manifold.

    and some of those engines are completely untuneable/unuseable without them...
  5. Frankfort MB's

    Frankfort MB's Well-Known Member

    Lol those bikes are 3 times the size of a HT engine and just cause they use it doesn't mean that a engine with 4 horsepower on a good day is going to make a difference
  6. 45u

    45u Active Member

    Stock these motors do not have close to 4HP at the most 2.75 if that. I have done quite a bit of testing on boost bottles on my 1/5 scale radio control cars and if anything they did not run as well. All my 1/5 scale motors I have are putting out no less then 4 or 5 HP.
  7. Frankfort MB's

    Frankfort MB's Well-Known Member

    I meant when they have upgraded everything they are lucky to make 4or5 HP
  8. 45u

    45u Active Member

    Folks are able to get 5 to 7 and more out of a 32cc RC engine I think you should be able to get at least that out of the China 70cc done right. I all so think if you go as far as have good plating on the cylinder and run a wrist pin bushing instead of a bearing it would hold together for a while.
  9. HeadSmess

    HeadSmess Well-Known Member

    all these engines are piston ported, i am assuming.

    just like the HT.

    you will only see "factory" boost bottles on reeded intakes. not someones hashed up piston port-to-reed conversion, but on factory produced reed engines.

    i still think they are a waste of time too ;) unless already installed, in which case...i leave them alone!

    these china things just dont have the breathing potential to get power from... not a matter of plating of bearings...they have asthma and bronchitis from birth! possibly some pneumonia chucked in as well... emphysemia? definitely...