The Pocket Bike Engine and Your Opinion...

Discussion in '2-Stroke Engines' started by conradcliff, Nov 12, 2008.

  1. conradcliff

    conradcliff Member

    Ok, so I've been posting bits and pieces of questions and info about these 47cc pocket bike engines all over the place and I thought I would wrap it all up into one dedicated thread.


    Just as a precursor, and although I appreciate the concern, I've pretty much got the mounting and gearing all figured out. I plan on rack mounting the engine and running it to a jackshaft just like the SBP kit and then to a freewheel crank just like the SBP kit and then back to my hub gears just like the SBP kit.
    What I'm hoping we can do with this thread is lay down some solid experiences with these pocket bike motors and determine what kind of reliability one can epect from them.

    Some of the advantages to these engines is that they are cheap, have incredible parts availability, can be upgraded like crazy and they look cool to boot.
    Some disadvantages, well, I don't really know. That's what I'm trying to figure out. I pretty sure this engine in particular does not have a cast iron sleeve like the GXH50 (which is my other option) so it probably wouldn't last quite as long, but I wouldn't be suprised if you could find an upgraded cylinder with a sleeve considering how many parts are available for these things.

    In summary, what do you think? Have you owned one either on a pocket bike, a motorized bike or anything else for that matter? What can you say about the characteristics of these engines, are they powerful, are they reliable or are they just plain finicky pieces of junk?

    It's waiting on your opinion that keeps me up at night, so please drop a line if you've got some time..hey that was almost a rhyme! :lol:

    Thanks for any help, you guys are great! :D

  2. fastboy9

    fastboy9 Member

    The pocket bike engine is surprisingly powerful and will beat a happy time easily! You can buy big bore upgrade kits too which will give you a CNC machined cylinder that will make the engine last a lot longer. As long as you look after it well then the advantages definetely outweigh the disadvantages. Go for it!

  3. conradcliff

    conradcliff Member

    Freakin sweet! Thank you so much for the reply! Yeah, according to the description the one I'm planning on purchasing already comes with the 44mm big bore upgrade and some other things. I think you've pretty much just pushed me over the edge!

    Thanks again!
  4. fastboy9

    fastboy9 Member

    No problem! that bike is going to be a screamer! cant wait to hear more, the list of upgrades is crazy, 11hp is pretty easily obtainable and the parts are so cheap for what you are actually getting. I think the record top speed on here is by a guy called kawasaki 999, he has a GP460 engine which is usually for go-peds, these engines are only 4.2bhp and his goes 55mph!!! so a fully modified engine up to 8hp, wow that would just be amazing, that plus gears omg.

    Last edited: Nov 13, 2008
  5. nathanl

    nathanl New Member

    That is tempting. Not a whole lot of information on the page though. Can't see the mounts, do they mount in a similar way to the happytime? I guess not since you're going with a rackmount? Also, what sold me on the happytime was the built in gear reduction, anything like that on this engine? The page doesn't say much about it!

    Edit: I got curious and found haggard's thread on it, looks like you need external gear reduction and no easy frame mount options. I'm terrified of fabricating a jackshaft so I'll stick with the happytime, but go for it if that's something you can handle! That will be an awesome bike!!!
    Last edited: Nov 13, 2008
  6. conradcliff

    conradcliff Member

    I can't wait to see what happens! It wont be long now, I'll have the bike by next week and once I give it a looking over and make sure everything is going to fit I'll be ordering the parts. This is gonna be fun!
  7. Mountainman

    Mountainman Active Member

    I am also wondering about the outcome for you with this engine

    thinking about a fast MB THING for my next build

    ride that thing
  8. conradcliff

    conradcliff Member

    I can't wait to get started on it. I'll be making a detailed thread of the venture with plenty of pictures once I get underway..
  9. ocscully

    ocscully Member

  10. nathanl

    nathanl New Member

    This was probably answered before, but I am being shoed off the computer, Would the pocketbike engine be able to mount to a grubee 4 stroke style frame plate? (Anything is possible I guess, but without severe modifications?)
  11. conradcliff

    conradcliff Member

    Yikes, I got spooked about ordering one of these by one of the guys on the pocket bike forum I joined..he says it wont be that reliable and I'll end up paying for it.

    Anyone got any first hand experience with these things?
  12. mechcd

    mechcd Member

    I'm the wrong person to ask but here goes

    I have very little run time on mine.

    The biggest problem I have is starting. Its about 30 degrees outside, so starting any small engine poses a challenge.

    When it was warmer outside, I had difficulties getting it primed. This was mostly due to me disconnecting the gas tank every time i put it away. I got a primer bulb and would hook it to the overflow tube until i could see fuel in my clear plastic filter. Then i would take it off and throw it in my pocket.

    You absolutely want to go get a new spark plug. Champion, Bosch, Autolite - anything other than what it comes with.

    I would also like to hear from anyone that has had one of these for a while. Parts are plentiful and cheap, but replacing stuff every week would be a pain.
  13. conradcliff

    conradcliff Member

    I hope that I wont have to deal with those issues as I am in Florida and hope to keep the Fuel tank connected.

    Thanks for the info! :)
  14. djase10

    djase10 Guest

    Hey good 1, sounds like its on the move for you.

    My pocket bike powered stingray is madass, i love it.
    The motor is TOUGH, handles the extra revs no worries.

    the only dramas really is it is a PIG on fuel. Just drinks it.
    bent axle from the power.
    So its a weekend ride only.
    & I use my HT 2 strokes for every day rides.
    All the best with your build.
  15. conradcliff

    conradcliff Member

    Yikes, what kind of gas millage do you get? And what axle did it bend? Was it a jackshaft? If so what was the OD and length..I ask because I just ordered all my stuff and I want to make sure I don't bend anything.

    How do you have it geared up also?

    Thanks for the info!
  16. Mountainman

    Mountainman Active Member

    well -- we wish you good luck with that one

    bet it will be more than a fast THING

    keep us informed -- pictures once it's THING in

    always excited when we are waiting for the THING to come in

    ride that THING
  17. mechcd

    mechcd Member

    I forgot I blew out an axle too, but it was a cheapie stock one that was already worn out. I doubt the engine had anything to do with it. The threads were worn and partially stripped. i couldn't keep the cone bearing snugged up enough and everything wobbled.

    Djase is right about the fuel. I finally got out and rode around for about 30 mins. I ran out of gas twice in 8 miles :rolleyes7: There was a significant amount of spillage out of the vent too. New gas tank time?

    The tank is somewhere around 6-8 oz and is for a chainsaw, a bit too small perhaps.
  18. conradcliff

    conradcliff Member

    Thanks for the reply..the fuel consumption is a big issue for me so I have pretty much decided to use the Titan with one of the pocket bike clutch bells..I don't suppose anyone could get the measurements center to center for the mounting holes off of the clutch bell housing for me? I would really appreciate it and would be your best friend! :D
  19. mechcd

    mechcd Member

    I have a 2d drawing somewhere.....

    Forgive the metric measurements

    It's 70 mm center to center on the mounting holes. And also 35mm from the center of the bell.

    the holes are around 9/32
  20. conradcliff

    conradcliff Member

    Thanks a ton for your help! I'm going to be ordering the last pieces of the puzzle very soon.