message to beginners

Discussion in '2-Stroke Engines' started by jaguar, Aug 17, 2016.

  1. jaguar

    jaguar Well-Known Member

    I am a very experienced 2 stroke guy and I have good news and bad news for you.
    The good news is that with a few tools and a bit more investment you can have a really good ride.
    The bad news is that as is the new Chinese two stroke (48cc and 66cc) is poorly designed and needs some parts machined and some parts replaced.
    Things you need to do:
    1. Use sandpaper on glass to plane the head surface flat and increase its compression a little bit for more power. Also make your own head gasket out of high temp gasket material for it to seal properly.
    2. Drill a bigger hole in the wrist pin for less vibration. Without this the engine will always be unrelible as it will shake loose nuts and bolts. Also a vibrating engine makes it uncomfortable to ride. If it still vibrates too much then you need to drill holes into the crank wheels with a 3/8" carbide bit.
    3. Take the screws off of the stator coil and clean off the shellac on those screw head contact areas. That is important because that screw to metal contact is the ground path for the high voltage coil and spark plug. The worse the contact is the weaker the spark will be which reduces engine power.
    4. Replace the stock nuts/bolts/studs with a replacement kit from Sick Bike Parts. The stock ones are too buttery and will strip threads and break off. Also apply medium strength thread lock to all threads.
    5. Lower the needle in the carburetor to the limit because the stock fuel to air ratio is too rich and will make the engine run rough and with less power. It will also cause plugs to foul and stop sparking. You will also need to buy a micro drill bit set and melt solder into the main jet and then drill it out to a smaller size. The stock main jet hole is too big and makes the engine run rich at full throttle. Also make sure the float stops fuel flow at the correct level which affects the fuel/air ratio.
    6. Replace the restrictive stock air filter with a bigger foam one that needs to be oiled with engine oil before installing. This will let the engine breath better for more power. The stock one is too restrictive and causes the fuel/air mixture to be too rich.
    7. Replace the stock spark plug with an Iridium one (#7 for moderate climates or #8 for hot climates). This gives a more consistent spark at a lower voltage for smoother more powerful running.
    8. Put a fuel filter on the fuel line because the filter inside the gas tank won't filter out the finer particles. Also there's usually trash inside the fuel tank that should be cleaned out before use. If not then that will partially block the filter and limit fuel flow.
    9. Once you get these mods done and want the engine to start easier, run smoother, and have better top speed then think about putting a good carburetor on that is fully adjustable with an idle jet as well as a main jet. Also a good aftermarket CDI will help in the same way.
    10. Consider removing some of the baffles in the stock muffler for better top speed.
    11. The most technical mod you can do is buy a rotary tool with cutting discs and mod the cylinder ports for more power. You can widen the intake and exhaust ports and lower the intake port (or take some off the bottom of the pistons intake skirt) so that it has a bit longer open port duration (120 degrees) which gives it more power all around.

    All of these mods are fully explained on my sites pages. Click my signature link and start reading.

  2. bakaneko

    bakaneko Active Member

    or get a 4 stroke and do nothing ;)
  3. jaguar

    jaguar Well-Known Member

    yes they are built better and are more reliable but you are stuck with them as they come with low power output. To get more power you have to make your own competition camshaft which no one on this forum can do.
    For the same RPM a 4 stroke outputs half the horsepower as a 2 stroke because it only has one power stroke every 4 strokes whereas a 2 stroke has one power stroke every 2 strokes.
  4. Island Racer

    Island Racer Member

    "" Drill a bigger hole in the wrist pin for less vibration ""

    You mean length wize, to make the pin lighter in weight what is the wall thickness before & after drilling the pin out ??

    That would work .... Got a picture before / after please ??

    QUOTE " Replace the stock nuts/bolts/studs with a replacement kit from Sick Bike Parts. "

    I replaced most bolts with stainless steel ones, just from the hardware shop on the corner ... Works good .. looks good ...
    Last edited: Aug 18, 2016
  5. jaguar

    jaguar Well-Known Member

    of course it works. I did it myself. It lessens vibration but only partially. the full cure is drilling the crank wheels. all is on my site, including dimensions.

    you need to replace the cylinder studs and the frame mounting studs. buy the kit from SBP.
  6. Island Racer

    Island Racer Member

    Ok i will drill the piston pin out ... That's fun to do ..

    I made my own frame mounting, and re tapped the 4 mounting holes with M8 galvanised 8.8 bolts

    All other bolts like cylinder struts I used Stainless, looks clean and cheaper then ordering from some company ..

  7. Frankenstein

    Frankenstein Well-Known Member

    Those are some good looking mounts, I'll tell ya that
  8. CrazyDan

    CrazyDan Active Member

    Beautiful mounts. Ever think of making a few dozen and selling them?
    bigkev81 likes this.
  9. Island Racer

    Island Racer Member

    No need to sell, I give the drawings for free ... Hubclamp & engine mounting

    Look up the thread " tinker time " I put the drawing on there, you only need to check the dimensions for tubes and engine mounting

    Note that I drilled out the 4 engine mounting holes from M6 holes to M8 tapping ...
  10. Island Racer

    Island Racer Member

    Here are the drawings, please use them we are here to share and make things CHEAPER ... and we all know cheap is good ...

    note the hubclamp is made from PIPE & plate And the inside of that pipe machined to be just a bit bigger then the hub .... note I use 2 m6 nuts between the rear sprocket and that hub bracket for setting the rear sprocket all around the same ... Works perfectly ... It's a pAiN to install though ....

    I use 3M tape between all the connection points, strong as bull shat stuff,

    Note also that the stock exhaust does not fit with this bracket, so I made a flexible exhaust hose .... The exhaust gasses spray the chain with 2-stroke oil so I do not need to oil my chain any more ....

    14705505322991819319526.jpg IMG20160530131439.jpg IMG20160331105529.jpg IMG20160331105537.jpg
  11. Frankenstein

    Frankenstein Well-Known Member

    This is great I'll say that at the least, but the problem is not many people have access to machining equipment or welding equipment at a fair price. I'm fortunate enough to have either the skill or equipment/people available to me who/which can make these simple feats actually simple. This is why people will buy your "product" simply because it's not possible to get them otherwise at a good price if any price (think Joe schmo living in the middle of no where and he's only good at growing vegetables and so is everyone he knows)

    I mean I COULD work up the means to get a set of mounts like yours, heck I don't even need your drawings it's a practical self forwarding idea that I could draw up half drunk in a strip club if I wanted those drawings bad enough, perhaps with a bit more pizazz thrown into it for looks, but I would much rather see you benefit from the idea knowing firmly you know exactly what to do without thinking about it and it will work, and all I have to do is pay you for it. Meanwhile that frees up my strip club/drunk time and I also don't need to aquire the supplies (which would naturally be rigorously researched and over researched for the best materials, and compared over a compiled list consisting of a hundred different values and ultimately wasting even more of my time than necessary, what'd you expect from an engineer otherwise) and whatever else needed to complete the task so that we can all sorta move on with our lives.

    Just set a fair but inflated price, this way it's worth doing it even if you hate the idea of doing it for money and rather they do it themselves (which is a concept I completely and totally understand and empathize with, damn stupid people) and if they think the price is too much then they can figure out the rest themselves. :)
  12. Frankenstein

    Frankenstein Well-Known Member

    To put it simply, there's bikers, then there's Rolex bikers, only one groups gonna pay you, may as well make them pay for your Rolex too.
  13. Island Racer

    Island Racer Member

    Sitting on a beautiful beach in Israel after a hard day's work .. reading your post with a beer under a parasol i must say I LOVED YOUR POST ... Smiled a lot too ...

    ha ha ha ha

    Shipping would "kill" it for me, as I live on a small island in Indonesia ... And anything I post I must do from Singapore, so it is quite the endeavour posting stuff here ...
  14. JunkyardDog

    JunkyardDog Active Member

    Some good information. I used to modify 49cc moped engines, mostly Puch E50 and Tomos A35.

    Those are nice mounts, but not universal. You would need to machine the mount to fit the specific frame tube diameter to make it work perfectly. And even then, the tubes would have to be straight, not tapered. They are making bikes with some pretty weird frames these days. There are also a couple of other issues to building a quality bike with a frame mounted motor, whether 2 stroke or 4 stroke. The rag joint rear sprocket and clamp on tensioner are absolute garbage. I would use a clamshell rear sprocket mount, and an engine mounted chain tensioner. More expensive yes. But you will have a much nicer and far less dangerous bike.

    I still wish someone would build a complete motorized bicycle where everything fit perfectly. Something like the recent Whizzer, only with a 48cc motor to make it legal. The Whizzer was never legal in my state. I also wish you could buy quality parts to build a motorized bike from, including frame, wheels designed for a rear sprocket, engine mounts that would fit the frame perfectly, forks designed for V brakes, etc. Motorized bikes have been around for a long time now, but you still can't get any properly fitting high quality parts. It is virtually impossible to build a motorized bike without having to rig something. Not enough of a market? Maybe. But before they became illegal almost everywhere, you could get a lot of high dollar parts for gopeds, and right now there is an absolutely HUGE aftermarket for the Honda Ruckus scooter, which costs about $2000 new. I have seen people put $10K into one. You can actually build an entire Ruckus out of aftermarket parts. Same thing exists for many mopeds. Check out, and They are now building custom frames for the Puch and Tomos engines. Why doesn't the same thing exist for the motorized bicycle market?
    Island Racer likes this.