newbie here with 1st build questions

Discussion in '2-Stroke Engines' started by dotcom, Jan 20, 2014.

  1. dotcom

    dotcom Member

    I've been riding my new bike build now for about a month with minor adjusting here and there but nothing major. I paid $140.00 for the kit, $100.00 for bike, $70.00 for upgraded carb, $50.00 for upgraded heavy duty back wheel, tire and innertube. I know little about motors and am wondering a few things. I recently got the new high performance carb "with jets" to replace the stock China "80cc/66cc" carb but it seems I am going a tad bit slower than with the stock carb especially, on take off. Not much slower but the bike has a max speed of approx 22mph which ends up about the same from the stock carb. I weigh about 265 and the bag I carry usually weighs 15-20 extra pounds.I thought the new carb it might increase the speed alittle as well as help with consistent fuel air flow but thats how much I know about this stuff....:) On flat road I max 21-22mph and can go 19-20 smoothly on longer distances.... I thought id be able to reach 30 but I was wrong. Climbing is a task at about 8-9mph max and struggling. I am wondering what the best thing to do for that is. I was told something needs to be "bored?" but I do not know how or haven't looked into what that complete process consists of. I was hoping someone could shed some light on the subect. A specialist that fixed my bike a couple times that is about 40 miles away said if I put about $150.00 into it, theres a few upgrades that they can do to definitely increase the speed a bit so I figured I would try and do it on my own. My speed goal for this bike is 30+

    Another question I have is; I was thinking of starting a 2nd build with a harbor freight motor but does anyone sell a package kit for the rest of the parts needed without the motor for one of those motors?

    Lastly, whats the best thing for the heavy duty motor chain for cleaning and keeping lubricated?

    Thanks for reading and check out my first motorized bike below :) I just cleaned er up yesterday. (Purchased from boygofast on ebay. Great seller!)

    onward and upward!


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    Last edited: Jan 20, 2014

  2. Fabian

    Fabian Well-Known Member

    The carburettor (given the same venturi diameter) as the standard carburettor will not give any increased power, because physics dictates how much air can be drawn through a hole under a given pressure drop (provided by the engine) at maximum safe rpm.

    Even if you do install a carburettor with a larger venturi diameter, the engine will then be restricted by internal diameter of the intake tube.

    These engines are what they are, and the best option is to improve low and midrange torque to improve drivability rather than outright power.
    Aside from installing a tuned exhaust pipe, you can modify the standard muffler to slightly increase power.

    My bike has just about all of the modifications that you can throw at these engines (CR Machine Manufacturing billet cylinder head, Rock Solid Engines reed valve intake and Walbro style carburettor, Jaguar CDI, Magnecor Ignition lead, modified cylinder, modified exhaust) and it still won't go any faster than the speeds being achieved on your bike.

    It does however have tremendous midrange torque compared to a standard engine, allowing me to use much lower rpm to achieve similar speeds, making the bike much more pleasant to ride, not only from significantly reduced vibration but from significantly reduced noise.
     
  3. V 35

    V 35 Member

    Engine needs to break in, takes time

    The China motors need a few tanks of gas to break in. Mid range torque, and driveability improve considerably after break in.
    Pay careful attention to clutch adjustment, a slightly slipping clutch can rob power.
     
  4. dotcom

    dotcom Member

    V 35- As soon as I start the engine after the pedal start there sounds and feels like a slip somewhere. I think it might have something to do with the electrical kinda like a car does but again, im not sure. After that initial slippage, it seems to be perfectly fine. I do not know if that is normal or not since I do not know these things very well. But now that you mentioned the above, I am considering it might have something to do with the clutch pads slipping on initial start up but it's been doing that since I first got it. It has not changed performance-wise like, got a lengthier pause or gotten worse. But again, now that you mentioned that to me, I am wondering what that is. I do not notice other bikes like mine doing that.. I am on the 4th tank refill on the same 16:1 ratio. The next tank refill I need advise for. I live in Sunny South Florida where the weather is almost 75-80 degrees all year round and i've heard the weather might have something to do with the way the ratio should be mixed. I need expert advise though
     
  5. dotcom

    dotcom Member

    whats the best muffler? and a good fairly price alternative to buy performance-wise for these kits?
     
  6. Fabian

    Fabian Well-Known Member


    There is no such thing as """the best muffler""" because the best exhaust system configuration will depend on the type of riding you do and the rpm range you operate the engine at.

    The forum member Jaguar makes a version of a tuned exhaust pipe that focuses engine performance on maximum torque, though i cannot verify this claim as i have not tried it on my bike.
    The vendor SickBikeParts sells an exhaust expansion chamber that is claimed to give good overall improvement in power, but again, i cannot verify their claim as i have not tried it for myself.
     
  7. Fabian

    Fabian Well-Known Member

    Don't be too concerned with 16:1 ratio for break-in.
    I have had good results with 25:1 from the word go, using the cheapest air-cooled specification 2-stroke oil that i can find, and typically get 4,000 kilometers (2,500 miles) before piston, rings and cylinder need to be replaced.

    The most important thing is not to run the engine with a lean air/fuel mixture.
     
  8. V 35

    V 35 Member

    The clutch cable should be checked for a little slack, and no binding, [ lever released ] before adjusting clutch

    Remove right side cover, the clutch is the big, round, drum . At the center, is the flower nut, and retaining screw
    Mark the nut and retaining screw [ paint marker best ] Remove retaining screw, tap flower nut 1 dentent away from retainer screw hole
    [ clockwize ] Squeeze clutch lever, should be ' a little ' stiffer now. When you feel clutch is right, replace retaining screw, mark new setting, replace cover, and re-adjust cable, if needed . The clutch plates take a ' set ' after a few dozen heat ups / cool downs after fine tuning clutch, go back to tuning carb.
     
  9. dotcom

    dotcom Member

    is WD-40 a good option to lubricate bike chain AND motor chain? And a good option for a chain cleaner from, lets say Walmart?
     
  10. ez dave

    ez dave New Member

    chainlube is the best, wd is a little to thin, but makes a great cleaner. chainlube is available at most auto stores. a truly nasty chain i'll clean with brake kleen.
     
    Last edited: Jan 29, 2014
  11. ez dave

    ez dave New Member

    i ran a 66/80 with an expansion chamber jetted carb and a 36 tooth sprocket and would see 45 mph. i live in florida with relatively few hills. im also 240lbs so these gains were impressive. as far as internal motor work i'd stay away until the time comes to tear it down anyway, you know the old saying if it aint broke.
     
  12. ez dave

    ez dave New Member

    i had the sbp chamber and it does work well, though a little pricey.
     
  13. dotcom

    dotcom Member

    question- would a 32 tooth sprocket be better that the stock china kind that comes in those kits? If so, why and would it do harm to the engine as well as make the bike faster
     
  14. V 35

    V 35 Member

    In the interest of safety, consider this ... A Pineapple Joint sprocket [ comes with kit ] only supplies torque to one side of the wheel,
    a ' real ' motorcycle supplies torque evenly, to all spokes . A wheel that only sees one side torqued, will warp. The China Girl kit sprocket is poorly made, same with the chain. If you value safety, and reliability, upgrade to a 2 piece hub sprocket, and a better grade of chain .
    BMX chain works well with many sprockets. As for sprocket size, the big sprockets make for good off the line punch. The 36 tooth ' powerbands at about 6 MPH up making it a useful bike. I've got a 42 tooth, slow [ 25 MPH ] but climbs hills . A local guy has a 24 tooth rear sprocket, his bike doesn't powerband until 20 MPH, can do over 50 MPH, and can't climb a gentle slope
     
  15. dotcom

    dotcom Member

    which would perform better?
    1: 80cc china kit
    2: harbor freight 79cc engine kit?
     
  16. V 35

    V 35 Member

    What are you asking ? An 80cc engine kit is the raw basics. A better chain / Hub / sprocket is highly recommended

    Harbor Freight 79cc engine kit ? .... Tell us more ! Sounds like your trying to compare a raw engine to a complete kit.

    Also, are we talking frame mount, or rack mount ? The more you tell us, the better we can help.
     
  17. dotcom

    dotcom Member

    harbor freight 79cc engine with rack mount or frame mount versus an 80cc china kit from ebay
    Which would perform better?
     
  18. V 35

    V 35 Member

    Any motorcycle chain lube will do it. Some riders like 90wt gear oil, drip a few drops on chain after a ride . WD 40 is more of a cleaner than a chain lube, ok for pedal chain, wimpy for powered chain.
     
    dotcom likes this.
  19. Fabian

    Fabian Well-Known Member

    Automatic transmission fluid (ATF) works well as chain lube (in a clean riding environment), plus it has a detergent infused into the oil, making it easier to clean the chain by simply adding a little more ATF on the chain.

    For more serious riding in a dirty environment, i mix 30% Molybdenum Disulfide grease in with 20% ATF and 50% Mineral Turpentine. Mix it all together in a bottle and shake vigorously till the grease has dissolved into the ATF and Turps.
    Apply this mixture to the chain and hand crank the pedals so the lube nicely covers the rollers and soaks into the pins. By the morning the turps will have evaporated, leaving a good coating of grease and oil on the internal surfaces of the chain as well as the outside of the chain rollers.
    This method prevents lube flying off the chain; keeping the lube where it should be, and it keeps the bike frame a lot cleaner. The downside is that when dust mixes with the grease, it forms a filthy black paste that is horrible to try and clean; not only just the chain but your hands and fingers; getting under your finger nails, staining them black for the next 3 weeks.
     
    Last edited: Feb 19, 2014
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