i think my "80cc" has issues. top speed only 28mph with shifter kit...

Discussion in 'Motorized Bicycle General Discussion' started by jerseykat1, Oct 12, 2008.

  1. jerseykat1

    jerseykat1 New Member

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    plug wire is new. i may actually be running too rich. it runs best in the highest c clip position.
     
  2. jerseykat1

    jerseykat1 New Member

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    i have had no luck so far. does anyone sell pre tuned carbs?
     
  3. velardejose

    velardejose New Member

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    Hi
    Have you checked the screen filter inside the tank?
    Peace
     
  4. jerseykat1

    jerseykat1 New Member

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    no but as soon as i finish eating i will. thank you velardejose.
     
  5. jerseykat1

    jerseykat1 New Member

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    removed that screen in the gas tank and no change (i have a fuel filter). i made my carb jet a little bigger and still no change. i am starting to think i just have a bad motor. seriously considering the purchase of a new one.
     
  6. Goat Herder

    Goat Herder Gutter Rider

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    Spark gap too small for my tast I use Directhits from pulstar Its a step up transformer not alot of gain , but I will always use one.These ch really need to breath what kind of air filter are you using me 4000 miles with pantie hose 3 or 4 layers hope that helps. I'am the fasted kid on the block still ,and on the same ch . Good luck my man
     
  7. jerseykat1

    jerseykat1 New Member

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    i am using the stock air filter. with the cover removed and the black filter thing bolted directly to the front of the carb for more clearnce, i just shortened the screws.
    i tried many diffrent gaps .020"-.028" and nothing changed. what is directhits from pulstar? are you talking about ignition modules? i read your other post and i think i could possibly have a bad CDI is directhits an upgrade replacement or something to add in addition to the factory CDI?
     
  8. Saddletramp1200

    Saddletramp1200 Custom MB Buiilder

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    Hey, You are not and should never run a brand new motor full out for a least 200 miles. The rings need to seat to the cylinder wall. If you have "glazed" the cylinder walls you loose compression and it will never get better. Varry your speed, don't go full throttle for at least a gallon or more and It will mos likely be fine.
     
  9. jerseykat1

    jerseykat1 New Member

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    i agree with you, and i have been taking it fairly easy on the motor (prior to me purchasing the shift kit i would cruise at around 18-20mph but i wanted to see what it could do with some gears only one or 2 times), but even if the walls were glazed and it had lower compression as a result, there still isn't a reason for the engine to not rev past what i think is about 3500-4k rpm without any load if compression was lower than normal it would just be low on power and or misfire but it has quite a bit of power up to about 3-4k rpm where it hits that invisible wall. In fact it will rev high maybe to 5k at most then bog down to about 3-3.5k rpm with WOT. If i feather the throttle i can slowly get it up to about 5k rpm and maybe stay there but anything past 3/4 throttle and it bogs down to the 3k range (note i am only guessing the RPM based on sound).

    feels like a car with a rev limiter.
     
    #29 jerseykat1, Oct 14, 2008
    Last edited: Oct 14, 2008
  10. Wheel Rush

    Wheel Rush New Member

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    You haven't mentioned the carb float yet have you given it a good once over ?
     
  11. jerseykat1

    jerseykat1 New Member

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    i overhauled the carb, took it apart as per normans guide cleaned it out, enlarged the jet one size up, and slapped it back on with the same results. one of my clients just purchased a "80cc" kit from me so i ordered 2 kits (yes i resell BGF kits locally for a profit) one for me one for him. When it comes i will be swapping parts around to see what my problem is plus i have another bike that i need to put together for a different client so it should work out well. only problem is i have to wait 4 days for it to ship from Cali. wish there was reasonably priced sellers on the east coast. anyone want to express mail me a CDI?

    i even modified my intake manifold to add a valve that will allow me to lean it out little by little (fuel petcock) it does give me more low end power when i adjust it, however i still hit that invisible rev limiter when i try to go WOT and cant get past 20mph in 7th gear. I have experience fixing cars and the syptoms that i am getting is typical of fuel starvation (clogged filter, bad gas, feul pump, etc) however there are very rare occasions that i had to replace an ignition coil pack to cure that problem. But the cars i have experience fixing were all fuel injected ford/linc/mercury. none of which are 2 stroke (not that there is a 2 stroke car but you know what i mean), but i am guessing the same principles apply. I do know for a fact as goat herder pointed out in another thread that ignition systems will fail under load i have seen this MANY times on fords and other vehicles.

    not experienced with magneto setups, is it possible it could be the magneto on the left side of the engine?
     
    #31 jerseykat1, Oct 14, 2008
    Last edited: Oct 14, 2008
  12. Norman

    Norman LORD VADER Moderator
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    stock main jet is around 0.070 mm My engines run the best on 0.065mm main jets.
    check your needle for taper I think it should start out by the clip grooves at 0.070 and taper down to 0.065 those numbers might not be right but if you can mic your needle it needs to have a taper. Pablo had one that didn't have the proper taper and it would not rev up at all I worked on it and got it to working good on my bike then I shipped it back to him I guess he either shelved it or put it on his bike.
    If you want I can have you send me your carb and I'll test it on my bike and see if i can do some mods to get it to perform all you need to do is pay for the shipping. I have 70cc and the cough, cough, 80cc engines to test it on.
    Norman
     
  13. jerseykat1

    jerseykat1 New Member

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    Thank you norman for extending your servies, i really appreciate it. But i am happy and ashamed to announce that i have solved the problem. It was a simple and stupid mistake on my part. when i installed the shift kit (by the way this thing makes my bike a freakin rocket havnt recorded top speed yet as its too dark out right now and i cant see the speedo but it flies now) my engine had to be slightly relocated and such forced me to remove the filter housing, shorten the screws that secured it, and bolt that honey combed shaped thing directly on top of the crappy little foam tpype filter. well that put it too close to the intake port and i guess at higher rpm it was just not getting enough air because of how close the foam was to the opening (i feel like an idiot goat herder hit the nail on the head when he said "these ch engines really need to breath"). So to remedy this i used some nylon front door screen (yes the kind used to keep bugs out your house) folded over about 4 times, used my Dremel to remove the plastic sections that are directly over the carb port, and installed it in the same manner. Problem solved and it should provide about the same filtration as that crappy foam filter. maybe i will play around with difrent materials tomorrow. below is a picture of the carb with mt revised "fit in a tight spot filter" the valve sticking out of the intake manifold is something i created to try and adjust A/F ratio it works well i will try and fine tune it tomorrow. Can't wait!!
    [​IMG]
    [​IMG]
     
    #33 jerseykat1, Oct 14, 2008
    Last edited: Oct 14, 2008
  14. Ghost0

    Ghost0 New Member

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    I would try maybe turning your intake manifold upside down, I have seen it done before. Or I think Norm can make you a custom one. It should get you your clearance back for your air filter, might even have enough then to put on a good one. ;-)
     
  15. jerseykat1

    jerseykat1 New Member

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    i am afraid it wont flow right if i turn it upside down. if you look in the background you will see two pieces of metal leaning on the step ladder, thats what i planned to use for my custom intake but i decided to just eliminate the plastic cover. i may still fabricate a custom intake in the future when and if i decide to port this motor.might end up being a winter project, port the motor, with custom matching intake, and a custom tuned expansion pipe for the exhaust. should be able to hit at least 40mph after that.
     
  16. Goat Herder

    Goat Herder Gutter Rider

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    (^)I used panty hose in a pinch when I was fooling with mine in the begening, its still on there. Had frame clearance issues. Good to see you finally woke her up
     
  17. jerseykat1

    jerseykat1 New Member

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    i am thinking of using the material in those masks that you put over your mouth when your painting, or working in dusty areas, i think they flow pretty good and provide good filtration, gonna try a few options tomorrow including the original foam filter which should flow pretty well now that i removed the lower half of that baffle thing, as crappy as the foam filter is i think it may provide the best flow and good filtration. we will see tomorrow.
     
  18. velardejose

    velardejose New Member

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    Congrats!
    Now its time to enjoy your mb (^)
     
  19. OSCAR383

    OSCAR383 New Member

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    I FORGOT TO TICHTEN THE SCREWS ON MY AIR CLEANER WHEN I FIRST GOT IT AND IT FELL OFF ON THE ROAD . I RAN WITH NO AIR FILTER FOR ABOUT 250 MILES BEFORE I ORDERED A NEW ONE THEY DO RUN BETTER WITH OUT ONE :oops:
     
  20. jerseykat1

    jerseykat1 New Member

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    pantyhose!!!! works great goat herder. yes there is a noticeable difference when you ride with no air filter, i think i am going to port this sucker out and try to find a carb with a bigger port.
    thank you guys for the help.
     

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