No power when clutch is engaged

Discussion in 'Motorized Mountain Bikes and Road Bikes' started by seanbbolson7878, Aug 21, 2019.

  1. seanbbolson7878

    seanbbolson7878 New Member

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    I'm new to this I bought a kit on eBay for 100 dollars and I have it on my bike and it revs up fine but when I try to ride it down the road it can't make it up a super tiny hill and it starts jerking bad. If I pick up the back wheel and disengage the clutch it revs up and then bogs down to like mid throttle. And its brand new like not even an hour on it and i took the head off and the cylinder has some scores near the exhaust Help!

    26 inch giant revel 3
    "80cc" kit from eBay
    All stock
    Running 20 to 1 1566416001974350552194.jpg
     

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  2. allen standley

    allen standley Well-Known Member

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    Welcome to the forum!
    What's your fuel / oil ratio?
    i took the head off and the cylinder has some scores near the exhaust Help!
    Uh Oh.... Can you show a pic of the cyl. Some of the New bargain priced kits are coming through with the cylinder Plating flaked off. That does cause the power deficiency as you describe. Follow this search hopefully it's helpful.
    https://motorbicycling.com/search/20992888/?q=new+engine+no+power&o=date&c[title_only]=1
     
  3. seanbbolson7878

    seanbbolson7878 New Member

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    It's not scored bad but it's got some scores on the exhaust side
     

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  4. allen standley

    allen standley Well-Known Member

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    That's not scoring...Looks like yet another bad plating job by China. Too bad we can't see deeper down. If it looks like that where the rings travel I would replace that cyl.
     
  5. seanbbolson7878

    seanbbolson7878 New Member

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    I'm running 20:1 for oil
     
  6. seanbbolson7878

    seanbbolson7878 New Member

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    I put a smaller main jet in the carb because it was 4 stroking under load I haven't tested it out yet though but I hope it works
     
  7. allen standley

    allen standley Well-Known Member

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    Go 32:1 4oz oil 1 gal gas.
     
  8. allen standley

    allen standley Well-Known Member

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    Smaller main jet is only good for 4 stroking @ 3/4 throttle to full. Did you try raising the clip position so as to allow the needle to set deeper in the carb? None the less - I fear you need a new cylinder.
     
  9. seanbbolson7878

    seanbbolson7878 New Member

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    Yes I tried all the options on the needle I think I'm going to buy a cylinder next thank you
     
  10. allen standley

    allen standley Well-Known Member

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    You'll get it. Good Luck to you.
     
  11. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The first thing that came to my mind when you said "it starts jerking really bad" is that you might be riding it too slow!! First of all, these things run kinda bad until they are fully warmed up, & you also have to ride it fast enough that the engine is in it's RPM 'power band'... (meaning that it's gutless while going too slow).

    Switch to 32:1 mix (4-oz oil per 1-gallon of gas)

    The cylinder might still be good to use... Put the head back on & torque it down to 12 ft/lbs (if you torque it too much, you'll bend the head & cause a compression leak.


    Another thing... PUT THE STOCK JET BACK IN IT!!! You don't want to re-jet it until it's fully broken in!
     
  12. seanbbolson7878

    seanbbolson7878 New Member

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    Yea I'm trying to ride it in powerband but it doesn't get there when it's under load. When I give it gas it just starts to 4 stroke. It revs up really good with no load but bad with load, and I'm only 140 pounds so my weight wouldn't really matter
    I'll try to send a video later in the day or tomorrow
     
  13. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Here's a crazy question... Is your choke lever up or down???
     
  14. seanbbolson7878

    seanbbolson7878 New Member

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    It's all the way down if it's up it barley revs
     
  15. Capnspaldin

    Capnspaldin New Member

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    Is that intake able to suck air? I can't tell by the pic but it looks like it might need to be offset?
     
  16. xXNightRiderXx

    xXNightRiderXx Active Member

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    You will need to get an offset intake. I had a roadmaster frame that was shaped exactly like that Giant. And always, ALWAYS, run in the engine at or higher than the manufacturers suggested ratio before doing any modifications or running it at full speed. Not doing 20 miles at half speed could result in poor performance and excessive wear. Plus, I don't buy engines from China anymore, not since the tariffs. They seem to be deliberately botching products coming to the US after all that. Many of the things I recently purchased from China have been of very poor quality, such that I personally would throw them out before selling them, plus they take forever to ship and arrive.
     
    allen standley likes this.
  17. allen standley

    allen standley Well-Known Member

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    I see this too...
    I don't buy engines from China anymore, not since the tariffs. They seem to be deliberately botching products coming to the US after all that. Many of the things I recently purchased from China have been of very poor quality, such that I personally would throw them out before selling them, plus they take forever to ship and arrive.
     
  18. allen standley

    allen standley Well-Known Member

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  19. xXNightRiderXx

    xXNightRiderXx Active Member

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    I wish I did, but at the same time, I'm done with building two strokers. Last two engines I had just kept failing and I needed something reliable, which led to my 79cc 8 speed shifter. But that's another thread altogether.

    As far as the cylinder goes, I believe zeda sells jugs. That may be all you would need to get that engine goin again, aside from the offset intake.
     
  20. Jimmy Bloodmaker

    Jimmy Bloodmaker Active Member

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    way to lean, need a bigger jet. i use some of the cheapest kits there are. just gotta run 'em rich like a chain saw. if it revs great and doesn't limit out and sputter a bit with no load at full throttle, you're gonna burn your engine up. it's running lean. a two stroke should always be running rich with no load. it's when load is applied tht extra gas gets used up or to cool the cylinder.
     

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