70cc bogging down at full throttle?

Discussion in '2-Stroke Engines' started by pianoman8t8, Jan 27, 2007.

  1. pianoman8t8

    pianoman8t8 Guest

    I just got a 70cc motor, and so far i've put around 20 miles on it, but it seems to bog down when i give it full throttle. It seems to go fine just below full throttle, but i was wondering if there was a way to adjust it or fix it so it either stoped bogging down or performed better without bogging down at full throttle.

  2. etheric

    etheric Guest

    Ours did too.
    We tried a few different things, with no success.
    We are remounting the engine though, so the new bike will be our test ground for removing that fullthrottle bog.
    We were still running 20:1 though, so on the new ride we'll put in a new plug and a new mixture and see what we can come up with.
    A plug chop will be first in order on the new bike, as going fast will be our goal with the new ride (the AMF was more of just a cool looking tester)
  3. gone_fishin

    gone_fishin Guest

    hi, pianoman8t8, welcome :)

    i think trying to push a full throttle so soon won't give you what you're looking for, search thru our "general discussion" and "technical help" areas to find a whole bunch of good info on break-in theory.
  4. etheric

    etheric Guest

    ^^^I agree with Augi^^^

    I think breaking it in definately takes priority over it bogging while you are doing something that you may not even want to do.

    BTW, ya sneaked in, Welcome.
  5. Steve

    Steve Guest

    My 70 cc would also bog under full throttle until I opened up the idle mixture screw an additional turn. I know, it's supposed to effect the idle, but mine also effects the WOT mixture.
  6. my has been doing the same thing when i go full throtle and its broken in and i run it on 32:1
    i just ordered a 36 tooth sprocket hope this makes it stop boging heard what sounds like miracles from other who got the 36 tooth sprocket
  7. Tom

    Tom Active Member

    Mine would do that, it was a blown intake manifold gasket. I made another one out of a cereal box, put it on and it made a world of difference.
  8. azvinnie

    azvinnie Guest

    hay guys, l just spoke with roland from spookytoothcycles the other day about this same problem, and it fixed it. it only took 2 min. in your carberator there is a pin(long and thin) and it has a black ring, if you look close at it there is 3 postions the black ring will slide on to the pin. 1, 2, and 3 little grooves. mine was at the 1st position and changed it to the 2nd position and my boging went away, here is a pic ,but its best to look at yours........good luck[​IMG]
    sorry about the crappy pics
  9. Guest

    Guest Guest

    If it bogs down, as you found out, it is the mixture.

    As for not going full throttle on a new engine, that is bad advice. You should take every opportunity to exercise the engine's full rpm range to get a proper break in. If you don't put the engine through its paces, you will never develop sufficient cylinder pressure to seal the rings aginst the piston wall. Also, connecting rods stretch at increasing rpms. If you drive slow the rod won't strech and allow surface mating to occur at those locations where the piston goes when it is revving high. What happens is the cylinder ges mated to the cylinder for only a small portion of its intended travel and when you rev higher you actually cause excess wear from the portion of the cylinder that is slightly smaller in diamter than the rest of it-a taper.

    I can go on but too many knucklehead with no engineering degree to back up their knowledge base.
  10. gone_fishin

    gone_fishin Guest

    is that your "educated" way of volunteering to be technical moderator?

    in 5000+ posts, i have yet to see anyone claim to be an authority on these chinese engines, 'specially not MBc staff...that's why we built this forum, you "knucklehead" :p

    too bad you didn't bother learning any manners while you were becoming an obvious expert on engines.

    yup, i admit i took your remark personal, i think you're expecting too much from a bunch of self-avowed novices...your really good info would have been just as useful without the insults, imo :x
  11. azvinnie

    azvinnie Guest

    dont listen to A-holes

    you tell him augidog, l thought we were trying to help, but l guess l'll keep my mouth shut and let them figure it out on there own. as far as engineering l have my mcse, so up yours drewd. we are only trying to help others, and not be an A-hole at the same time, jerk-off.......................don't put others down cause you thing your a genius, which you not.............
  12. gone_fishin

    gone_fishin Guest

    thanks, azvinnie, but let's DO keep trying to help each other, that's what the MBc is all about :)

    i won't violate Private Messaging, but i only posted the above after addressing this with DrewD privately. all i got for my trouble was more insults, so i took my feelings public.

    anyway, he sticks around or he doesn't...we won't let it stop us from keepin' on 8)

    pianoman8t8:check azvinnie's post...i agree you should try different settings on your mixture, that's probably where the problem lies.
  13. uncle_punk13

    uncle_punk13 Guest

    ya' find one in every crowd...
    Ignore it an' maybe it'll stop.
  14. pianoman8t8

    pianoman8t8 Guest

    Yeah, I tried the clip on every slot (there are 4 slots total in the needle on my carb) and realized that the one groove that it came installed on was the best performing. The 2nd from the top groove... but I'm sending out for an upgraded carb from Simpsons this coming Friday. I can't wait to see how much it will improve. ANd i was checking out that Direct Hit spark plug, but I figured it wouldn't fit on my bike due to lack of space, seeing as how the upgraded plug thing is significantly longer than the stock one. I also have a new idea for a chain shifter whatcha-ma-call-it, and since i have my license back, I can work on it more in the shop when i have some time. but anywho..., and when i get that caqrb, I'll let you guys know how she goes. and If anyone gets one of those direct hit spark things, please let us know how it works, if it's worth it and so-on..


  15. My 49cc has been bogging, and I thought my gas had gone bad. I read this thread and thought maby this is the problem. I got the engine warmed up and idling, sprayed a little carb cleaner near the intake manifold, and it started racing then died. This is a shure sign of an intake leak. Made a new gasket, and it runs great.
    Thanks Tom

    btw my wife still thinks I have bad gas :lol:
  16. srdavo

    srdavo Active Member

    hahaha...bad gas!

    that sounds like a good test for intake leaks.
  17. can some post a pic of what the intake manifold gasket is im sure i know what it is just need to see the pic
  18. The intake manifold is the tube that connects the carburator to the rest of the engine. The gasket is between the engine and the manifold.
  19. i changed the setting on the needle i have for settings on mine and it runs better now than ever
    i also found the gasket fixed it with a ceral box for a temp fix ordered a new one

    just wanted to say thanks to for the help :D
  20. srdavo

    srdavo Active Member

    hey dude...the cereal box gasket is the new one!! :D cereal box gaskets are old school shadetree mechanic fixes. just like new!
    glad to hear your bike is running well!!