loss of power going up hills

Discussion in '2-Stroke Engines' started by blade381, Sep 27, 2007.

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  1. blade381

    blade381 Guest

    Hi I have a new 70cc motor only have used 2 gallons of gas when I first got the thing it would clime hills easly now it slows down when I clime changed both gaskets the muffler and carb ones that helped but still not like it was before. looked at some posts on here but cant same to find any answers I dont see any loose screws ether anyone got any Idears and can bad sparkpluge have something to do with it but if the plug were bad would it just not start. also I was using 16:1 mix and now I am using 24:1mix Im thinking maybe go up two 35:1 or even 40:1.

  2. When you're moving before you get on that hill,switch to the highest gear your bike has assuming you have a multi geared bike and pedal like your mama depends on it.
    These engines need to keep singing to be happy,and on hills you have to help it on it's way.
  3. check to see if your clutch is slipping - that started happening to me due to my riding style (I wasn't pedal-starting from a stop) and clutch was wearing out and slipping under high strain.
  4. kevbo

    kevbo Guest

    Other possibilities:

    Vacuum leak: A lean mixture will cause more trouble when you are asking the engine to make more torque. Variable venturi carbs tend to go lean when you open the throttle too wide at too low an rpm. This is commonly known as "bogging".

    Fouled plug: When you open the throttle, you allow more air into the engine. That extra air gets compressed to higher pressure. Stuffing more air molicules between the spark plug electrodes requires more voltage to start an arc. If the plug is dirty, the electrons might find it easier to pass through the carbon and crud build-up on the insulator than to hop through that high pressure fuel/air mixture. Translation: Fouled plugs start to cause trouble at WFO before they cause idle issues.

    Fuel restriction: Check the screen on your fuel petcock for crud.
  5. japat100

    japat100 Guest

    i take it that you already checked your head bolts ,and head gasket ...

    gas too rich,
    low compression ,
    too much back pressure on muffler

    loss of power ..-----------------------
    just somethings to look for
  6. gauge

    gauge Guest

    i noticed the same thing and then 10 miles l8r cracked piston, good luck japat
  7. blade381

    blade381 Guest

    I cleaned the plug that seems to help but my clutch cable broke! before I had A chance to realy test it on the big hills theres all ways somthing with this engines LOL I feel sorry for anyone who got one of these things for real tranportation you have to check every thing all most every time you ride. still very fun thu
  8. ibeenjammin

    ibeenjammin Guest

    Hey blade-

    I have a couple of posts in here about the same problem. I have tried almost everything. A friend of mine just recently purchased a used 70cc motor with almost every gasket blown. Bear with me on this one, hopefully it will make sense. I made all new gaskets for his motor and just swapped out the motor on my bike with his. I tested the compression on his motor, it was roughly the same as mine, right around 115 psi. Here is the kicker....his motor (just the engine block) was connected to my carb, cdi, exhaust, fuel tank, throttle, you get the idea. His motor on my bike has the power my motor once had. Oh yeah, it climbed hills like a champ like my motor used to do. How do we explain this..... I do not have the slightest clue. My gaskets are good on my old motor, I was thinking that maybe I need new rings, piston, and cylinder. I can't imagine that would be my problem though because my compression rating is right around 115 psi. I was told that anything over 90 psi is good. I feel your pain and if I figure it out I will send you an update. If you figure it out, please send me an update. Hope this helps. I am still confused.
  9. blade381

    blade381 Guest

    I give up trying to figure it out and just pedal a littal On the realy big hills but lately it seems to be having more power maybe the the gas line or carb was or is cloged and by running it will on clog it self but I realy dont what to take anything apart again unless I have too. Im going 26mph on the flats with a 50 tooth sprocket fast anough for me.
  10. JemmaUK

    JemmaUK Guest

    If its not a fuelling problem, an ignition problem or a exhaust problem could it be to do with the valves on the engine? a compression test wouldnt necessarily show up a problem with the valves - and considering you have changed just the one thing - ie the mechanical part of the engine - ignition, exhaust and fuel are the same - as you say its unlikely to be a cylinder/piston problem because the compression is well above minimum - so about the only thing left is some sort of problem with the valves - maybe carbon build-up or they are tired?

    The only other suggestion I have is to break down your engine and re-gasket it then put it back on the machine to see whether that makes a difference...

    just a thought..

    Jemma xx
  11. srdavo

    srdavo Active Member

    note: The "Happytime" 2 strokes do NOT have valves.
  12. My engine was starting to lose some power too lately so I took off the muffler and was about to do that Dax modification with a hacksaw but I couldn't get the cap off. So I let things go but I did notice a buildup of carbon on the muffler pipe that goes in the cylinder. So I scraped it off and tightened it back down. Then i proceeded to check all the other nuts. The head bolts was a little loose about 1/8 of a turn it tightened down without I would say maybe 60 poot pounds of torque according to my mental torque gauge in my brain and the intake nuts needed about a half a turn. Then I took it around the block and my power came back.
    Maybe this winter I'll change out all the gaskets,clean it up some,and try to figure out how to take that muffler cap off.
  13. Simonator

    Simonator Guest

    60 ft lbs ?! The owners manual that came with my happy time 2 stroke said 15 ft lbs for the head nuts.
  14. Woah. I didn't give it my all...it's snug.

    ...I better git me a torque wrench.
    It was..it turned an 1/8 of a turn without much effort....
    ......yea...torque wrench.
    Thank God nothing went "craaack"
    Naw. I'm thinking back in the auto days when standard lug nut torque is 95 ft pounds...then thinking 60 ft pounds is fairly light.
    I'm pretty certain I didn't overdo it.
    Last edited by a moderator: Oct 19, 2007
  15. Simonator

    Simonator Guest

    Hehe... I doubt that just giving it a snug is 60 ft lbs. I know what 60 ft lbs feels like. You would have to put that engine in a vice to keep it still in ordr to torque to 60 :)