Dax 70 cc motor diagram?

Discussion in 'Frame Mounted Engines' started by Keepthedrivetommy, Oct 2, 2007.

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  1. Hi all,
    I have been having a problem like the thread : http://motoredbikes.com/showthread.php?t=6239&highlight=power+loss but I am having this clicking noise, sounds more similar to a metal blade ceiling fan spinning very fast, and then someone taking a metal stick and pushing the metal stick into the spinning blades (imagine really fast loud metal clicking) It was doing this when I get up to 29.5 mph and over, but only when I let off the throttle. But I could speed all the way up to 33 before the engine sounded like its rpms were getting too high. Now, I get up to 31.2, and the rpms get real loud and all of a sudden the motor loses power, like someone yanking off my spark plug conector. I saw this thread from Ducky and he was basically having the same problem as me, only i am having a loss of power at the high end. SO I want to open the motor up and check that wrist pin thing, and the piston ofcourse, but I dont know how to open the motor up, from which side, and am afraid that if I open it up, something might fall out and I wont know where it goes. Does anyone have a diagram or instructions on how to open the motor up and where everything is?

  2. hot70cc

    hot70cc Guest

    Take the 4 Nuts off the top of the engine and it will all come off (HEAD&CYLINDER), The piston will slide right out of the cylinder. No Need To worry If you just want to check the piston /cylinder/rings/needle bearings/wrist pin. Thats all you need to do. Hope that helps.
  3. gauge

    gauge Guest

    remember u have to compress the rigns when reinstaiing
  4. i opened the top part up but all there is, is a hole where the cylinder im guessing its the cylinder, and the piston but there isnt anything esle to take apart. How do you take the piston out?
  5. gauge

    gauge Guest

    how many miles on that dax 70 mine blew at 186 miles
  6. several hundred. Probably close to 500. Ive been ridding it hard since the mid/early summer. What happened to urs?
  7. mickey

    mickey Guest

    Pull up on the cylinder and it will slide up the studs and off. The piston will slip out the bottom.
  8. gauge

    gauge Guest

    i was pulling at 15 mph easy then tap tap tap just died and pulled th intake manifold off to discover a hole, then i looked further to find it was a big crak
  9. Bertsimon

    Bertsimon Guest

    Maybe this will help you out

    Attached Files:

  10. This is getting a little confusing. I am checking underneath the piston, right? But once I unscrew the top 4 nuts and slide the "cylinder" off the screws, the piston is sitting in the hole, and I cant just grab it and pull it out because there is noting to grab on to.

  11. azbill

    azbill Active Member

    slide the cylinder all the way off and it will reveal the piston/rings in all their glory
    if you are uncomfortable doing this, perhaps you could take it to a small engine shop and have them do it, they may let you watch, so the next time you could do it yourself
    hope that helps :)
  12. mickey

    mickey Guest

    The head is the part on top. You removed that or else you could see the hole (bore of the cylinder) then you slid the cylinder off (the rest of the part above the crankcase with fins). If the piston is too low, use a wrench to rotate the sprocket to move the crank that the piston is attached to. The piston will rise up (just like it does in the cylinder) and you will be able to grab it, wiggle it around, kind of inspect under it (not a lot of room, perhaps a small mirror would help). If worse comes to worse, you remove the clips holding the wristpin in place and press it out, freeing the piston completely.
  13. this is what I got so far. I unscrew the top 4 nuts, and the top part comes off, but I cant grab the piston. I was able to move the piston up, but it moves right back down before it reaches out of the hole. I dont know if there is more to take off, like the rest of the motor casing with all those fins. What do i do from here?

    Attached Files:

  14. mickey

    mickey Guest

    Yes, remove the exhaust pipe, then remove the cylinder.
  15. mickey

    mickey Guest

    Also remove the carburetor.
  16. srdavo

    srdavo Active Member

    I agree with azkronic. take it to a small engine/lawn mower shop. in the past, I have taken things apart that NEVER went back together.

    fyi....you can check your wrist pin without removing the piston from the cylinder. thank augie for that tip. best of luck to ya.
  17. finally, I got the rest off. I decided to take a look at my magneto, just incase, and it doesnt look so good, but maybe it wont make a difference. Before I took all this apart, I took it out for another ride, and things have gotten worse. Now, I am losing power once I get up to 26 mph, and cant really accelerate without the engine losing a lot of power. Then I let off the throttle for a second or two, and then accelerate again, but it loses power again. This is gettin bad. Where do I go from here, under the piston, right? How do I take the piston off?

    Attached Files:

  18. mickey

    mickey Guest

    Now that is starting to sound like it might be a fuel supply problem (or an oiling problem). On a 4 stroke, I'd reach down an shoot a shot of ether in to see if the motor sped up but I'm sure that would be bad for a 2 stroke. How about pressing the primer bulb down during the stumble to push the float down and let more fuel in. (I'm trying to think of some way to, for sure, push extra fuel down the throat). Could you work your speed up by accelerating, rolling off a little, accelerating again, rolling off a little, etc? Or was there just a max RPM that the motor would refuse to exceed?
  19. its more of a max rpm that my engine wont exceed, which stops me from getting above 27 or so. If I dont let off the throttle for long enough, then the motor stays in that state of power loss. I was thinking that it had to be something with the carb or feeding gas into the motor because that is the most logical thing, if the motor wont go faster, it is because it needs more fuel, thus something must be restricting it, but I dont know how to check for that.

    A lot of people say that they open up their carbs and clean them out, but I again, dont know how to open it up without messing something up.

    Also, I have noticed that there seems to always be a constant film of gas mixture covering the underside of my carb, motor, and the entire area around my fuel tank cap. Also, the carb just seems to be covered in the mixture completely. I clean it off, and ride it, the next day, everything seems to be covered again. Not a terrible amount, just greasy. Is this normal?
  20. taking out the wrist pin

    I had to put this all aside for a while because school was getting pretty hectic, but Im back. i LOOKED inside the hole on the side of the piston, im guessing that's the wristpin connection rod, or something with the wrist pin, and I noticed that there was a slight dark line circling the inside of this hole. I think that it looks like a crack. So now, all I need to know is how to take out the wrist pin, or take off the piston, so I can see if anything really is broken and replace it, then I can be on my happy way. The other thing that I noticed was that the piston actually wobbles around a lot. I can jiggle it side to side, or up and down a little. Its not very stable.