Engine shuts off after short time running

Discussion in '2-Stroke Engines' started by noahindisguise, Jul 25, 2010.

  1. noahindisguise

    noahindisguise New Member

    Hey guys, I run a 49cc engine on a cruiser frame. I'm using pennzoil 2 stroke oil 32:1. I had a fouling problem with the spark plug the other week but when I changed the gap it turned out to be fine. The gap was set around .20-.22 and it was very powerful. When I would pull the clutch in coming to a stop the engine would rev very high and I'm not sure why, it sounded like it was going to explode lol. I just changed the fuel filter and drained the carb too. When riding the engine was very hot and wouldn't start up after about 15 minutes of riding. At idle it stutters and it didn't previously. I'm unsure what the problem is because when I got the bike it was running perfectly. I keep thinking it's the oil/fuel ratio but I'm unsure. I'm new to the 2 stroke engine and any help would be much appreciated. Thanks
     

  2. AussieSteve

    AussieSteve Active Member

    Sounds a little to me like a lean fuel/air mixture.
    Double-check for air leaks at the intake, either where it mounts to the barrel or where it fits the carb.
     
  3. machiasmort

    machiasmort Active Member

    I agree w/aussie, but also make sure that the needle is set up correctly on the end of the throtle cable. The directions included w/these kits can be misleading and cause the needle to free-float when the throttle is released if not properly set up.
     
  4. machiasmort

    machiasmort Active Member

    Look at these real close!!! It took me a few times because the directions were screwy! This will help a lot of people if somebody could convert it!

    Right now, I've got everything in Word format and the file is too big to post here. PM me your e-mail address.

    One of the mods who know more about file conversion should e-mail me also.

    I've got a great carb tutorial if you guy's could figure out how to resize it!
     

    Attached Files:

  5. noahindisguise

    noahindisguise New Member

    Ah, the air filter needs changing. Looks like the rubber on it has been eaten away. Where could I find a replacement filter? Would any auto parts store have them or should I find a motorcycle store?
     
  6. AussieSteve

    AussieSteve Active Member

    Most HT kit suppliers should be able to sell you an air filter. That won't be causing your problem, though. It'll be on the secondary side of the carb, if it's caused by an air leak.
     
  7. machiasmort

    machiasmort Active Member

    problem is not the filter, agreed!

    check your carb slide, needle assembly

    Here's the third part with my last above post, can't believe I got it to work.
     

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  8. noahindisguise

    noahindisguise New Member

    Air Filter

    Hey guys, I was wondering where I could find an air filter for my chinese 49cc engine? I'm not sure what mm it is, but it looks like a simple part to find. Also, are there any type of performance filters out there?
     
  9. a/c man

    a/c man Member

  10. noahindisguise

    noahindisguise New Member

    high rev when clutch in

    Hey guys, I recently put a new fuel filter on, a small one from advance auto parts and my previous one was a car sized filter. Now, when I come to a stop and put the clutch in, the engine revs crazily high and it sounds like the whole engine will explode. I'm unsure if this is because of the new filter or what. Any help is appreciated.
     
  11. noahindisguise

    noahindisguise New Member

    carb part

    Hey all, there is this rubberized piece that goes in the carburetor that is supposed to make it tight, but after awhile of riding it still kicks back the carb and I lose a little power. I have to constantly keep moving it up from coming off. Do you guys know of a replacement piece of rubber material I can put there so it will stay put?
     
  12. AussieSteve

    AussieSteve Active Member

    What type of engine and carb?
     
  13. motorpsycho

    motorpsycho Active Member

    it sounds like you have an air leak...maybe at the intake manifold. This would have nothing to do with replacing the fuel filter.
    or, your slide inside the carb is sticking, throttle cable possibly binding and holding the slide wide open.
     
  14. motorpsycho

    motorpsycho Active Member

    check e-bay for pocket bike, mini chopper, moped high flow air filters.
    you can get a high flow k&n style filter for around $10.00 $15.00 + shipping that will go right onto your carb. they come with a velocity stack that is held to the carb with 2 screws, and the filter clamps around the stack.
    i put one on mine and it made a SLIGHT difference, but it sure looks better than the stock air filter housing. this one comes with the stack, mounting screws and even a new choke plate assembly.

    http://cgi.ebay.com/ebaymotors/Mini...temZ180353849875QQptZLHQ5fDefaultDomainQ5f100

    here's one that already has the choke mounted to the stack. you would have to remove the choke plate and lever from your carb, and just bolt this stack onto the back of your carb.

    http://cgi.ebay.com/33cc-43cc-49cc-...tem&pt=LH_DefaultDomain_0&hash=item2556b36195
     
  15. AussieSteve

    AussieSteve Active Member

    I agree with motorpsycho, it sounds like an air leak causing a lean mixture.

    If the new fuel filter restricts flow it could lean out the mixture and cause a similar condition, but that's not likely. These engines don't need much flow. I use the one below without problems.
     

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    Last edited: Aug 3, 2010
  16. noahindisguise

    noahindisguise New Member

    It's a chinese model, I'm not sure the exact number etc. I bought it off of someone who had built it up.
     
  17. AussieSteve

    AussieSteve Active Member

    A pic would help, then. I can't picture exactly what piece of rubber you're talking about.
     
  18. GearNut

    GearNut Active Member

    I think that he is talking about the o-ring trick.
    It is a common belief that putting an o-ring inside the carburetor spigot before installing it on the manifold will prevent an intake leak at that connection.
    The only way it will work is if you push the carburetor very hard against the manifold and hold it that way as the mounting clamp is tightened.
    If the o-ring is not made of the correct rubber (Buna-N) it will swell and soften to the point where it no longer fits in the gap where it lives and can easily get sucked into the engine. There are square section o-rings sold to do the same job, but the same warning applies. The best way to o-ring a manifold connection is to have a groove just at the very end of the manifold that the o-ring will fit into, like a Manic Mechanic manifold.
     
  19. AussieSteve

    AussieSteve Active Member

    I agree, Gearnut, that the usual way of fitting an 'O' ring isn't reliable. I did as you say - filed a groove and fitted an 'O' ring to an after-market alloy inlet tube. (A fuel-resistant 'O' ring.) Works well. No more leaks ever.

    More info in NT carby/inlet leaks - a reliable solution
     

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    Last edited: Aug 4, 2010
  20. machiasmort

    machiasmort Active Member

    I still say check the dang carb assembly, but first the seal between carb and jug intake.

    CHECK THE CARB ASSEMBLY!
     
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