engine not running right. Possibly leaning out

Discussion in '2-Stroke Engines' started by Simonator, Apr 17, 2008.

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  1. Simonator

    Simonator Guest

    My engine was running great until one day. I was out riding in the rain, and the engine died. It would not start back up or fire at all. I tried it again a few days later with no luck. The engine was getting fuel, spark, and compression. Clutch was not slipping either. I found a spare coil layin around, so i swapped that one on. It fired right up. I was like WEEEEEEEEEE! Until I hit about 20 mph (where the powerband usually starts). It started sputtering and would not go any faster. It also sputters under a load. It is not acting like it has an air leak. It idles down real fast when i disengage the clutch. It runs worse when I play with the choke. Before when i had an air leak, it ran good with the choke half open. It doesnt even like to start with teh choke. It fires right up with the choke off..... weird... I checked the spark plug. It is a light tan color and dry. The carb was adjusted the 3rd spot down on the pin. I went to the 4th (richest) setting. It ran worse. I pulled the plug right after that, and it was still the same.
    I bought a multimeter so I can test the magneto. I just haven't figured out how to use it. Can someone explain this to me, or link me to a thread that explains it?
    I also checked the compression. I did it when the engine was cold. It is at 70 psi. Seems a little low, but maybe it is because the engine is cold? Even if it is a little low, the engine should still run ok. I would like to check it again when the engien is warm, but I do not have the gauge handy.

    Any ideas?

  2. BSA

    BSA Guest

    Very odd, try running on the second slot. Can you give us a rough idea of how high you are above sea level. I think that you may be running to rich, if you were too lean the choke would improve the situation no make it worse. Try the second slot on the needle, and if that doesn't work try the 1st slot. A good way to test if you are running two lean is to wait for the engine to warm up and then engage full choke; it should kill the engine instantly.

  3. Simonator

    Simonator Guest

    I am at about 600 feet above sea level.
    I am running the 2nd slot right now. It is Still running the same. Full choke at idle speed never kills the engine instantly. It always takes a few seconds. My carb is O ringed. Before I O ringed it, there was a leak. I sprayed brake cleaner where the carb clamps to the intake. That slowed down the idle. Now if i spray brake cleaner there or around the intake gasket, the idle does not change at all. I don't think there is an air leak. I am at about 600 feet above sea level.
  4. Demosthenese

    Demosthenese Guest

    could be your electrics somehow. I know that just replacing the wire and plug socket that comes out of my cdi, my bike works WAY better now. If you're getting spark it could still be a poor connection leading to a weak spark, or you're cdi could be damaged or something. You said you replaced the coil; what did you mean?
  5. Simonator

    Simonator Guest

    I just ran my finger on the muffler outlet. It is a little moist. Does that automatically mean I am rich? Or is this normal for a 2 stroke?
  6. Simonator

    Simonator Guest

    I used my spare CDI from my last motor.
  7. sparky

    sparky Active Member

    I think this is my problem... my plug wire looks terrible & I've only been running this thing for a month, not even everyday.
  8. Simonator

    Simonator Guest

    I think i figured out the problem. I finally removed the magneto cover and looked inside. It turns out that there is some trapped water in there. Time to let it dry out and see what happens. I'm going to order a new magneto just in case this doesn't work. Why did I wait so long to remove the magneto cover?! DEE DEE DEE!
  9. Simonator

    Simonator Guest

    Well the magneto tested good.

    I just came up with another idea. When I couldnt get it to run, I removed the head, not knowing that those studs and nuts hold the whole cylinder on. maybe I broke the seal on the gasket at the bottom of the cylinder? If so maybe it is leaking the compressed air/fuel which is causing it to sputter when Im going more than 1/4 throttle?
  10. Demosthenese

    Demosthenese Guest

    the gasket is a metal one, so it can't be torn, i think the head bolts are just supposed to be torqued down to form the seal. I know that i've removed my head and i just put everything back and retightened the bolts and it works fine.
  11. Simonator

    Simonator Guest

    Well, I do know for a fact that it is leaking. My brother has my torque wrench, so I can't torque them until I get it back. Hopefully the head is not warped. I might buy a new head and gasket just incase. I'm sick of this dam thing not running right.
  12. will_start

    will_start Member

    plug ? boogers and gaskets

    I feel ya pain, but the eventual joy/happiness/ride once you work out
    the sweet spot, its all worthwhile.

    I been thinking about your case Sim, one question I've not asked.

    When was the last time you checked the petrol petcock filter (the valve on the P tank), for tank boogers ??
    Also Have you upgraded the spark plug yet ?
    You were saying you had the standard plug.

    I just wanted to say that term.
    Tater was the first I knew to call it that.

    I found that when I did that and the carbie cleanout,
    it would make the motor fire.

    I changed from a **** gasket I made, to a new gasket,
    and it fired right up.

    I also bought a can of ether, just to make sure it would start.

    Just some of the things i did. :p

    Hang in there dude.
  13. Simonator

    Simonator Guest

    I haven't messed with any of that yet. It's because I am almost positive the head is warped, and that is the problem. I can actually see a gap between the head and the gasket at one spot.
  14. will_start

    will_start Member

    these are ideas for contemplation:

    I wonder if a thick gasket would fill in the head warp.
    if you had some gasket goo, if you put it on thick,
    would it fill the gaps.

    just an idea.
  15. sparky

    sparky Active Member

    A thicker head gasket would mean less compression, no?
  16. Simonator

    Simonator Guest

    That is true. Not by much though.

    I am going to order a new head for $20
  17. Irish John

    Irish John Guest

    The recent engine kits have all sorts of quality problems that they didn't use to have although they always had plenty to start with. One of these quality fades is definitely the plug lead connection to the plug cap. It is now made of material that can't take the heat for long and it soon perishes and just sort of rots so the spark it pretty weak. This is now happening really quickly where it used to not be a problem even after 3000 miles. The CDI is probably reduced in quality too but as the lead goes first it's hard to tell. The whole kit is now riddled with deliberate quality fade but if you can salvage an old pre 2007 lead and CDI it should work OK. I haven't noticed how the magnetos have been quality faded cos they usually outlast the other stuff but I'll bet my bottom dollar that it's a prime area for corner cutting especially cos it's hidden from view. The cheaper kits don't include the rubber grommet that protects the magneto from water infiltration and you need to plug it with red gasket sealant. Not an easy job to do in a tidy way.

    RATRODER Guest

    Before you buy a new head try lapping it,400 wet or dry WD40 on flat surface. louis
  19. Simonator

    Simonator Guest

    I used Red RTV to make the whole magneto gasket. It's messy, but works.
  20. Rich

    Rich New Member

    i am new to motorized bicycles and have questions. what are the "slots" on the carbeurator?