Engine Trouble will NOT run

Discussion in '2-Stroke Engines' started by joeltrain, Jul 12, 2011.

  1. joeltrain

    joeltrain New Member

    Ive read and tried everything i can find

    special thanks to Mr. Don Grubee

    2010 66cc GT5 POS

    A little backround. This is my second GT5. My first was great except the rear motor mount bolts sheared off leaving the chain to hold motor in place. Lots of vibration. So I decided to buy a new one as gasbike.net had sent me a discount email. 20 days later I was installing on my new Specialized Hard Rock. CNS carburetor NG. Backfire caused head gasket and bottom cylinder gasket to blow. I only realized the head gasket. Head bolts not torqued by factory. I took two off with my fingers. Put Speed carb from old motor on and sealed head, intake and exh. Did not fix lower cyl gasket. Engine very loud. Significantly less power than old motor. Ran for 1 week.

    Bolt holding crank gear (clutch side) worked its way through cover and fell off inside. Tried repair on side of road but chinese hardware failure (flat/phil pan head cover bolts) stripped. Somehow I made it home. The gear must be pressed on or something b/c i rode all the way home with no bolt in it. Repaired that with old parts, and ran for several more weeks.

    Having problems with fuel mixture. Engine seems to run out of gas going up big hills. After boggin it up a hill, engine goes full RPM for 10-15secs and then idle goes up and down drastically then dramatically then annoyingly and then calms down and idles. Sometimes stalls. Internets says go leaner when hot/humid. Order several jets .66,.68,.70.

    While waiting for jets I discover cyl sleeve gasket leak and repair. Engine sounds much better now but mix prob is still bad. Jets do not solve problem. Order .74,.76,.78.

    THEN, Riding home from corner store i reached 28mph. Fastest Ive been. Running pretty good.....


    Tried the following to remedy:
    new cdi
    new performance wire
    new mag coil
    brushed varnish off mag coil
    sanded grounds down to bare metal
    disconnected kill switch
    checked with voltmeter blue to black plug out 1200rpm drill = 49vac
    grounds good
    spark good
    fuel flows from bowl drain well
    plug is wet
    checked magnet against old motor magnet = same
    blew out carb with compressed air ALL orifices clear
    installed o ring @carb intake
    regasketed intake/cyl sleeve
    checked mag install blue=top white=bottom
    checked keyway TDC piston TDC
    installed hi flow tank drain and new fuel filter
    installed .66,.68,.70..72,.74,.76,.78 jets

    NONE of this worked? I have a new NT new old stock carburetor coming from china. If that doesn't work, i don't know what i'm a gonna do. I can't even think of anything else to try.

  2. motorpsycho

    motorpsycho Active Member

    "Having problems with fuel mixture. Engine seems to run out of gas going up big hills. After boggin it up a hill, engine goes full RPM for 10-15secs and then idle goes up and down drastically then dramatically then annoyingly and then calms down and idles. Sometimes stalls. Internets says go leaner when hot/humid. Order several jets .66,.68,.70."

    This could be caused by the float being out of adjustment. the fact that it only does this when going up hills tells me that your float bowl is running out of gas, and the angle of the carb / bike going up hill is not allowing gas to get to the main jet. Another sure fire clue that it's running out of gas is that it goes to full rpm for 10-15 seconds. it does that because it's running out of gas and the air/fuel ratio is becoming very lean before it finally runs out of gas.
    check your float level and make sure that the carb is as level as possible with the bike on a flat surface.
  3. joeltrain

    joeltrain New Member

    That's an excellent thought, one that didn't occur to me. I bought a hi-flow tank drain valve so that should help with flow. I think i saw some post on here for the clearances on the float level. I will check that. But i still gotta get it to run 1st! Thanks!
  4. HeadSmess

    HeadSmess Well-Known Member

    sounds like youve had fun and maybe learnt one or two things. unfortunately the biggest lesson is still to come...anyways.

    psycho has the train of thought going in the right direction with the float height i say...

    so thats that bit. now. prove its actually a carby issue. pull off the carb. pour a few cc of petrol down the hole. try and start it. if it runs it will rev up once then die.

    that will prove if its the carb or not.

    if it isnt the carb... youll be back :)
  5. HeadSmess

    HeadSmess Well-Known Member

    waaaaait...plugs wet?

    just thinking... plugs arent sposed to be wet ;)
  6. joeltrain

    joeltrain New Member

    wet with fuel, should spark burn that off?
  7. motorpsycho

    motorpsycho Active Member

    Ummmm, yes...it's called cumbustion for a reason.
    if the plug is wet at the electrode, then you do not have spark and your engine should not run at all.
    if it's wet around the threads, it may be caused by too much oil in the gas.
    What gas-oil ratio are you mixing it at? You are using 2 stroke oil and not regular motor oil right? (i had to ask).
  8. joeltrain

    joeltrain New Member

    I am running 25:1 on walmart blue supertech oil. I got my new NT carb today. I can get the float any higher than 19mm. Prev post says needs 2b 21mm. The primer pin is in the way. I read the post on NT adjustment but it doesnt really tell you what the jet size is if you buy the carb separately from ebay shipped from someone in china..lol.

    I also bought a nice new two electrode shorty spark plug today. I looked all around locally and couldn't find a z4jc or a z4c. I attached pix. I've been working on this so long im starting to get burnt out!

    Anyway I reinstalled the magnet and the magneto blue wire down. Keyway is at 1oclock position with piston at TDC. Blue wire to blue wire black to black. White is wrapped in tape.

    SO, Electrical system is ENTIRELY new, so is Fuel. I'm gonna check all my work over again before i try to ride. If it doesn't work i think im gonna have to sell it. I've been working on this so long im starting to get burnt out!
  9. joeltrain

    joeltrain New Member

    magneto install pix

    Attached Files:

  10. joeltrain

    joeltrain New Member

    plug pix

    Attached Files:

  11. motorpsycho

    motorpsycho Active Member

    well, you shouldn't have to mess with the float on a brand new carb.
    you should have just installed it right out of the box to see how it would run.
    then, make adjustments from there because it may have ran fine as it was.
    but now that you messed with the float, you may have to go back and re-adjust it.
    it all depends on how level your carb is because if it's at a slight angle, it still may flood over even tho you have the float set it at 19 mm.

    you're plug looks fine and it just looks like there's a bit of oil / carbon build up on it.
    it doesn't appear to be soaked with fuel.
    I'm not sure about those 3 prong plugs but i hear that they work pretty good. I personally like the ngk B6HS plugs.
  12. joeltrain

    joeltrain New Member

    The plug was soaked with fuel but it dried out b/c it has been out of the motor for several days. If that new plug doesn't work, ill try the ngk. I hate to wait for shipping. Do you know if autozone oreilly advance or pep boys carries that?
  13. joeltrain

    joeltrain New Member

    Still Wont Run

    Well I checked all my work and tried again. This time it would fire about 7-8 times and stall. Cyl was very warm. Have a 1/8mi hill to try on. Would always run by the bottom b4. Went back to house, tried other 2 cdi's. I am absolutely positive i have never hooked any cdi up wrong. Engine would not fire at all with either.

    I guess tomorrow i will try my other 2 magnetos with the cdi that wanted to run. I have labeled all cdis and magnetos so i dont mix them up. I am also journalizing this ordeal. I have been working on this for so long and done so much i'm not sure anymore what i have tried with what. So I'm starting over.

    The magneto that is currently installed is brand new. I am calling it #3. I am curious is anyone knows if magnetos can perform weakly. From what ive read it seems that they either work or dont. :ack2:
  14. joeltrain

    joeltrain New Member

    oh and btw, motorpsycho the new carb didn't flood. My adjustment to it was very slight as i said the primer pin was in the way so i really couldnt adj it anyway. Maybe 1mm. and I forgot to mention before that i sprayed starting fluid in the intake ,reinstalled carb and it still would not run. My prob has got to be weak or improperly timed spark. I made sure of the timing so the only thing left are mag's and cdi's
  15. ddesens

    ddesens Member

    Try hooking your cdi wiring up so it is black to black blue to blue. Have no wiring grounding to frame. It looks like you have your black wire grounded to the frame. Eliminate the kill switch entirely.
  16. joeltrain

    joeltrain New Member

    Still Nothing

    Tried Magneto #2 and engine actually ran for about 10 secs. This is with new plug. I installed an old plug three pronger stall immed on clutching.

    Pulled plug and rigged a new ground and a solid copper wire from cdi to plug. CDI #1 and 2 will only spark at 900 rpm on drill. CDI #3 wasted. Is there any way poss to partially fry cdi by having magneto with white wire up and blue down? If so they r prob ng cause i hooked the magneto upside down by accident. Oh well i continue to be stuck here.:icon_cry:
  17. joeltrain

    joeltrain New Member

    hi ddesens thats the way i have alway had it since it stopped running. It was running with that wiring setup.
    Last edited: Jul 20, 2011
  18. joeltrain

    joeltrain New Member

    It Runs!!!!!!!!!!

    A friend advised me to check to see if the muffler was clogged. Boy was it. I had a spare that the bottom fell off of. I found that the float bowl of a tecumseh lawn mower engine slides RIGHT OVER the end and IS ALREADY DRILLED for the stud. I just added one more hole 1/2 and put the nut back on and was ready to fly. Ran like never before, i think partially because of the new NT carb but almost completely because of the clog. All this work really allowed me to find out the best and strongest of all my parts. The new plug seems excellent. It is a E3 Diamond Fire. Model#is e3.12. I found it in the lawnmower section at a local autoparts store for $5.99. I recommend it. And it's much shorter which should help those of you who has fitment issues.

    I think this thread deserves a sticky. How does that work?.... and can you edit the title of your thread? I'd like to change the title to:
    will NOT run...NOW IT DOES
    Last edited: Jul 21, 2011
  19. ddesens

    ddesens Member

    Good info! I'm glad you got her up and running again.