HS 142f bucks and cuts out when cruising

Discussion in '4 Stroke Bicycle Engines & Kits' started by worksuxxx, Sep 5, 2013.

  1. worksuxxx

    worksuxxx New Member

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    OK, I am taking a break from this one. While I do so, I am looking for some input. This engine idles perfect, accelerates properly. But when I hold the throttle and try to maintain speed it bucks and cuts out. I haven't gotten it past 6000 rpm to see the upper range, still breaking it in. I have adjusted the valves, cleaned the carb, changed the plug to a NGK. I wouldn't think spark would be the problem since idle and acceleration is good. So I am ruling out the magneto. It has done this since install 3 days ago. Oh and I have tried to lean it out but no luck. The spark plug was black when I pulled the original out. Most importantly, when I turn the air/fuel screw in all the way, it revs higher and does not die like my other engines did. I guess maybe I will steal a carb of another kit to see if that changes anything. Be back with results on that one in about an hour.
     
  2. worksuxxx

    worksuxxx New Member

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    Just swapped new carb from another kit. Does the same thing. If I hold rpm it bucks and jerks. Idles fine, accels good. Stumped...
     
  3. BigBlue

    BigBlue New Member

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    Check the spark plug wire for breaks. Move the wire with the engine idling to see if that causes the engine to buck and jerk. Just be sure to grab it with something that has insulation, so you don't get shocked. Also check to make sure the magneto coil is securely fastened.

    Chris
    AKA: BigBlue
     
  4. worksuxxx

    worksuxxx New Member

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    Lol... I gave up on that motor. I changed out the magneto and plug wire, spark plug, carburator, thought I did the valve adjustment right three times. So I swapped out with another motor from the other kit I bought from gasbike.net as well. Guess what? Same dang problem. Uggggghhhh! Give me a break lol. I am soooo frustrated with this. How can it accelerate good but holding rpm seems like its missing? Valve adjustment seem to be the cause? Maybe I am not doing it right. .004 intake .006 exhaust. Cold engine. The exhaust seems to be putting out alot of pressure compared to my other builds. I am using the box exhaust that comes standard. I also hear a constant intermittant noise like a thunf thunf thunf from the exhaust. I need a beer..........
     
  5. BigBlue

    BigBlue New Member

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    Constricted/restricted/collasped muffler?

    Chris
    AKA: BigBlue
     
  6. worksuxxx

    worksuxxx New Member

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    On both motors? The only thing the same is the fuel tank. I am going to take off tank, clean it, put new fuel in. Then clean carburators real good and try again. I am thinking trash might have gotten into the carburators. Usually though I feel a problem with accell, not holding speed.
     
  7. BigBlue

    BigBlue New Member

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    Call a day and have a couple more cold ones. Take a few days to think about it.

    Chris
    AKA: BigBlue
     
  8. worksuxxx

    worksuxxx New Member

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    Cleaned the fuel tank, replaced fuel peacock and filter. Cleaned carb again, changed spark plug and magneto again. Unhooked wiring to kill switch, tried adjusting carb. Still does not run smooth. Twisting up to about 35% throttle it cuts out pretty bad. Give it more throttle and it smooths out. Still surges when trying to hold any rpm while cruising. Amazed two engines ordered same time from gasbike.net would be doing this. One I can believe, not both. While adjusting carb I noticed I can close the air/fuel screw and it still runs. Shouldn't it die with it adjusted all the way in? Actually tried to call gasbike.net earlier to see if they could shed some light, but of course was on hold for way too long and gave up. Not sure if they have any techs there or not. I personally think it is running overly rich. I have done everything I can possibly think of other than change the box muffler with an exhaust pipe. These two motors are much louder than my previous 4 stroke builds. And there is alot of exhaust pressure coming out, I would say at least twice as much pressure from what I have seen from my other builds.
     
  9. worksuxxx

    worksuxxx New Member

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    Update. Let it idle today for the first time for about 3-4 minutes. Had air screw turned all the way in. As it warmed up idle rpm dropped and could see little bit of black smoke coming from exhaust. Give it gas and small puff of black smoke. Kept idling, finally died. Will not restart. Full throttle pull start and it starts but very low rpm then dies. Guessing I should change the oil before messing with it just in cast washed out with fuel. Am I missing something clogged in the carb to make it run very rich? Or could the exhaust box be causing too much back pressure leading to this problem?
     
  10. Jim C

    Jim C New Member

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    it sounds like a fuel delivery problem. Have you changed the air filter? Is the choke butterfly holding open? Is a carb needle loose? Air leak? Dirt in gas tank. One time on my 72 Norton I had plugged the gas cap vent hole with wax and fuel would not flow if I opened the cap it vented the tank and fuel would flow, solved that mystery with a paper clip
     
  11. GearNut

    GearNut New Member

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    My best guess is it is tuned too rich. Either the wrong jets (seems highly unlikely though that the factory would do this) or more likely too high of a float setting; and yes, it also sounds like the choke could be in the closed (on) position.
    Check the color of your new NGK spark plug. Is it black or really dark brown?
     
  12. worksuxxx

    worksuxxx New Member

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    My first build I learned the correct choke position. It will not run with choke on, which should mean no air leaks. Sprayed carb cleaner around carb with no change to engine idle except the black hose going into crankcase. I know there is a primary jet (under idle adjustment screw), where are the other jets? Carbs are not my thing. The float did not look adjustable when I was in there. Also like I originally said, both engines from this vendor ordered at the same time are doing the same thing. I have replaced the gas, tank and fuel line with filter. The only thing I have not changed is the mufflers (box). I don't know if it matters, but the longer it runs the worse it gets, along with losing power.
     
  13. worksuxxx

    worksuxxx New Member

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    GearNut, the plug is always black and smells like fuel.
     
  14. worksuxxx

    worksuxxx New Member

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    Just checked the float operation. It is good. Stopped flow right at horizontal. Know now the main jet. Unfortunately is not stamped with a size. I guess anything is possible when it comes to be jetted too high from factory with both engines. Just checked the tags. Here are the manufacturing dates and serial numbers.

    Serial #130300310 3/25/2013
    Serial #130300266 3/26/2013

    I am assuming It is possible being 44 builds apart the assembler could have messed up a batch meaning I got two engines with the exact same problem.

    Where do I get different jets for these little motors. And does anyone know the correct size that goes in these from factory?
     
  15. MotorBicycleRacing

    MotorBicycleRacing Active Member

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    Does you Carb have the brass plug over the air mixture screw?
     
  16. worksuxxx

    worksuxxx New Member

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    It did. I have tried adjusting. I can adjust screw all the way in, and it will still run. Actually runs better but still no where near what it should.
     
  17. MotorBicycleRacing

    MotorBicycleRacing Active Member

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    Screw should be about 2 turns out.
     
  18. Tinsmith

    Tinsmith Member

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    Mr Suxx, My HS cuts out occasionally when I'm cruising, most often on a long uphill grade, but sometimes when I just get into it real good. It aggravating, but for the most part it starts, runs, idles good and has been reliable for two years. I feel like it's a fuel delivery problem, but not being a real "motor nut" i've decided to accept it for what it is. I'll be interested to see what you figure out.

    Good Luck, Dan
     
  19. worksuxxx

    worksuxxx New Member

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    I have built four other 4 stroke builds this month. I know how this motor should run, and the way its performs now is very unacceptable to me. I know it is a carb issue, running rich. I have been trying to get a live person on the phone over at gasbike.net for days. Finally got someone to answer the phone today. When I asked to speak to a tech, they said tech will be in at 11am. I called promptly at 11am, was then told tech will be in at noon. I called back at 1pm, was told tech will not be in til Monday. Interesting enough when they answer the phone it was a "hello", not very professional. I will call back on Monday, if no tech, then I will return their kits and dispute the charges with my bank, and order from someone else. As a purchaser of a product from a company, I don't care what company it is, the product should work out of the box. A few simple adjustments I might understand, but this apparently surpasses simple adjustments. I might be frustrated, and problems like this are a learning curve to look at it as a positive, but at some point a bad product needs to be replaced without hassle or paying out of pocket to ship it back to them. If I buy a $10 toaster at Walmart would I take it apart to fix the problem? I simply want to pay money for a product and expect it to work out of the box. Thanks for all the replies everyone, but I am gonna pass on fixing these two engines and order a couple more in as replacements.
     
  20. xseler

    xseler Active Member

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    Have you tried a different gap on your spark plug?

    I have a Honda lawn mower that is very sensitive to the gap.
     

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