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TRX 70 won't start

Discussion in 'Offroad Tech - Ask a Question any Question!' started by Tio Pancho, Dec 19, 2018.

  1. Tio Pancho

    Tio Pancho Well-Known Member

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    I have a 1986 TRX 70 I am working on for my grandson. It ran about a year ago. I just rebuilt the carb, changed the run/kill switch. Confirmed fuel flow into the carb bow and verified spark. Won't start even with spray.
    I am stumped. Any advice?

    Thanks

    Frank
     
  2. Ballsdeep

    Ballsdeep Well-Known Member

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    Buy a new carb, they are cheap.

    I just went through the same thing on a JR 50 I bought as a Christmas gift. Buy the OEM- dont wast your time or money on the cheap Chinese version from Amazon. I pulled the cheap one apart, cleaned, adjusted, etc.. very temperamental. Ordered a new OEM carb and it was delivered the next day. Slapped it on and it was running like a rapped ape within about 15 minutes.
     
  3. Tio Pancho

    Tio Pancho Well-Known Member

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    May do that. Just found a place that sells only ATC and TRX 70 parts.
    Thanks
     
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  4. outboard_256

    outboard_256 Well-Known Member

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    compression?
     
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  5. Tio Pancho

    Tio Pancho Well-Known Member

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    Didn't check it but hand over plug hole felt good. I will check it out today though. Thanks
     
  6. wsuwrhr

    wsuwrhr The Masheenest

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    Wild, not even a pop with spray?
     
  7. wsuwrhr

    wsuwrhr The Masheenest

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    I have an 86 TRX70 for my girls I bought when the first one was still in the womb.
     
  8. Tio Pancho

    Tio Pancho Well-Known Member

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    These things are awesome. We have had this one about 15 years. Got it for 300 bucks from a friend. Hardly even touched it except for basic maintenance.
     
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  9. Gelcoater

    Gelcoater Well-Known Member

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    Try bypassing the “new” off/run switch, and ensure it’s wired correctly and working. Double check your ground.
     
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  10. Gelcoater

    Gelcoater Well-Known Member

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    Also, ensure the vent in the gas cap vents;)
     
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  11. wsuwrhr

    wsuwrhr The Masheenest

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    Which is what IMA thinkin. He said he has spark though......

    These fuckin motors aren't that smart. a little fuel, some spark....out to at least "pop"
     
  12. outboard_256

    outboard_256 Well-Known Member

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    aside from compression also check the clutch. If I remember right the kickstarter/pull starter goes through the tranny side and through the clutch before it gets to the crank. If the clutch is slipping the crank isn't moving or moving slower than needed it could prevent it from starting. You will feel it slipping if it does as you can't feel the 4-strokes. Other extreme possible causes, bent valve, loose timing gear bolts, timing skipped a tooth, woodruff key sheared, CDI box (or points)/spark plug not producing big enough spark, warn rings, cracked cylinder. Doubt its any of these if it was running fine when you last used it though. I used to build/race 50's so I went through a lot of engines.
     
  13. Tio Pancho

    Tio Pancho Well-Known Member

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    Fuel, Air and Spark. Shouldn't be this hard. But like my dad used to say - It's the 3% rule. You need to be 3% smarter than the object you are working with.
    I will double check the kill switch. But I would think if it was bad I would have no spark.
     
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  14. wsuwrhr

    wsuwrhr The Masheenest

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    Yep. I say the same.

    "You got to be smarter than what you are workin on."
     
  15. wsuwrhr

    wsuwrhr The Masheenest

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    Are you sure it has spark? I mean, if you are spraying starting fluid in there and there is spark. It should at least pop.

    Is there a beetle that made a home in the bore of the carb?
     
  16. Tio Pancho

    Tio Pancho Well-Known Member

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    I pulled the plug, closed the garage door and turned off the lights to check spark (at night). There is spark. I sprayed starting fluid into the air cleaner. I just dont get it.
    I am leaning towards a timing issue.
     
  17. Gelcoater

    Gelcoater Well-Known Member

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    Pretty sure those engines run a points ignition for what it may be worth.
    You put a gauge to it to check what kind of compression it has?
     

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