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Help with beta rev3

Discussion in 'Trials' started by COXR650L, May 18, 2018.

  1. COXR650L

    COXR650L Long timer

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    I got my first trials bike, a 2000 beta Rev 3 270. Bike ran good when I got it. Typical older bike so I pulled some stuff apart to sort it out. While at it I pulled the carb and cleaned it. I set the float to what I read online with the tangs pointing at the piolt jet tower (the tangs were level when I opened it up) new plug etc.

    I get it all back together and it starts ok ride down the driveway, bike is running a little irratic with a high idle. Turn it off adjust the idle screw, start it back up and it begins reving uncontrollably. The kill switch will not even turn it off. Finally it turns off. Now when I try and start it all I get is an occasional back fire through the exhaust.

    I pulled the carb again and blew it out and cleaned the pilot. Still no change Tried raising the float level and again nothing.

    Plug is wet with fuel and getting spark.

    Any ideas?
    #1
  2. NMTrailboss

    NMTrailboss Team Dead End

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    Lineaway should be along shortly! :deal
    #2
    thegraydog likes this.
  3. Nobade

    Nobade Been here awhile

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    Sounds way too lean like you lowered the float level too much. Or partially plugged pilot jet, or an air leak somewhere.
    #3
    REALGRAVEROBBER likes this.
  4. heffergm

    heffergm Long timer

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    Pinch the throttle cable somewhere when you were putting things back together? Even if your float level is way off, the bike would just run lean, not rev uncontrollably. Same with a plugged jet.
    #4
    jonnyc21 and DyrWolf like this.
  5. Gordy

    Gordy Team Listo

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    What do you mean " start it back up and it begins reving uncontrollably. The kill switch will not even turn it off. Finally it turns off".

    What did you do to finally get it shut down?

    You aren't confusing this with how a bike will momentarily rev up real high and then gradually shut off when the petcock (or supply) is shut off are you?

    The only way that bike will rev uncontrollably is if something is holding the slide up. Either your adjustment screw or the cable.
    #5
    jonnyc21 likes this.
  6. COXR650L

    COXR650L Long timer

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    I pulled the carb for the 3rd time, recleaned it and put the float tangs back to roughly level. I put the old spark plug in again verified it was getting spark. It will not even try to start

    I have no explanation for why it ran the way it did. I seems the throttle was working smoothly and I rode it for a min or so. When I restarted to adjust the idle it revved up to around 5k rpm and stayed there for about 30 seconds while I tried to adjust it. The mixture screw and idle screw would not change the condition. While it was running the engine would cut out several times, only for a split second. I held the kill switch down and it did nothing. I turned the fuel off and it finally died.

    Now it won't even try to start other than a few random back fires
    #6
  7. MATTY

    MATTY BORDER RAIDER

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    Start from scratch basics check Spark nice fat and blue, is fuel getting there and if it is as it still got crankcase compression?. It could be a issue separate from what you disturbed .
    #7
  8. Nobade

    Nobade Been here awhile

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    I wish that were the case with my old RD400 that blew up because it got leaned out so far I couldn't stop it due to plugged pilots. But yes, a stuck cable is a more likely cause I skipped over. Now it's gotten more interesting...
    #8
  9. COXR650L

    COXR650L Long timer

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    Thanks for the help guys.

    Yes spark is blue and looks normal as far as I can tell. The plug is wet with gas when I pull it so I'm assuming it's getting fuel.

    I'm going to test the compression next, but I need a 90 degree elbow to fit under the tank. Headed to the hardware store now
    #9
  10. heffergm

    heffergm Long timer

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    Have you let it sit with the plug out since it last refused to start? It might just be unrelated flooded.
    #10
  11. 2whlrcr

    2whlrcr gooligan

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    Next time it rev's out of control, just put a gloved hand or rag over the exhaust. It will die quickly without drama. Or if you're looking for a jolt, pull the spark plug cap off.
    #11
  12. jonnyc21

    jonnyc21 Trials Ninja

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    Have you considered its running extra lean because the tank petcock is blocked? if it stopped quickly when you turned the fuel off then maybe its not getting all the fuel it needs? Maybe consider using a different fuel source to double check?

    Also consider a stuck needle in the floats?
    #12
  13. COXR650L

    COXR650L Long timer

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    Well this one is beyond me. Fuel flows from the tank just fine, spark at the plug, plug is wet with fuel when I pull it, carb has been cleaned and blown out several times, and now I've even used starting fluid and nothing. I think all that's left is compression? Maybe it broke a ring.......

    The first hardware store did not have anything to make a 90deg fitting for my compression tester. As soon as I find something that will work I'll see what the compression number looks like. Not sure what else it could be.
    #13
  14. Brewtus

    Brewtus Buffoonery, Inc.

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    Line is in Turkey Rock, Colorado at a MWVTA event this weekend. Give him a bit of time.

    Not being a smartass here but... Slide in correctly? :dunno
    #14
    lineaway likes this.
  15. COXR650L

    COXR650L Long timer

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    Yeah, I even checked that. Only fits one way. Haha. I'm not a professional mechanic, but have spent my entire life working on vehicles of some kind. I've had my fare share of dumbassery, but this seems pretty simple. I just can't figure out what Im missing, or possibly fucked up.....
    #15
  16. lineaway

    lineaway Long timer

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    You probably sheared a flywheel key. So was the carb over flowing that you tried ti fix a new bike? You need to make sure that you HEAR the slide hit bottom. Did you remove any wiring or the radiator? You might have a loose ground.
    #16
  17. Vintage pro

    Vintage pro Been here awhile

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    Go out and start the bike, does it run better with the choke to enrich the mixture, sounds like a airleak. The enriching will tell the story.
    #17
  18. heffergm

    heffergm Long timer

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    Except as he mentioned it doesn't run at all.
    #18
    10K likes this.
  19. lineaway

    lineaway Long timer

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    You can pop the top off the throttle assembly to make sure the slide bottoms. Being what happened you could now have a cold seize, which means you nipped the piston. Take off the front exhaust and look at the piston. It should be obvious on the exhaust side if you did this. Besides it gives the fuel time to evaporate.
    #19
  20. COXR650L

    COXR650L Long timer

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    Ill pull the header and check tomorrow, but I'm guessing your right. Idle was probably high with the carb pulled apart, maybe a bad ground on the kill switch so it didn't stop the engine, or a very lean condition from the float change, and revving a cold engine=o no.

    Let's hope top ends are too expensive.
    #20