2003 XR70R High rev sticking
  • Tws1977
    Posts: 3
    Joined: Fri Jul 31, 2020 5:07 pm

    2003 XR70R High rev sticking

    by Tws1977 » Fri Jul 31, 2020 5:10 pm

    Took the carburetor off and cleaned it up. Everything seemed to go back together fine and it ran pretty good for a little while, but now this is what it's doing:

    It cranks fine and idles fine, but when I give it a little gas, it revvs really fast and won't go back down, so I have to kill it. I thought the throttle needle and slide might have been inserted wrong , so I keep disconnecting it where it inserts into the top of the carburetor, and it seems to be pushed up too far (the spring pushes the throttle cable nut up as soon as it's disconnected, like the slide has retracted too high out of position.) I can replace the throttle needle and slide back into the carburetor, and there doesn't seem to be any stickiness, it seems to go down and up freely. I re-tighten the throttle cable connection, and it cranks fine, but as soon as I give it a little gas, it jumps into a high rev again and won't go back to an idle. 

    Im not a mechanic so I might have some of the terms wrong here, but hopefully I've explained the problem clearly. 
  • Aussiecrf230
    Posts: 1724
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2003 XR70R High rev sticking

    by Aussiecrf230 » Sat Aug 01, 2020 3:27 am

    Hi Tws1977 and welcome to the site.
    If the knurled slide nut is pushed up when you unscrew it that is pretty normal assuming the spring is sitting in the piston and is against the nut.

    If the slide moves freely in the carb body I would tend to look at either a throttle cable that needs lubing or is catching on the liner due to damage or being routed so it is tight.
    Also make sure the throttle tube on the handle bar isn't sticking as well.

    A lean condition at idle can also make it idle fast and not return to idle.
    Could be small airleak or just needs adjustment of fuel screw.

    See how you go and let us know what you find.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas
  • Tws1977
    Posts: 3
    Joined: Fri Jul 31, 2020 5:07 pm

    Re: 2003 XR70R High rev sticking

    by Tws1977 » Sun Aug 02, 2020 11:57 am

    The throttle cable doesn't feel sticky at all when it's reved from the carburetor. It's seems to retract and return freely. (I did lube it as best as I could though.)
    I did notice that when the bike is not running, when I rotate the throttle handle, I hear a "click" where the throttle cable connects to the carburetor, and the throttle handle doesn't return to its original position. It seems like the slide (piston?) is able to retract up and out of position, and then cannot return down to it's idle position. What keeps the slide from retracting up and out of position if everything is working properly?
  • Tws1977
    Posts: 3
    Joined: Fri Jul 31, 2020 5:07 pm

    Re: 2003 XR70R High rev sticking

    by Tws1977 » Sun Aug 02, 2020 2:56 pm

    The first sentence on the previous reply should say, "removed from the carburetor."
  • Aussiecrf230
    Posts: 1724
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2003 XR70R High rev sticking

    by Aussiecrf230 » Sun Aug 02, 2020 3:10 pm

    The spring in the carby helps keep slide closed, but everything has to be free.

    Sounds like you need to remove throttle tube to check things out.
    The inner cable maybe damaged at catching.

    With the throttle tube off see if it still sticks.
    You can disconnect the throttle cable at both ends and check throughly.
    It only takes a little bit of water to get in and rust a bit for one of the fine wires to fray and catch.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas
  • Aussiecrf230
    Posts: 1724
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2003 XR70R High rev sticking

    by Aussiecrf230 » Sun Aug 02, 2020 7:26 pm

    We both must having been typing at same time as didn't see the removed correction first off.

    Can't remember if this can be done, but does the slide only go in one way around?

    If the piston isn't dropping, is the needle catching on the needle jet( the hole it goes into). There would be rub marks on the needle.

    The other possibility is needle isn't sitting properly in piston or is bent.

    Have a look at those few things. A black marker pen can be used to mark a surface to see if there is contact.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas

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