Crf wont start (4 year ongoing problem)
  • EoghanW
    Posts: 5
    Joined: Sun May 17, 2015 3:50 pm

    Crf wont start (4 year ongoing problem)

    by EoghanW » Sun May 17, 2015 4:09 pm

    Hi,

    Have a 2004 250r which I've owned the last 4 years but I've never been able to get it started. Over last few months I've totally rebuilt it but I'm left with same problem I've had since beginning.

    Has brand new head, valves, spark plug, piston, crank, every bearing incl gearbox, oil pump, gaskets and seals etc. Carb was totally stripped and cleaned. Valves and timing are prefect. Jetting is stock.accel and hotstart cables, cdi, coil stator and loom replaced.

    Symptoms are as follows.

    Can't start with kick when cold(flames out exhaust when cold kicking)
    Will start with bump start
    When warm will kick start but alot of kicks
    Will not idle
    Idle screw has no effect at all

    Anyone got any ideas? To me it's like it's running very leak or has a airleak but I can't find anything.

    I started to wonder if the boot between the carb and head was drawing in air but looking at it would seem like likely to fail.

    Anyone help me before I give up.
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    JimDirt
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    by JimDirt » Sun May 17, 2015 6:39 pm

    It sounds like a lean condition , did you check the function of the Hot Start lever AND where it goes into the carb , when the carb was cleaned , was the Hot Start plunger that goes into the carb cleaned so its shiny ??

    What is your elevation ?? , it could be that from the beginning the bike was not jetted for your altitude , and what size jets do you currently have in it (Main and Pilot) ??

    Have you made sure the header where it goes into the head , as well as the mid pipe connection is tight and not leaking , it either leak it will cause lean symptoms

    Did you replace the Floating Valve Seal in the carb ?? (the flat plate with the rubber on it that is part of the slide) , and did you put it in Carb Cleaner ?? as that will ruin it

    Have you pulled out the Fuel Screw and confirmed that the O-Ring and Washer and Spring are all intact and in that order ?? (O-Ring near the tip , then washer , then spring near the handle/adjustment end)

    Have you confirmed you float level is correct and that there is sufficient fuel in the bowl ??
    2020 CRF450R
    2006 CRF450X
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    Weiser , Idaho
  • EoghanW
    Posts: 5
    Joined: Sun May 17, 2015 3:50 pm

    by EoghanW » Mon May 18, 2015 1:32 am

    Cleaned hot start but not shiney will redo.
    I'm sea level and jets are as per workshop manual. 40 and 162 I live in Ireland so temp is - 4 to 16 degrees.
    Header is ok new copper seal.
    Never even knew about floating seal so I'll pull it out and check it.
    Fuel screw is new quick adjust aftermarket one new spring seal and washer.
    Float level was checked and is ok. How do I check if sufficient fuel in bowl?
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    JimDirt
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    by JimDirt » Mon May 18, 2015 7:19 am

    I would go 45 on Pilot , 40 is too lean

    And in those cooler temps (4c) you should be at least 1 size richer on jetting , as the temp warms , then be where your at (at 16c)

    When you installed the new Fuel Screw , are you positive you got out the old O-Ring and washer ??, this could create a lean condition

    The easiest way to check the fuel level is to drain the carb bowl , re-tighten the drain screw or bottom nut , pull the carb and undo the float bowl , then set the bowl in place but with no screws holding it , then connect the fuel line with the carb next to the engine (outside the frame) , then hold the carb level by cupping the bowl and turn on the fuel , wait about 20-30 seconds , then shut off the fuel valve , while still holding the carb level ,hold the carb itself with one hand , and with the other lower the bowl , and see where the level is , it should be about 3/4 full

    You can do this with the carb in place , as well , but its kind of tight , you need to twist the carb enough so you can get the bowl screws out , then put it back level and do as mentioned above
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • EoghanW
    Posts: 5
    Joined: Sun May 17, 2015 3:50 pm

    by EoghanW » Mon May 18, 2015 2:44 pm

    JimDirt wrote:I would go 45 on Pilot , 40 is too lean

    And in those cooler temps (4c) you should be at least 1 size richer on jetting , as the temp warms , then be where your at (at 16c)

    When you installed the new Fuel Screw , are you positive you got out the old O-Ring and washer ??, this could create a lean condition

    The easiest way to check the fuel level is to drain the carb bowl , re-tighten the drain screw or bottom nut , pull the carb and undo the float bowl , then set the bowl in place but with no screws holding it , then connect the fuel line with the carb next to the engine (outside the frame) , then hold the carb level by cupping the bowl and turn on the fuel , wait about 20-30 seconds , then shut off the fuel valve , while still holding the carb level ,hold the carb itself with one hand , and with the other lower the bowl , and see where the level is , it should be about 3/4 full

    You can do this with the carb in place , as well , but its kind of tight , you need to twist the carb enough so you can get the bowl screws out , then put it back level and do as mentioned above


    I will get them jets but still shouldnt be as bad as it is now so isnt the problem.

    Fuel screw is 100% no extra seal etc.

    I have removed the carb. Float valve seal looks ok.
    Hot start plunger is free and ok. Just have to check fuel level.

    One thing i noticed which may be normal but when i kick the bike over with the choke off i can hear air leaking noise around the carb area. If i put the choke on the noise is gone?? Could this be something or is it normal?

    Thanks
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    JimDirt
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    by JimDirt » Mon May 18, 2015 4:26 pm

    Are you sure your not hearing the De-compressor ??

    The choke would only richen the mixture , it should not make air blow by or anything , , are you positive the boot is sealed ??

    There is something you can try , but only start the bike briefly , and only do this with the engine cold so the exhaust is cool

    Take some carb cleaner , and spray it on the intake boot , just a quick squirt, if there is a leak the idle will change , do the same on the airbox side , try not to hit the exhaust with the spray as it will get hot fast , and things will get even hotter real fast , if that happens , then break out the marshmallows , let engine cool , then fire it back up and spray the carb directly , if nothing changes the idle , then you have no leak and the issue is either in jetting or something internal in the carb , or Intake valves or stator , that would be it
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • EoghanW
    Posts: 5
    Joined: Sun May 17, 2015 3:50 pm

    by EoghanW » Tue May 19, 2015 2:14 pm

    Im not sure i just noticed the noise stopped when i put choke on. i only hear it when kicking slow,could be normal as first CRF ive owned.

    Boot is sealed ok check for cracks etc and has new clamps etc.

    Going to check fuel level and for leaks with carb cleaner once i put carb back in.

    One thing also im not sure about is i completely stripped the carb bare when cleaning. So i had TPS sensor off. I set with as per workshop manual. But i have the idle screw (side of carb) completely backed off not touching the throttle. Is there a setting this should be at? Was reading that if i adjust it ill have to re-adjust the TPS? How do i set up both off the bike as when i install the carb i cant set the TPS as screw isnt accessible?

    Cheers Eoghan
  • User avatar
    JimDirt
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    by JimDirt » Tue May 19, 2015 4:11 pm

    This is the Service Manual Specs for adjusting the TPS for your bike , you move the TPS till it gives those readings , also , there should have been a Paint Mark , like a yellow or white line , where the TPS should be set on the carb body and the TPS mark should line up (this is they you always mark or take notes as to the position of parts BEFORE dis-assembly

    The idle screw can only be set with the bike running , what you need to do is turn the screw till it just starts to move the slide , then finalize after firing the bike , you may have to manually hold the throttle open till you get the screw in enough to allow it to idle on its own , THEN once the idle is set , then unplug the TPS and test and adjust as shown (hopefully your manual showed this) after you shut off the bike , but you need to set the idle first with the bike running

    Image
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • brownedoff
    Posts: 44
    Joined: Thu May 08, 2014 12:51 pm

    by brownedoff » Thu May 21, 2015 2:40 pm

    Get fresh petrol in there paddy . Check pipe between carb n cylinder check hot start . Bump it get in running for 5 mins mid rev try to gadge what the bike sounds like to identify problem chech spark plug for carb adjustments also air mixture screw only makes any difference the first few screws so keep it at 1 turn out to start with ... Blow carb out with airline and leave no deposits in there goood vid on youtube
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Thu Jun 18, 2015 12:00 pm

    Any update on this? If you had to back the idle screw out all the way to get the proper TPS reading, then you either installed the TPS incorrectly or the TPS is bad. It sounds to me like you just need to get the idle screw and TPS adjustment squared away and you'll have a running bike. BTW, the bike will run without the TPS connected, so I would try that first. Set the fuel screw to 2 turns out and keep adjusting the idle screw clockwise to raise the slide until hopefully the engine starts.
    2007 CRF250X
    2004 CRF230F (sold)
  • EoghanW
    Posts: 5
    Joined: Sun May 17, 2015 3:50 pm

    by EoghanW » Wed Jul 22, 2015 3:20 am

    Update is I gave up and brought it to a shop. They replaced carb with second hand one I had here and bike now runs and idles fine.

    Not sure whats up with the old carb tho. All jets where new also seals too. And TPS sensor was set up correctly by bike shop too.
  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Mon Jul 27, 2015 7:36 pm

    Hmmm. We, at least you got it running again.
    2007 CRF250X
    2004 CRF230F (sold)

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