2007 crf250r float height and carb setup questions
  • Devincijack91
    Posts: 4
    Joined: Tue Aug 03, 2021 12:15 pm

    2007 crf250r float height and carb setup questions

    by Devincijack91 » Tue Aug 03, 2021 12:53 pm

    Hi there ,
    Powersports newbie here, although I have some automotive background.
    I recently bought a new to me 2007 crf250r with a claimed 64 hrs, to teach myself about carbs ( careful what you wish for...)
    Bike ran fine on the flat tarmac road I tested it on. Once I took the bike out for a ride on a rough fsr it started bogging out / blubbering especially on inclines . This problem got worse when I went on track , landing on the middle of tabletops it would stutter/ bog , rolling through whoops on the uphill it would stutter and if I leaned it over too much on berms it would also cut out.

    So I decided to pull out the carb , before doing so I checked the AP timing , how strong should the squirt be ? From what I can tell it has the updated AP pump kit from Honda and a 70 leak jet. The squirt misses just the slide but lands inside the rubber boot between the carb and engine intake . Should it be making it to the R/H intake valve?


    I found some dirt in the float bowl and the o rings on the brass fuel L piece going into the carb were completely deteriorated , ordered a full carb rebuild kit and hoping this is the issue.

    My next question is float height , the manual says 6 mm and with the tip of a vernier gauge ( no access to float gauge) mine was 8mm but the tang looked level to the float and the mould line on the float was parallel with the gasket line ( how I understand Floats
    should be set as a base point if no measurement can be obtained )
    Setting the float to 6 mm it seems really high and on an incline, the the tang bent down at quite an angle. Does anyone know what these should look like if the top of there heads? I have the 40 mm carb so original , wondering if I have a non standard float or float needle....

    Thanks for any advice on float height and leak jet spray strength
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 2007 crf250r float height and carb setup questions

    by JimDirt » Wed Aug 04, 2021 11:51 am

    Welcome to the site !! \:D/

    What you can do is with the carb off , and the float bowl bolts removed , holding the float bowl on by hand , hook the carb to the gas line and turn on the valve and let it fill (it might help to have someone help with this) , then shut off the valve after about 20 or so seconds have passed , as that should be plenty of time to allow the bowl to fill , and gently drop down the bowl holding it level , and look to see how much gas is actually in the bowl , it should be more than half , but not to the top , as the space taken by the float should fill that space , if the bowl is lower than half , then yea , the float is too low .... but with a digital caliper , you should be able to get the correct setting , remember you are setting it with the carb sideways with the hinge for the float at the top

    This Caliper (inexpensive/cheap at Harbor Freight Tools) will work in place of a Float Gauge , it does mm and inch , so it should give you a accurate reading ..., and you can use it for all sorts of other things , like measuring the thickness of valve shims , etc. ....
    Image

    The float tab should be slightly pointing down as opposed to being flat

    Basically holding the carb sideways as mentioned with the float swinging free (hinge up) , it should just start to push on the needle when sitting level or slightly towards the needle from level
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • Devincijack91
    Posts: 4
    Joined: Tue Aug 03, 2021 12:15 pm

    Re: 2007 crf250r float height and carb setup questions

    by Devincijack91 » Thu Aug 05, 2021 7:26 am

    Thanks for the reply.
    That’s a really good idea Thankyou, I wasn’t having much luck with the clear tube method ( same result on different FCR carbs ) I’ll hook that up before re installing the carb and check.

    In regards to the AP squirt , all I can find is “ it should be a good strong squirt” should it be hitting the valve stems or just landing inside the intake ports somewhere ?
    Mines landing in the recess of the rubber boot between the carb and the head which I’m guessing isn’t ideal . Have a 70 leak installed but a 50 and a 40 leak on order

    Thanks again
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 2007 crf250r float height and carb setup questions

    by JimDirt » Thu Aug 05, 2021 8:43 am

    Basically as long as it just barely misses the slide you are good , the closer to it the better , as otherwise , the delay may cause a bog , but on the same note , if it hits the slide it will cause a bog , so you want it adjusted so it just misses the slide , then you should not have a bog , not sure how far in it is supposed to actually hit , maybe Leardriver can chime in with that , as he is the resident carb guru , so if anyone knows , it would be him ... but again , as long as it just barely misses the slide you should be good ;)
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho

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