05 CRF 450X Backfires / no start
  • phenomenon
    Posts: 3
    Joined: Thu May 31, 2018 8:25 pm

    05 CRF 450X Backfires / no start

    by phenomenon » Thu May 31, 2018 8:32 pm

    Hey guys, i'm working on a friends 2005 Honda CRF 450 X that wont start.

    Has great compression (ask my leg haha), had the carb "sonic" cleaned, checked the valve clearances (all in spec except left intake is .008 so a tad bigger then its supposed to be).

    No matter what i do (even starting fluid) it will only backfire, doesnt even try to catch and start.

    I'd love to use the electric start but the starters burnt out from previous owner, battery is brand new though.

    I'm about out of ideas ](*,)
  • Leardriver
    Posts: 462
    Joined: Wed May 05, 2010 10:33 am

    Re: 05 CRF 450X Backfires / no start

    by Leardriver » Fri Jun 01, 2018 1:57 am

    When is the last time that it ran? I would be suspicious of sonic cleaning. It might make parts of the carb pretty, but did it clear out the pilot jet, the passageway above it, the fuel screw and passage above it? I take both of those out and blow air and carb cleaner in the holes, probe them with a dental pick, and check for air getting through into the carb bell. Replacing the pilot jet is a much safer method than cleaning it. It is a cheap part.
  • phenomenon
    Posts: 3
    Joined: Thu May 31, 2018 8:25 pm

    Re: 05 CRF 450X Backfires / no start

    by phenomenon » Fri Jun 01, 2018 5:35 am

    it hasnt been ran in a while, before sonic cleaning i spent hours digging out green guck and removed/cleaned the jets and holes.

    the only thing i havent checked is the timing, i know the chain is tight but that doesnt mean it hasnt skipped a tooth.
  • User avatar
    JimDirt
    Posts: 4406
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 05 CRF 450X Backfires / no start

    by JimDirt » Fri Jun 01, 2018 8:12 am

    Welcome to the site !! \:D/

    Kind of a obvious question , but , was the gas drained and FRESH Premium put in ?? , if the bike sat more than about 2 months at most , the gas will be only good for the lawn mower , not these bikes , also running Non-Ethanol , is best and will eliminate that green crap in the carb , its residual from Ethanol (basically water)

    Also , look carefully at the coil , which is located in the front of the frame cradle , on the ignition side of the bike on top of the coil is a plug in for the main power to the coil , sometimes when removing the tank to check valves , etc. , the gas line (because its bulky with 2 hoses) has to be pulled out right next to the coil , and the petcock gets caught on that wire and unplugs it , it may look connected (or not) but its not and you will not get any kind of fire

    Also as Leardriver mentioned , its about $6.00 for a Pilot jet , unless you have a K&L Carb Cleaning Tool , or equivalent , chances are , if the carb was green inside , the jet is still clogged , i would also remove the Fuel Screw and check the O-Ring , if its damaged and the pilot is clogged , you will have a extreme lean condition .....What you can try as a test to see if it is in fact a lean condition , is , pull the spark plug , and dip the electrode in gas , then reinstall it , and try to start it , if it pops or fires , then you have ruled out any ignition or other issue and your back to something is still clogged inside the carb , weather it be a passage or a jet

    If what you cleaned the jets with was not this , then most likely , the jet is not clean https://www.crfsonly.com/catalog/produc ... ts_id/4294

    Before you worry about Timing , eliminate a fuel issue , 1 thing at a time will find the issue , rather than tearing everything apart and hoping you don't overlook the obvious


    Report back with findings .... ;)
    2020 CRF450R
    2006 CRF450X
    Image
    Weiser , Idaho
  • phenomenon
    Posts: 3
    Joined: Thu May 31, 2018 8:25 pm

    Re: 05 CRF 450X Backfires / no start

    by phenomenon » Fri Jun 01, 2018 2:46 pm

    Fuel is fresh from the pump haha.

    I checked the coil wires and they are indeed plugged in, also has a nice strong blue spark.

    Thats the same tool i used actually, after cleaning it manually i also had a buddy sonic clean the carb.

    I re-checked the valve clearances last night, right intake .006, left intake .008, exhaust both measure .011 (all in spec i believe).

    Stupid part is even using ether, all it does is backfire through the carb.

    I'm just baffled by this bike and normally i can get anything to run.

Who is online

Users browsing this forum: No registered users and 2 guests