Had trouble with new purchase and need to tear down the motor again, can I reuse brand new head gasket?
  • DaveyHK
    Posts: 1
    Joined: Tue Sep 11, 2018 1:02 pm

    Had trouble with new purchase and need to tear down the motor again, can I reuse brand new head gasket?

    by DaveyHK » Fri Sep 14, 2018 10:19 am

    Like the title says, I just picked up a 2006 crf450x for a great price. I tore it down to install SS intake valves and rejet etc. but upon reassembling, the base gasket that I installed is leaking oil (have read that it was probably for an R), and also the oil filter housing is leaking because the lower (longer) bolt stripped out the housing so I had to order a Helicoil kit to rethread that bolt. Now my question is when I FINALLY got it running (see below), I rode it for a grand total of maybe 20 minutes... do I have to repurchase a new head gasket after that little of use or should it be fine?

    Some other issues I was curious about that I ran into is about jetting. I know there are a million threads on this, and I followed them... Im in flagstaff at 7000 feet and summers temps have been consistent 70s and 80s, When I initially took apart the carb I put in 170 main, NCVS needle 3rd clip, 42 pilot, 55 leak and did the AP mod. The bike wouldnt start and when I finally had a friend mess with it he got it started but the exhaust was red hot. He claims it was a jetting issue but from everything I have read, those jet settings seem to be the most recommended. I pulled the carb again and put in a 165 main but did nothing else. I also pulled the header again and reseated the copper washer because i read i may have torqued it too much allowing air in the exhaust at the head (hence the read hot lean condition). after doing that Ive got it started but its not easy to start and the idle is pretty erratic(revving up and down). I cant get it started with the estart either, only kick start. where should I go next, I am waiting for the parts to come in at the start of next week so for now I am brain storming, but I definitely am getting a new copper washer for the exhaust. What could cause the idle to move so much up and down? Thanks for your time and any advice.
  • User avatar
    JimDirt
    Posts: 3015
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: Had trouble with new purchase and need to tear down the motor again, can I reuse brand new head gasket?

    by JimDirt » Fri Sep 14, 2018 5:17 pm

    Welcome to the site !! \:D/

    It sounds like you replaced the Needle , but not the Needle Jet , that is the long tube the Main Jet goes in and sticks up thru into the venturi , if the Needle itself had any signs of wear (the old one) , then it most likely ovaled out the Needle Jet , and that allows the Needle to kind of bounce around , allowing it to sort of seal , then allow fuel passage in the worn out area , so what the bike does is surge fuel when its in the sloppy part of the tube , so you get RPM changes as fuel is increased , then restricted .... make sense ??

    Replace the Needle Jet and you should be good with that , i would also replace the Floating Valve Seal , it is the O-Ring looking thing on the plate that comes off the slide , if its bad it can also cause erratic idle issues , make sure when removing it , to note the orientation of the Floating Valve Plate , it needs to go back together "exactly" as it came out ...... As far as the header glowing , they do glow anyways when the engine is run as they are around 1500 degrees when at a idle , if you ran the bike at night in the dark you would be amazed at how red the header gets , and its made worse when your just sitting there running without any airflow helping cool the header .... with that said , i would replace the Pilot with a #45 instead of the #42 , its too lean on the bottom end from the factory and keeping the smaller pilot makes you fight tuning , but its too rich on the top end , so you need to drop the main jet size also go make it run better . i run a 45/160 at 2000 ft

    Here is a Jetting Guide made up by the resident carb guru here ... (Leardriver) , run what it says and you should be good

    Jetting Guide for Main Jet:(pilot 45) CRF450R/X

    Sea level....165
    2000 ft.......162
    4000 ft.......160
    6000 ft.......158
    8000 ft.......155


    Temperature/Elevation:
    One main jet size (up/down) for every 2,000 feet or 25 degrees in temp.
    Last edited by JimDirt on Sun Sep 16, 2018 10:12 am, edited 1 time in total.
    02 CRF450R
    06 CRF450X
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    Weiser , Idaho
  • Leardriver
    Posts: 324
    Joined: Wed May 05, 2010 10:33 am

    Re: Had trouble with new purchase and need to tear down the motor again, can I reuse brand new head gasket?

    by Leardriver » Sun Sep 16, 2018 8:38 am

    That will be a great bike for you. It just needs a tweak or two.

    All 450's need a 45 pilot at about 1 7/8 turns out on the fuel screw. For your altitude, a 158 main is fine. The bikes are very forgiving to being off a few sizes on the main, but if you are in the carb and fiddling with it, you might as well get real close.

    I have been guilty of re-using a base gasket, but never a head gasket.

    Those bikes will get hot as blazes idling and not moving. That doesn't mean that something is wrong, it just means that it is tired of idling and wants to go riding. My horse will start pawing the ground after his saddle is on, he is ready to go to work.

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