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Thread: 300ex just rebuilt the head and smoking worse than before

  1. #1
    Join Date
    Sep 2009
    Location
    Bangor PA
    Posts
    26

    300ex just rebuilt the head and smoking worse than before

    Ok so I decided to tear my head apart and and replace my worn out cam..... while i was in there i realized i needed rockers replaced those and also replaced the valve seals because it smoked like crazy, but had excellent compression and ran fine..... NOW i have a couple new problems (isnt that how it always works lol-----

    1. It is pumping out white smoke like a steam engine locomotive.... while it doesnt smell like oil at all, i cant figure what else it could be I havent rode it around enough to see if it uses any oil for fear of damaging the engine.. It did sit outside under a tarp for a month with no head on it but i kept going out and moving the piston a hair and putting a small amount of oil in the cylinder... The carb however hung upside down off the side of the bike after getting knocked off the edge of the frame where i had it sitting and seemed to have collected a little bit of water one night...

    2. its hard to start takes a few tries to get her to sputter and then fires off to a rough start.... It ran perfect before despite burning a qt or oil a day and I am positive it its timed correctly.

    Here are my theories
    It is burning off residual oil in the muffler from riding it for a year with bad valve seals and loading it up with oil........ If so how long do you imagine it would take to burn that off condsidering it has a white brothers e series pipe with the baffles and plate blocking the end

    or

    its moisture in the case and carb from being outside in the damp air
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  2. #2
    Join Date
    Mar 2010
    Location
    Armagh, PA
    Posts
    1,366
    when it is burning oil it is most likely going to be a blueish white smoke

    When i bought my 426 as a basket case i finished it and got it running and it was smoking like a chimney but it was whiteish blue smoke well i rode it around a little while figuring it may just be residue in the pipe and it cleared up after about an hour or so

    But it had the free flowing WB r4 pipe

    I think it was run for a while when it needed rings and valve seals

    Could it be rings?
    2002 426ex
    white bros. r4 pipe, k&n filter w/outerwares and No lid, wiseco 11:1 426 , kibble white valves, stage 2 cam , 450r carb , +3 timing key , Lonestar +1 1/4 chromed swingarm, g-force +4 axle, Houser silcast +2 ST arms, 450r shocks with works zps triple rate springs , Hiper tech 3 beadlocks (with orange rings soon to be black), maier silver racecut plastic with a QT CF hood
    (work in progress)(NOW PARTING OUT)

    03 CRF450r
    (totaled and parting out)
    Now the new toy
    84 Chevy shortbed K10
    7in lift (4 suspension and 3 body)
    35in tires
    350 4spd
    (another work in progress)

  3. #3
    Join Date
    Sep 2009
    Location
    Bangor PA
    Posts
    26
    No I believe the rings are good.... it has plenty of compression and ran perfect before I took it apart..... it was heavy blue smoke before and it ranked of oil.... now its alnost pure white with no smell at all
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  4. #4
    Join Date
    Jul 2006
    Location
    Fairchance, Pa
    Posts
    1,207
    When is it smoking? all the time or mostly at start up? Did you soak the valve seals in oil for a while before assembling it? Did you check you ring gap before re-assembly? Did you check the cylinder for scaring before re-assembly? Just because you have good compression doesnt mean the rings and or cylinder isn't wore, you need to check the cylinder for scaring and ware and check the ring gap to know if the need replaced, if it is smoking constantly, more than likely you either need rings or have a wore out cylinder, my advice to you is to tare it back down and check the specs, a piston kit is around 100.00 and if the cylinder is ok run a ball hone through it and slap a new piston kit in it and you will be on your way.
    You said it is very hard to start, what did you set your valve lash at? the tighter the valve lash the harder it will be to start. Also make sure you have the timing right, one tooth either way will make it hard to start also. Hope this helps you out, give me a shout if I can help any further.

    Kevin Smitley
    Brandon Smitley #423
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