Exhaust Valve Question 2004 CRF100F with BBR 120 Kit
  • jrgcbg49
    Posts: 5
    Joined: Mon Oct 19, 2015 7:31 pm

    Exhaust Valve Question 2004 CRF100F with BBR 120 Kit

    by jrgcbg49 » Fri Apr 01, 2016 7:08 pm

    Reaching out to the experts again.2004 CRF 100 with BBR 120 kit. Compression 120psi hard to keep at idle and VERY hard to start.Picked up used. Put all new jets in carb. Decided to teardown to check "things". It appears whoever did the bbr kit was rough. Looks like they tried to change the valve springs without using the tool. (See pics of head.) Upon removing head found both valves leaking.(After spraying with carb cleaner to fill upside down with spark plug in). Cleaned up valves but seems the exhaust valve took a beating on its face? Again probably from the installer trying to change the valve springs without the tool! My question is can I still use this valve? A new one is about 45.00. Trying to keep costs down.I guess I will try to lap in and change the stem seals to see if it leaks? Will those marks weaken the valve and cause it to break apart? The piston seems ok.I think maybe the top ring was upside down. I have them soaking and will check for a number or letter to indicate top.It also appears the spring for the timing chain was not shortened either. With the assembly installed, the spring hook is about 1/4 inch above the hole it hooks on. Is there anything else I should check fix?
    Thank You.
    Photo's

    https://goo.gl/photos/5nNUJ4RhpuDcBiie7[/img]
    2004 CRF100F with BBR120 Kit
  • jrgcbg49
    Posts: 5
    Joined: Mon Oct 19, 2015 7:31 pm

    Solved my issue

    by jrgcbg49 » Thu Apr 21, 2016 1:57 pm

    Solved my issue with this bike Short version. I bought a new compression gauge.Re-tested and it was 110 cold and took several kicks to build to that.So I took the engine apart and found the intake and exhaust valves were leaking down.After cleaning and lapping they still wouldn't hold.Also checked rings and they were beyond spec.I replaced the piston and rings and intake and exhaust valves. Now the bike starts on second kick idles great and drives very well.
    2004 CRF100F with BBR120 Kit

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