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Valve Clearance, Carb Ballance & Head Job Advice Needed

Discussion in 'FZR250.com - Archives' started by hyperspeed, Feb 18, 2006.

  1. hyperspeed

    hyperspeed New Member

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    Hey all!

    I purchased 3LN3 a few months back. It's been going good and great fun until recently when it's slowly been going downhill. Performance dropped off, won't rev up all the way & hard to start when cold.

    I've checked the basics (carbs, plugs, leads, exup) and I've discovered compression is one cylinder is way down at around 50psi while the other 3 are up around 130. Put a bit of oil down the culprit cylinder and compression when up considerably so it's looking like it may need new rings or possibly just a valve clearance.

    The bike shops around here want to charge a fortune to do the job & claim parts would need to be ordered from Japan which could take months. So they recommend I just shell out a grand or so for another used engine. I'm not about to do that just yet & I've got most of the tools so I've decided to give it a go myself after reading some the excellent info in these forums.

    Before I get stuck into it I've got a few quick questions I hope you guys could help with.

    1) What should the valve clearance be? From previous posts I've found someone recommending Intake 0.1 - 0.2mm & Exhaust 0.2 - 0.3mm. But these was also another post claiming it should be Intake .10 to .15 and Exhaust .15 to .20
    Can someone who's done a valve clearance please confirm what works for you best?
    Will I need to pull the cams off to change the shims? any special tools/levers required?

    2) I'm probably going to need at least some rings & maybe pistons. Surely they must be available in Australia somewhere? Can anyone recommend where I may be able to source them from?

    3) A bit ahead of myself here but assuming I get everything back together again I'm going to need to do a carb balance. Now I've got a set of vacuum gauges but where the hell do I connect them to these Mikuni carbs?

    That's about it for now. Any help would be greatly appreciated.
     
    hyperspeed, Feb 18, 2006
    #1
  2. bombermanx

    bombermanx New Member

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    1.) according to the manual
    Intake: 0.11 - 0.20
    Exhaust: 0.21 - 0.30

    3.) look at the back of the carb near the drain holes, there are 4 caps that look like valve stem caps on a car's tires, held on by a little spring clip. Those are the holes for hooking up the gauges.
     
    bombermanx, Feb 18, 2006
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  3. TBone

    TBone New Member

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    I have to correct my friend on point 3... on the 3LN there are 4 screws in the body of the engine... just under the carbs... (looking from the back of the engine)
     
    TBone, Feb 18, 2006
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  4. ACE

    ACE Active Member

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    <!-- w --><a class="postlink" href="http://www.southerncrosssports.com">www.southerncrosssports.com</a><!-- w -->
    Thay have rings
     
    ACE, Feb 18, 2006
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  5. Ciaran

    Ciaran New Member

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    The 2kr and 3hx models have the valve stem cap type setup and like TBone said the 3lns have a screw in the rubber manifold between the carbs and the engine that needs to be removed. You will need adapters to screw into the holes if your gauges didn’t come with them.
     
    Ciaran, Feb 18, 2006
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  6. hyperspeed

    hyperspeed New Member

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    Thanks very much guys, a great help.

    Yup, I see the Allen key screws sticking out of the manifolds & have got adaptors to suit. Don't know why I didn't notice that sooner. I spent a good 10 minutes last night staring at the carbs trying to work it out, turns out I should have just looked a little lower.
     
    hyperspeed, Feb 18, 2006
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