CBR troubleshoot questions

Discussion in 'Road Warriors' started by two40two, Mar 25, 2013.

  1. two40two

    two40two ....

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    I'm in the process of making one good CBR from two not so good models. (1987 & 1989) A couple days of work later and suspension/swingarm/forks/brakes/cooling system etc has been put on the road worthy bike. Now it's time to make it run. After finding a leaky petcock I'm waiting on a part to arrive but I'm not ready to quit working on the bike.

    2 questions: can I bypass the fuel pump/tank on this and gravity feed it fuel?
    Will the kill switch stop the starter from turning the engine over? Turning it on or off had no effect on the starter cranking cranking the engine. None of my other bikes are like this- kill switch off-no cranking. I'm wondering if there might be an electrical issue to address there..

    I haven't confirmed it has spark yet. Next on the list. The starter turned the engine over no problem but I didn't hear any popping or sounds like it was about to return to life. Thanks!
    #1
  2. KungPaoDog

    KungPaoDog Been here awhile

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    If the bike is EFI (which I don't think those are) it will need the fuel pump. Carbs need far less pressure to function properly, and you can temporarily feed fuel from a squeeze bottle or something while trouble shooting. You could probably even run a carbed bike through half a tank or so before you need the fuel pump to get the rest of the gas out of the tank.

    I don't know about the kill switch functionality, but given the age you would probably be well advised to pull the whole kill switch circuit apart and give it a good cleaning. Shiny, non-corroded bikes rarely get re-combined into one good runner:evil
    #2
  3. two40two

    two40two ....

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    Carb, not efi. Thanks for the info.

    Looks like I'll be overhauling the switch assy for peace of mind.


    Sent from my stupidphone
    #3
  4. two40two

    two40two ....

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    So- spark plugs have a nice blue spark emitting.
    Replaced cracked fuel filter. Fuel pump clicks/thumps to the touch when start button is pressed.
    Removing fuel line to carb allowed a more than a few ounces to drain out from carburetor. Further leading me to believe the pump functions.
    Currently fueling is set up on a gravity feed to carburetor from squeeze bottle.
    I'm starting to wonder if 9 months of sitting has gummed up the carbs again with today's crap gasoline. Receipts say carb was cleaned out last summer.

    I have air, spark. Fuel is last on the list right?
    #4
  5. k-moe

    k-moe Long timer

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    Do you have good compression? It's a quick check, and pointless to go any further before making sure. If compression is good you'll be pulling the carbs for a cleaning.
    #5
  6. two40two

    two40two ....

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    Seems to have enough compression to continue. I disassembled/separated the carbs and have them soaking in pine-sol. I'll reassemble after a 3 day soak.

    Anybody have recommendations for tools and steps to take for carburetor set up? I have a yoshimura exhaust, (stage one according to p/o)needle and jet kit from the parts bike. What will I need to make these work after installation? Carb syncs needed and? The jets are a two-piece set up. Flat head screw threads into the jet body as opposed to the factory one piece jet removed by a slotted screwdriver. The aftermarket needles have a thin metal shim between needle and washer. I would like to use these if possible even though I have a factory exhaust and needle/jet set up. More power and noise is good in my book.
    #6
  7. KungPaoDog

    KungPaoDog Been here awhile

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    9 months can be plenty of time to gum up carbs under the right conditions. I've never used Pine-Sol to soak carbs, but I have used mono-filament (Thread or fishing line) to pass through small passages that didn't soak or spray clean. It isn't tough enough to damage soft metal parts. Just don't bust it off anywhere by forcing it.

    You'll need: vacuum gauges for a carb sync
    knowledge of how carbs work

    Carbs aren't that hard to make work well enough. Perfect tuning is a bit of black magic to a lot of us:lol3 It sounds like you know enough about carbs that you can pull off well enough, and probably pretty good.
    #7
  8. two40two

    two40two ....

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    #8
  9. chammyman

    chammyman Been here awhile

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    gravity feed is fine. my 1000 is gravity feed now.

    kill switch only stops it sparking. it will still crank.

    Are they 1000's or 600's you have?

    If the engines sound you can get it running with a dribble of fuel in the cylinders, won't run long right enough.

    Make sure the plug leads are going to the right cylinders if they have been off.
    #9
  10. two40two

    two40two ....

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    Thanks for the confirmation on the kill switch. They are both 600s.
    I'll have to double check the plug routing.
    I might swap the ignition module thingamajig whose name I cant recall right now that connects the spark plug wires to the rectifier. The plugs connected to the left side unit had a blue spark while the plugs connected to the right side unit had more of an orange spark. Who knows..

    The pinesol worked really well- i'll reassemble carbs by this weekend and find a vacuum gauge to sync them. Time will tell. I'm ready to get the old girl back on the road.
    #10
  11. duxrneet

    duxrneet Been here awhile

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    Mine is hard to start - give it as much juice as you can, it needs to spin pretty fast to fire. Might want to check valve clearance as well. They move around a bit when thrashed (mine does anyways :D )
    #11
  12. duxrneet

    duxrneet Been here awhile

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    ...and by juice, I mean voltage!
    #12
  13. two40two

    two40two ....

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    Juice it up! Got it. I was surprised at how quickly the battery drained after a few attempts at starting it. Thirsty electrical system.
    I guess I'll break down and do the valves while I'm at it. Hopefully that doesn't mean waiting for shims. Patience is not my strong point.
    #13
  14. duxrneet

    duxrneet Been here awhile

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    No shims necessary. Screw and 10mm locknut
    #14
  15. two40two

    two40two ....

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    Lots of tasks completed since the last post... I soaked the disassembled carbs and all non-rubber components in Pinesol with great success. After assembly and install- the bike ran! But the carbs were leaking gas from many diffferent points. Mucho dinero spent on o-rings later and my carbs do not leak. Swapping the 'spark unit' electrical piece was the missing link in getting the bike to fire up. I probably could have gotten away with not cleaning the carbs but I now have piece of mind after doing so that the carbys are spotlessly clean. And I got to try the Pinesol soak method. I'll never need carb cleaner for its intended purpose again. I also adjusted the valves to a consistent spec, leaning towards the tight side on intake and exhaust. After startup I let it idle for a minutes with a few throttle blips after warming up for the first time in 10+ years. All was well but after 2 start ups a sound started that seemed like a valve. I pulled the cover off once more and readjusted them again and it started up again with no problems or noises.

    which leads me to my next problem.... dammit
    After reassembling the carbs, dumping the fuel squeeze bottle for the proper fuel tank and charging the battery the bike started up with no hesitation after the last valve adjustment. It idled well for a minute or two while I messed with the choke and idle speed. Soon after the fuel pump started making a loud 'clacking' noise as it gyrated on its rubber mount. Soon after the engine died on its own accord sounding like it ran out of fuel.

    So- I pulled the fuel pump and lines from the good condition parts bike and swapped over the running cbr thinking this would take care of it. Now it doesn't start... I hate to buy a fuel pump when I have an aftermarket that looks very new on the bike now that I want to believe is good. The lines and hose clamps robbed from the parts bike look new, less than two years old if I had to guess.

    Possible causes I'm considering for no-start now:
    .5 gallon fuel isn't enough in the tank (although it started initially with half that amount in the tank initially.
    The fuel pump I took from the parts bike is bad or clogged with old gas..
    There is an electrical issue somewhere relating to the fuel system.. pump relay?
    I might have the intake/exit lines to pump swapped (I swapped them from what the manual said with no success already.
    Brand new fuel filter is already clogged... Highly unlikely

    I'm willing to bet if I was to hook up the squeeze bottle directly to the carb again it would start. I'm worn out from watching MotoGP all day @ COTA today and will have to wait to get the old girl running. Any input is greatly appreciated..
    #15
  16. manic mechanic

    manic mechanic Been here awhile

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    Since it sat for a time period, did you check out if it has a fuel filter that needs replacing. If I remember correctly, there was a filter between the pump and the carbs that sat cross-ways in the frame.
    #16
  17. hpsVFR

    hpsVFR Hoosier Daddy

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    Some thoughts off the top of my head (but it's late, and I'm not paying attention to the order in which I'd do any of this testing, so beware):

    It seems to me that the fuel pump itself is fairly easy to test: put the output hose into an empty can and hook the pump up to 12V. If gas comes out, you're probably fine. If gas doesn't come out, you've either got a bad pump or plugged hose (perhaps debris from the original pump?). If gas comes out, it's either a plug further down from wherever you disconnected the line, or an electrical issue.

    For the electric, first test should be to meter at the pump leads: do you get 12V?
    #17